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From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: John's Excellent battery adventure
Date: Tue, 26 Sep 2000 14:38:54 -0400

This was one of those weekends that started out from hell.  I went
to the MH to start loading it up Saturday night (our weekend is Sun,
Mon) and found that some prankster had unplugged the shore power
(left the plug hanging in the weather shield so it would look
plugged in.)  It had been unusually warm for this time of year and
I'd had the Maxxair fan on all week plus a light or two.  In other
words, my 300 amp-hour house battery was dead.  As in zero volts!
Gad!  I had a weekend of dry camping planned so I HAD to have
battery power.  With only 4 hours to departure.

OK, plug the rig in, check the E-meter.  No charge.  Damn, really
dead batteries.  Drag out the battery charger.  No charge.  Visions
of a midnight trip to Wally*world for something other than camping
dance before my eyes.  Then I recall a 15 volt, 250 amp power supply
I have, back from the days when men were men and computer supplies
were linear (for the non-electronic types, translate: about 250
lbs)  Roll that puppy out of storage on a hand cart, hook it up with
jumper cables, plug it in (one of the handiest things I've done was
to put a convenience outlet under the hood) and.... Nothing.  Bad,
very bad.  As the last ditch effort, I find a Variac in the shop and
bring it out.  Cranking that puppy up makes about 18 volts on the
power supply. Hope the 2 farads of filter caps hold. Hmm, a little
charging current.  Let's see where this leads.  Ten minutes later,
the current is 50 amps.  Another 10 minutes and it's at 100 amps.
Maybe there's hope yet.  Hook up a DVM to watch the battery voltage
and the current shunt. Regulate the power supply to 100 amps.  Check
the batteries every 10 minutes.  Hmm, no overheating - these things
might be OK.  Pack the RV in the meantime.  Three hours later, the
batteries start gassing.  'Bout right for that charge rate.

Unhook and away we go.  Batteries are still drawing current from the
alternator but that's to be expected because they need more than 300
amp-hours to bring them up completely.  By the time we reached the
camp site, the current draw from the alternator was nominal.  But
how did the batteries survive?  No way to know except to use 'em.
The good news is, we dry camped all weekend, pulled about 250
amp-hours from the batteries and all is well.

Moral of the story: Sometimes you really do need a bigger hammer.
Watch those hamfests, guys.  There are still a few of these boat
anchors floating around.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Flat Battery???
Date: Fri, 12 Jan 2001 01:19:17 -0500

Stan Birch wrote:

> Probably hasn't done your batteries any harm, and according to Ample
> Power, may have even improved them. This is what they recommend:
> Just as new batteries have to be cycled a few times before they
> provide optimum performance, old batteries can often be rejuvenated
> with one or two break-in cycles. Lost capacity and charge-acceptance
> can often be restored by a deep discharge followed by a slow
> charge.
> 1.  The first step to the process is a good charge, including a
> short period of overcharge. The overcharge will tend to equalize
> the specific gravity in all the cells.
> 2. Now that the battey is thoroughly charged, turn on enough loads
> to approximate a discharge of 5% of capacity. That is, for every
> 100 Amp-hours of capacity in your bank, discharge by 5 Amps.
> Assuming that your batteries have the expected Amp-hour capacity,
> the break-in discharge(s) will take about 20 hours. Let the
> discharge continue until the battery voltage reaches 10.5 Volts.
> 3. With a now depleted battery, recharge using a current of about
> 10-20% of Amp-hour capacity.

Discharge to 10.5 volts is nothing like discharging them flat and
holding them flat as happened here.

Discharging batteries flat and holding them for awhile will form
hard sulfate on the plates which is permanent damage.  It can be
partially recovered but the remaining life and some of the capacity
will be lost.

The process for recovering the batteries involves a hard
equalization charge for as long as necessary to bring the
electrolyte back up to the designated full charge specific gravity
in ALL cells.  In my case when some punks disconnected shore power
to my MH and the batteries sat flat for a week, this equalization
process took the better part of two days.  It requires a charger
capable of producing up to 18 volts at 50 amps or better.  With my
pair of Group 27s, it took 2 days at 40 amps (temperature limited)
with the voltage starting off at 17 and dropping to around 14.8 as
the sulfate is converted and dislodged.  This process requires
constant monitoring to avoid overheating and frequent addition of
water.  Typically one or two cells will be stubborn and resist
conversion until you're about to give up :-)  The electrolyte turns
dark from the dislodged active material.  This is because the hard
sulfate crystals are larger than the lead oxide or sponge lead that
it forms from and so pries little pieces of material off the
plates.  The material will settle after the process is finished and
the Trojans should have plenty of room below the plates so there
should be no problem with shorting.

My equalizing charger consists of a 250 amp unregulated power supply
capable of 18 volts fed from a Variac.  'Bout 100 lbs worth of pig
iron :-)

By my measurements I lost about 15% capacity from this incident.
This fits fairly well with battery mfr estimates that batteries will
withstand only "a few" complete discharges.

Frankly, I would not have done this process had I not had to
disassemble the front cowl to access these batteries.  If I had
known how much time it would take, I would have punted and traded
them in even with the labor of disassembling the cowl.

A more detailed account of equalization is contained in the Bureau
of Reclamation Battery Manual that I drop the URL for here every so
often.  I highly suggest you download it and read it.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Flat Battery???
Date: Fri, 12 Jan 2001 13:37:27 -0500

Stan Birch wrote:

> I don't think this will happen within a couple days or so though.

My batteries hard sulfated in a week of being fully discharged/held
flat.  Perhaps a little research on battery chemistry will alter
your "thinking".

> The furnace was left on for a week. and I'm not sure what kind of
> temperatures he is talking about; but assume that the batteries
> weren't left in a discharged state for more than two or three days.
> As long as they are immediately charged, I wouldn't expect that a
> great deal of harm has been done. If they were left a week in a
> totally discharged state, then I would expect some degree of
> irreversible sulfation.

> Not sure if it is necessary to put the boots to the batteries like
> this. A **long** slow charge at about 2 amps, like for about a week,
> can also be quite effective.

A long slow charge will NOT bring back hard sulfated batteries.
Both my experience and the literature say so.  If a long slow charge
brings the battery back, then it wasn't hard sulfated.  The pulse
charger camp claims to reverse hard sulfation but until I test one
in my lab, I take the claim with a grain of salt.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Flat Battery???
Date: Fri, 12 Jan 2001 15:49:44 -0500

ben hogland wrote:

> I will wait to place judgment I guess until I receive the RV back and read
> what the hydrometer readings are. As I said, I asked them to use a
> hydrometer and record the values and at that time, I'll either say yeah or
> nay. Nay meaning I want them to do something else to fix the problem.
> Do you both agree that if the hydrometer readings are good, the batteries
> are ok minus minor life span issues?
> I appreciate the feedback from both you and John..

If your hydrometer readings are OK, then the batteries should be
fine.  But if you hook a charger to them and they won't start
accepting current within a few minutes, just bet on having to do an
equilization.  In my latest case, I had two cells on each battery
(funny how that works) that were stubborn.  The other cells came up
fairly rapidly but it took the 2 day blast to get those two stubborn
ones up.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: portable generator power vs. solar power for 22' travel trailer
Date: Mon, 15 Jan 2001 23:24:21 -0500

Gary William Smith wrote:

> I would to hear from anyone who has knowledge of the plusses and minuses of
> using a 1000-1200 watt portable Honda generator to charge batteries while
> dry camping verses a 100 watt solar panel mounted permanently on the roof of
> the unit.

First question is, where do you live and do you have enough reliable
sun to make a solar panel worthwhile?  Around here you would have
been in the dark from about New Years until today when we got the
first sunlight of 2001!

Next issue will be when you'd be camping.  Even with clear skys most
of the year, you won't get much energy this time of year.

How do you plan on using 12 volt for?  A hundred watt/14 volt solar
panel is only worth about 7 amps so it will take many hours to
replenish significant use.  For example, my wife's 12 volt electric
blanket draws 8 amps starting and 4-6 amps running, depending on the
ambient temperature.  A 50 watt light draws 4 amps.  The gas furnace
will draw 6-10 amps, depending on model.  A Maxx-aire fan draws
about 8 amps wide open.  Very easy to out-strip your solar cells if
you have very much activity on your RV.

The portable generator is one option but matching it to a smart
charger to minimize run time requires some careful study.  If you're
not careful, you'll end up running the generator for hours with
little actual charging going on.  I was in the Atlanta West Marine
store today and looked over their selection of smart chargers.
There are quite a number available but they quickly get expensive.

I've just worked my way down this decision tree.  The two most
viable options for me involved either equipping my vehicle
alternator with a smart 3 stage charger or designing a purpose-built
charger. For a number of reasons unrelated to RVing, I chose the
latter.   For most RVers, the smart regulator is the way to go.
With a 150 amp alternator and a Cruising Equipment/Heart Interface
smart regulator, you can charge your almost dead house batteries (at
least to about 80%) in an hour of engine idling.  With our pattern
of use, that would have to happen every other day.

What I've done is design and build "Cordless Battery Charger II".
It consists of a small Honda engine, a 185 amp alternator and (for
now) a Heart Interface Incharge (same as Cruising Equipment Alpha
regulator.)  The assembly weighs about 40 lbs.  Cost is about $500.
It will charge my house batteries (to the onset of acceptance
charging or about 80%) in about an hour.  It is fairly quiet and
once the battery is charged about 40-50%, the engine can be
throttled way back for the remainder of the charge cycle.  I'm not
finished testing the Incharge in my lab yet but first impressions
are good.

The Incharge controller will eventually end up on my MH's alternator
after I complete the development of my own controller more closely
tuned to the application. I decided to punt and buy the Incharge so
I could start using the charger before my controller is finished :-)
I'll put some pix and description on my web site when I'm finished
with the project.

> Also would it be better in terms of how fast the batteries recharge to
> install two six volt batteries hooked up to deliver 12 volts (with another
> set of two six volt batteries in the bed of the towing vehicle to recharge
> with the generator) rather than the usual installation of two 12 volt
> batteries with a switch to access one or the other?

I run a pair of Group 27 12 volt batteries in parallel.  No need to
switch them.  They act electrically like one big battery.
Series'ing 2 6 volt batteries vs paralleling two 12's really doesn't
make much difference.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: portable generator power vs. solar power for 22' travel trailer
Date: Tue, 16 Jan 2001 22:57:27 -0500

Tom Fisher wrote:
> John, I note that Cruising Equipment recommends
> running the batteries between 50% and 85% state
> of charge with periodic equalizing. What do you think
> of this?

Trojan says that 80-90% discharge is OK for their batteries.  Since
the safe discharge level is completely dependent on plate
construction, one must consult the mfr for the specific battery type
involved.  I use the 80% mark for my Stowaways.  Seems to be working
fine so far.

> Also, other than monitoring the charge current,
> is there a charging voltage that would roughly correspond
> to an 85% state of charge?

Not really.  The 3 stage charger guys say that the end of bulk
charging is reached at about 14.2 to 15 volts, depending on
temperature and that this represents approx 80% of full charge.  I'm
finding that this is another one of those generalities that doesn't
really mean much.  AS IMPLEMENTED by Cruising Equipment, the
transition point is really the regulation voltage point.  When the
absorption LED comes on, the charge current doesn't immediately
drop.  The voltage is simply clamped at the transition point and
held there for the duration of the absorption cycle.  With the
Wally*World Group 27 battery I'm using as a test mule for
development, the transition to absorption does NOT represent 80%
charge.  I've terminated the charge immediately upon the absorption
LED coming on and then discharged it using my instrumented discharge
rig.  This particular battery is about 40% charged at the transition

The Peukert capable battery monitors are the only instruments that
get the state of charge even close.  I like my E-meter, though the
resolution isn't that hot.

For equalization, I use the Bureau of Reclamation battery
maintenance guidelines and find them to work well.  The Cruising
equipment 3 stage regulator I'm currently investigating has the
capability of doing mild equalizations.  If I had the regulator
mounted on a vehicle instead of on a portable generator, I'd be very
reluctant to use it for that because it will subject the whole
electrical system to up to around 16 volts.  I have a separate DC
power supply that I use for that purpose.

I find that with our camping every weekend and using the batteries
fairly heavily each weekend, an equalization is necessary every 4-6


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Converter/Invertor and/or ?
Date: Fri, 02 Feb 2001 15:13:21 -0500

Doug MacArthur wrote:

> - I'm confused about how the engine/alternator charges the house batteries -
> does the alternator go first into the converter or Heart charger? What about
> the lower charging current that's needed for the gel cells. I wonder how
> that is now being controlled.

ON the overwhelming majority of rigs, the house and cranking
batteries are simply paralleled across the constant-voltage
regulated alternator.  Whether the paralleling is done via a relay
or a diode, the result is the same - the batteries are presented
with a constant voltage and they each draw whatever current they
require for their state of charge.

> - would the 130 amp alternator be able to recharge the battery bank (say 50%
> depleted) in say 4 hours of driving, or will I need to add two 120 watt
> solar panels?  Note: I know all this depends on various important factors
> but I have to start somewhere :-)

The vehicle alternator will not charge the batteries in 4 hours with
the standard vehicle regulator.  The smart, multi-stage regulators
can but there are tradeoffs.  The only way to charge a battery
rapidly is to raise the terminal voltage and that is exactly what
the smart regulators do - as much as 15 volts or more depending on
the temperature.  One can charge a battery to about 80% in as little
as an hour at the expense of the high voltage.  Most gadgets can
handle the high voltage but light bulbs generally can't.  According
to an empirical formula developed by GE, a lamp's life varies as the
13th power of voltage!  The high end smart regulators have an input
to limit the voltage when lights are burning but that also limits
the charging rate.

If you want to fast charge your house batteries away from shore
power, you have to do it "offline" from the automotive side.  One
solution is a smart charger/converter/inverter running off the
generator while underway.  Another solution, one commonly used on
boats but strangely rare with RVs is a separate alternator for the
house batteries controlled by a smart regulator.  Yet another option
is something like my cordless battery charger that I've written
about previously, though I don't know of any sort of commercially
available unit that is affordable and portable.  If "affordable"
isn't a major issue, I can give you several URLs to companies that
make high current gasoline powered battery chargers.


From: John De Armond
Subject: Re: Battery charger recommendations?
Date: Wed, 21 Feb 2001 14:03:34 -0500 wrote:

> I took apart my Schumacher 6V/12V 2A/6A charger to find out what
> method of control they used and found to my suprise they use none! The
> voltage and current switches only selected different taps on the
> transformer, selecting a voltage, and neither voltage nor current was
> actually regulated. Hook it up to a dead battery and you'll see what I
> mean - the current pegs, even on the 2A setting.  I guess this is OK
> for occasional overnight charging but is far from optimal and not
> recommended for long term battery storage.

Actually it is controlled, you just can see it.  The control is via
leakage flux in the transformer.  This limits the current to some
designated value.  The voltage is controlled by the transformer
ratio.  This is effective since line voltage in most places is
pretty stable.  If you look at the core of your transformer closely
you'll find a tiny air gap somewhere, usually in the iron bar that
shunts the magnetic path from the primary to secondary.  Sometimes
the mfr runs a MIG bead over the gap so you have to look closely on
the inside surface to see it.

> The best chargers are the 3 stage automatic. They current limit
> initially until battery voltage rises, then switch to voltage control
> for tapered charging and finally switch to float mode. Float mode is
> the only way to go for long term storage. These units are pricey
> though and I don't know if you could find a dual 6/12 type.

That's a bit of a misunderstanding of how the "3 stage" (not really)
charger works.  In the charge mode, the charger appears externally
as a voltage regulated, current limited power source with the
voltage setpoint set to somewhere around 14.8 to 15 volts depending
on temperature.  The power source outputs its maximum current
(limited by electronics on line operated chargers and by the
saturation flux on alternator based units.)  until the battery
terminal voltage rises to the voltage setpoint.  At that point, the
power supply is voltage regulated and the battery draws whatever
current it can for an interval.  Most such chargers have an LED that
lights when the power supply starts regulating the voltage.  Many
mfrs say that the charger has switched from the bulk charge mode to
the absorption mode but it really hasn't.  The absorption period is
terminated by either expired time (poor, inexpensive) or by when the
charge current has dropped to typically 10% of that when the voltage
regulation started (best, more expensive).  At that point, the
voltage setpoint of the charger is reduced to something below 13.8,
the gassing voltage of ordinary lead-acid batteries (maintenance
free and gell cells a bit higher.)  This will maintain the charged
state of the battery.  Good multistage chargers will revert to the
higher voltage if any load is applied to the battery with the
charger attached.

My company is about to release an interesting new variation on the
multi-stage charger and I'm the design engineer so I've been
immersed in this for quite some time.  I've reverse engineered many
of our competitors' products and they all work as described above
regardless of whether the label says 2 or 3 or multi-stage charging.

Note that this exact charge regime can be accomplished on the cheap
with an ordinary battery charger or a DC welder, a stopwatch or
timer, a voltmeter and either a variac or an SCR motor speed
control.  One simply cranks the  voltage up to achieve the full
current capability of the charger (watch the temperature rise in the
transformer and rectifiers!)  When the appropriate battery terminal
voltage (a table of temps vs voltage is at is reached, simply turn the charger's
open circuit voltage down to that voltage and let the battery charge
in the absorption stage for either a couple of hours or until the
current is 10% of what it was when you turned the voltage down.
When the time expires or the current is down, simply turn the open
circuit voltage down to 13.8 and leave it there indefinitely.  I
have a homemade 250 amp charger that I operate just like that to
fast charge the batteries in my motorhome.  Never gotten around to
putting a smart controller on it.

To address another myth, it does NOT harm a battery to quick charge
it IFF the charge is controlled.  The only limit is the mechanical
integrity of the inter-cell connectors and plate webs and that is
very high.  The damage is done when the battery starts gassing while
under heavy charge.  The gassing literally blows the active material
off the plate grids.  One can actually see this happen in large
glass cased stationary batteries. A multi-stage charger will
terminate the high voltage charge phase before that can happen.  I
routinely charge batteries in under an hour and have done so for
years with great success.  One or two uncontrolled hard gassings
will kill a regular battery.  Even one will usually kill gelled and
AGM batteries.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Alternative to Generator/Solar
Date: Mon, 26 Feb 2001 15:26:44 -0500

John Elliott wrote:

> We like to go to remote places here in Oregon, no water or electricity.  We
> have a 26 foot trailer. On the second day the battery runs out and there is
> not space for another the trailer.  I would rather not hear a
> generator, and I don't want to spend the money on Solar.
> Last year I had the idea to put a battery or two in the back of the truck.
> Connect them into the trailer wiring, such that they charge from the trucks
> generator. This way they would get charged every time the truck moves, and
> by connecting the trailer to the truck, the trailer gets re-charged each
> time I come back to camp.
> Has anyone tried an arrangement like this?

Won't work very well. The problem is that the alternator's voltage
setpoint - chosen to make the vehicle battery last a long time -
isn't high enough to charge the house batteries at any reasonable

I've been logging data from my E-meter on the charging of my MH's
two Group 27 batteries.  With 100 amp-hours removed from the
batteries, it takes over 4 hours of road driving to charge them to
90%.  The first 50-60 amp-hours goes fairly fast with the alternator
delivering 60-70 amps (not bad for an 80 amp alternator!)  But once
the bulk charge phase is finished, the charge rate rapidly tapers
off.  And regardless of the driving time, the alternator never will
get that last 10 amp-hours or so in.  Simply takes more voltage than
is available.

IN contract, my Cordless Battery Charger (engine driven alternator
with multi-stage controller) will put 100 amp-hours in the batteries
in a little over an hour.   The difference is the multi-stage
controller's voltage setpoint is from 14.8 to 15.2, depending on

Before I built the CBC and installed the E-meter, I found that I
could go 2 days on my batteries on the initial charge.  Then I could
go a day on the amount of charge delivered to the batteries during
the normal tourist-type driving at the destination.  My solution now
is to run the CBC for about 45 mins to an hour a day, depending on
usage.  It costs me up to 20 amp-hours to recharge my electric
scooter so if I've used it a lot, it make take a little more time.

If you don't want to build a CBC or install a second alternator (the
other option), you can for much more money get a small generator
like the Honda EU-1000 and a smart multi-stage charger/converter and
achieve the same thing.  My CBC cost about $450 to build.  The honda
is near $700 discounted on the net and a high current multi-stage
charger/converter can run from $250 to $400.

Finally, you COULD buy sufficient battery capacity to let you get by
with just the energy contained in the bulk charge.  That way you
could partially charge them while you drive around.  That would be
at least twice the capacity that you have now.  You will need to
completely charge them when you return home or else they will
partially sulfate and lose capacity and have a short life.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: converter voltage out
Date: Wed, 09 May 2001 15:36:09 -0400

Dave Krajcar wrote:

> John:
> Thanks for the reply:
> Measured 16.7 at driver 12vdc lighter plug.  Measured almost same at battery
> terminals.  Converter does not have leds.  Cables to
> converter are very thick wire, #8?.   Have gotten Fleetwood involved and
> after some conflicting information, they agree that there is something
> wrong.  Batteries are 3 weeks old because old ones (1 year old) wouldn't
> hold a charge either.  Hopefully am getting new converter installed Friday
> if one can be located.

Good deal.  8 gauge wire is somewhat light if your charger does more
than about 30 amps and does not have remote sense.  Won't hurt your
batteries but it will slow the charge rate.

Here's some info for reference.

Check this document:

For a good explanation of multi-stage charging.  Look on page 4 of
the PDF for the charge voltage vs temperature table.  If your
converter does not have a battery temperature sensor, you'll need to
manually adjust your output voltage as the seasons change. Note that
these temperatures are listed for the actual battery temperature as
it is charging.  Charging at the 1C rate (the amper-hour rating
expressed in amps), I find that a group 27 battery will experience a
temperature rise of about 10 degrees F during the bulk charge
portion. You'll need either a glass or stainless stemmed thermometer
to measure the temperature of the electrolyte.  Based on my research
over the last 6 months, I have upped these voltages 0.25 volts.
That roughly corresponds to the start of the increase in temperature
that also signals the end of bulk charging.

Study this document to get a very concise description of battery
maintenance from a source that is completely commercially unbiased.

This is the Bureau of Reclamation's battery maintenance handbook.
We used almost identical procedures in TVA for battery maintenance.
The important of record-keeping can't be over-stressed.  Only with
organized records over time can you see a trend developing before
damage is caused.  For example, if you see the charged specific
gravity trending down on one or more cells, that means that you need
to check the charge process for inadequate charge and you need to
run an equalization.

I got interested again in batteries when we started dry camping a
lot.  I refuse to huddle around a candle in a dark RV to have enough
power for the trip.  I like my luxuries.  My motorhome is small and
I don't have room for larger batteries without structural
modifications.  I therefore had to develop procedures for getting
the maximum power from my batteries and for recharging them
quickly.  I bought an E-meter
(, mandatory IMHO for
proper battery use and I designed and built a Cordless Battery
- old photos but representative) so that I could quickly charge my
house batteries.  This unit will charge my pair of Group 27s in
about an hour and a half from 80% discharged to about 80-90%

My experience is interesting.  Shortly before I built the CBC I had
some punk unplug my motorhome which let the batteries discharge
completely.  zero volts.  I quickly built a line-operated charger
from a 250 amp, 12 volt power supply I had and started working on
them.  It took several hours to get the batteries to accept any
charge at all and over a day of equalizing to break down the
sulfation enough that the batteries would hold a half charge, that
is, about 100 amp-hours.  Through several full discharges (down to
10 volts) and fast multi-step recharges and through several extended
equalizations, I now have the capacity back up to 180 amp-hours.
The batteries were rated, optimistically IMHO, probably closer to
100-110, at 120 amp-hours each, I have been able to recover most of
my capacity.  My E-meter has all the options including a low voltage
alarm output.  I use this along with a contactor and some heavy
resistors to drain the battery fully and stop the discharge at 10.0

We use the RV every weekend and dry camp every 2nd to 3rd weekend.
I use around 80 amp-hours in a 24 hour period in the winter when the
heater and wifey's electric blanket is running.  In the summer, the
white neon I have mounted along 2 sides of my MH for campsite
lighting runs most of the night as we sit outside and read.  It is
12 volt powered so we use about the same power each 24 hours.  My
CBC will restore this in about an hour a day.  The time vs discharge
is non-linear because the absorption step can't be rushed much.  At
100 amp-hour discharge, the bulk charging is over in about 10-15
minutes.  The rest of the time is absorption where the charge rate
tampers from the 130 amp bulk rate to about 2 amps which is my
designated threshold for absorption termination.

Some interesting things to know.

Controlled fast charging, up to 2C but limited by cell interconnect
heating, does not harm a battery nor shorten its life.  "Controlled"
is the key word.  A properly tuned smart charger is a must.

Periodic equalization is absolutely necessary for long battery
life.  Each equalization knocks loose some active material but deep
discharge batteries are designed for this.  Think of it as being
similar to dressing a grinding wheel to expose new abrasive.

Overcharging (what an equalization really is) does not harm the
battery as long as the temperature is not allowed to rise much (my
standard is 20 deg F above ambient) and as long as the water supply
is maintained.

Specific gravity is a very poor indicator of battery state-of-charge
under dynamic conditions.  It takes hours for the electrolyte
between the plates to diffuse out to where the hydrometer can pick
it up - even on equalization.  SG is an excellent indicator of
battery state for a battery under stable conditions.  I find that
after about 3 hours, the SG reading in my particular batteries is
representative of the battery condition.  The way to see what your
battery does is to quick charge it and then take SG readings every
15 minutes or so and plot the data.  When the curve levels off, you
know at what point the SG reading is representative.

My concern is that my batteries preserve as much capacity as
possible during their useful lives.  This is quite distinct from
being concerned with getting the last month of life out of them.
Batteries are cheap compared to what they do so I don't mind
replacing them every 2-3 years.  My batteries are 2+ years old and
from the data I have recorded, it looks like that when they finally
reach the end of their lives, they will drop like rocks.  That will
happen when a good chunk of the active material is gone.  It will
NOT be because of sulfation.

This is an important thing to understand.  A lot of the advice
you'll get in this group and elsewhere on the net is taken from the
off-grid power people.  There, one IS concerned with how many years
the batteries last, as one can have thousands of dollars invested in
the battery bank.  Since the house doesn't move, it is easy to add
more batteries and limit the discharge to 50% or less.  Our
situation is different.  we don't want to haul around tons of
batteries and therefore we want the most performance from the
batteries we have, with calendar life being a secondary concern.

Hope this helps.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Magnetek 7345RU measured performance data
Message-ID: <>
Date: Sat, 08 Jun 2002 02:23:52 -0400

On Fri, 07 Jun 2002 22:39:53 -0400, GaryO <> wrote:

>All the recent discussion of the Magnetek 7345RU's charging
>capabilities over the past several weeks got me motivated to make some
>measurements on my unit.  Sorry for the long post, but the included
>data may prove interesting to some.
>I started with an older group 24, 12V "marine" battery that had not
>been charged or discharged in about a week.


>Note that the converter had only replaced 17.5 AH after 1 hour of
>charging, and it required 2.5 hours to deliver almost 30 AH.  I must
>say that I was rather disappointed.  I had hoped to be able to furnish
>at least 30A in 1 hour.
>Even more disappointing was the lack of any sort of two-stage charging
>capability, in spite of the advertising on the 7345RU's packing
>carton, which states "2 Step charging".

I think the problem is probably with the old battery and your voltage
setpoint.  Looking back through my engineer's log for the development of my
Cordless Battery Charger, I see quite different data for a new Group 27
battery.  We know that the internal impedance of a battery rises with age so
seeing an unexpectedly low charge rate with an old battery would be consistent
with this property.

With a fully discharged battery, my CBC will push 150 amps in for a few
minutes with the terminal voltage remaining below 13.5 volts.  At this charge
rate, the end of bulk charging is reached fairly rapidly, the voltage limit on
the regulator is hit (which defines the transition from bulk to absorption)
and the current drops over the next several hours.

I think what you're seeing is the charger in absorption mode from the
beginning because the old battery has a high impedance.  It should NOT
anywhere near that high a terminal voltage initially.  Compare your voltage
table with Fig 1 here:

He's charging Gell batteries which require slightly higher voltage but the
curve is representative. Note that the voltage remains relatively constant
after initially rising rapidly.

I've found the Trojan golf cart batteries to behave differently.  Mine have
practically no bulk charging.  The terminal voltage rises to the absorption
transition voltage within minutes of connecting my CBC.  The current then
tapers more slowly than either the Gells or a pair of Group 27s in parallel.
This somewhat thwarts my intention for the CBC of charging in around an hour.
With my previous pair of Group 27s, I could push over 80% of full charge in
about an hour to an hour and a half, depending on temperature.  My goal was to
run the CBC for an hour, plus or minus, each day when dry camping.  The Group
27s enabled that; the golf cart batteries don't.

Finally, a little clarification of "2-stage".  A 2-stage charger is nothing
more than a regulated DC power supply with current limit.  During the 1st
"stage" (bulk charge), the voltage is below the setpoint because the battery
is drawing current at the current limit setpoint.  The supply is effectively a
constant current supply.  When the voltage rises to the regulation point, the
supply transitions to constant voltage operation and the current gradually
decreases throughout the second (absorption) stage of charging.

If the charger had a third stage, then after either a period of time, or
better, when the current drops below a setpoint, the regulated voltage is
dropped to the float voltage which is normally set  just below the battery's
gassing voltage.

The Cruising Equipment regulator I initially used on my CBC had a simple,
settable timer that terminated the absorption stage after a set time by
dropping the voltage from the absorption voltage to the float voltage.

My own microprocessor-controlled regulator (and I think the Ample Power
regulator) terminates the absorption mode when the current drops to less than
(in my case) 5% of the max charging current.  This value isn't critical, since
the current finally drops fairly rapidly once the bulk of the absorption stage
is finished.

>Now I'm considering making some modifications to the converter in
>order to improve its performance.  Would anyone have a schematic for
>this converter?  Does anyone know if the "T" or timer option can be
>added onto it?  The naysayers will claim that this will void my
>warranty or cause danger to the RV or persons.  However, my warranty
>has already expired, and I feel quite competent in making these types
>of modifications should I find that the unit is capable of it.

Before modifying your unit, I recommend trying it with a known good battery
AND (if possible) setting the voltage limit higher.  Here's the table I coded
into my controller (from Cruising Equipment) to set my absorption voltage

120 	13.4 	12.5 		13.9 	13.3
110 	13.6 	12.7 		14.0 	13.4
100 	13.8 	12.9 		14.1 	13.5
90 	14.0 	13.1 		14.2 	13.6
80 	14.2 	13.3 		14.3 	13.7
70 	14.4 	13.5 		14.4 	13.8
60 	14.6 	13.7 		14.5 	13.9
50 	14.8 	13.9	 	14.6 	14.0
40 	15.0 	14.1 		14.7 	14.1
30 	15.2 	14.3 		14.8 	14.2

The temperature is the temperature internal to the battery.  I use the Gelled
battery table for my golf cart batteries.

You can see that at normal ambient you need much more than 13.8 volts to drive
the absorption stage.  When I had to set the voltage manually when using the
Cruising Equipment regulator, I simply stuck a small glass thermometer into
one cell.  I now have an epoxy-encapsulated thermistor sitting in an inner

Note that "absorption" and "acceptance" refer to the same mode. Ample power
and I use "absorption" because it is more descriptive of the process.
Cruising Equipment, Xantrex and a few others use "acceptance".  Same thing.

Finally, I wonder if the Magtek performs differently when plugged into shore
power vs the generator?  I have an earlier Honda inverter generator (EX-350)
whose inverter does NOT like the low pf load that a DC power supply or battery
charger presents.  It will drive battery chargers and DC power supplies but at
greatly reduced output.  If you could try your Magtek on both shore and
generator power and report back, I'd be very interested in the results.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Magnetek 7345RU measured performance data
Message-ID: <>
Date: Sat, 08 Jun 2002 14:48:10 -0400

On Sat, 08 Jun 2002 12:43:36 -0400, GaryO <> wrote:

>>If the charger had a third stage, then after either a period of time, or
>>better, when the current drops below a setpoint, the regulated voltage is
>>dropped to the float voltage which is normally set  just below the battery's
>>gassing voltage.
>Are you sure on this definition of 2-stage?  If true, then the
>original 6332 would qualify as a 2-stage.  My stand-alone battery
>charger, supplies 14.2V until the battery charge current drops below
>some set point, then switches to a 13.6V float setting.  This is what
>I expect a 2-stage charger to do.  I thought that a 3-stage charger
>included the higher "equalization" voltage.

Equalization is never considered another stage because it is never run
automatically, except on some large industrial battery bank management
systems. The reason is that equalization removes a bit of plate material each
time and so should not be run more often than necessary.  And it requires a
voltage high enough (about 17 volts in the case of 12 volts' worth of golf
cart batteries) that connected loads may be damaged.  I equalize my RV house
batteries about every 2-3 months and my car batteries (also deep discharge but
of conventional design) every 6 months or so.  I use a special equalization
charger that I built and I disconnect all loads before equalizing.

Yes, I am sure of the definitions.  Read either Cruising Equipment ne Xantrex
or Ample Power's web site, Home Power magazine's technical documents area,
that BoR document on battery maintenance that I post a URL to periodically.

To a degree, the stage definitions are a bit hyped.  A conventional cheapo car
battery charger is a two stage charger because the leakage flux transformer
limits current and the turns ratio sets the voltage.  It charges constant
current until the design voltage is reached, then it charges constant voltage.
And even a cheap charger like the "automatic" one I bought at WallyWorld a few
months ago does the 3rd stage, in that it cuts back to the maintenance voltage
when the absorption stage is completed as measured by voltage in this

The people who make the very expensive chargers and regulators want to you to
believe otherwise but once you have one of their products in your lab and test
it, you find otherwise.  I've tested and reverse engineered both the Cruising
Equipment and the Ample Power charge regulator and have tested a Heart
inverter/charger (owner wouldn't let me take it apart :-)

I can accept the claims they'd make that active voltage and current regulation
along with a positive means of terminating the absorption stage is better than
relying on a leakage flux transformer and mains regulation.  But the expensive
units ARE fundamentally the same as the cheaper ones.  Is it worth the extra
money?  In my case, yes, since positive regulations also makes adjustment

Then there's another type of charger that doesn't fit into any of these
categories but it charges just as rapidly and maintains the battery just as
well as the others.  I call it a toggle charger.  I've seen some folks call it
a pulse charger but this term is mis-applied.

This charger operates conventionally in the bulk and absorption stages,
current regulated and then voltage regulated.  The difference is in the
maintenance/trickle stage. When the voltage rises enough to signal the end of
the absorption stage, the current is turned off completely.  There the system
sits until the battery voltage falls to a setpoint.  The full absorption
voltage is again applied and the cycle repeats indefinitely.

This is a popular design for EVs.  Exide makes a well known one in several
different sizes.  I have about half a dozen of their 24 volt models for my
various LEVs.  A good, high quality battery like a Hawker will, when charged,
sit there quiescent for 45 seconds and then accept charge for perhaps 2
seconds.  Lesser batteries have shorter quiescent times and longer charge
intervals.  One LEV that still contains the original cheap-sh*t chinese gells
toggles back and forth every 10 seconds or so in almost a square wave.

>Good point.  I was running the Honda EU1000i on its eco-throttle
>setting, and it was just loafing along.  Perhaps I should have tried
>turning this off so that it would run at its maximum.  Unfortunately,
>my trailer is in a storage lot with no available electric, and
>bringing it home is not a possibility.  This particular experiment may
>have to wait until I'm in a site with hookups.

I don't think the eco mode will have any effect but who knows?  On mine, the
voltage and frequency are set entirely within the inverter and the engine only
runs fast enough to supply the demand.  I assume from reading the literature
that the new hondas work the same way.  My concern is that the inverter might
not like a highly capacitive or rectifier load.  The rectifier load in
particular drives mine bat-shit.  It turns on for a half-cycle, turns off
again and then back on before the half-cycle is finished.  This makes the
transformer in the charger hum at a high harmonic and reduces the output.
Probably the large inrush when the rectifiers conduct is fooling the current
limit circuit in the inverter and causing it to momentarily shut down.

>Thanks John for the suggestions and insight.

Yer welcome.  Glad to share.  Battery charging technology has fascinated me
for 30+ years, ever since I got handed the responsibility for the 500k
amp-hour, 250 volt vital bus inverter batteries at my first nuclear plant.
Maintaining a large battery like that to nuclear standards is very time
consuming (daily surveillance, including random cell SG and calcium potential
sampling) and the charging equipment is very sophisticated.  Despite the
patents thrown out willy-nilly in the last 10 years on multi-stage charging,
MS charging has been around at least since the 60s.

Of course, the 19" rack full of instruments driven by a PDP/11 minicomputer
that we had back then has been condensed into my little dash mounted E-meter.
And I get more info from the E-meter than I did from the instrument rack.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Vector Charger characteristics
Date: Tue, 06 Apr 2004 23:50:58 -0400
Message-ID: <>

On 6 Apr 2004 11:02:09 -0700, (dave martin) wrote:

>I just received a Vector VEC1093 2/10/40/100 battery charger from
> for $110 incl. shipping.
>I'm interested in its utility for rapidly charging batteries so I took
>it to an Auto Electric shop and they measured its Volt/Current output
>in "bulk charging mode". The data are:
>12.3 volts 43.0 amps
>14.3 volts 40.0 amps
>14.5 volts 22.0 amps
>14.8 volts 00.0 amps
>Just what a bulk charge phase is supposed to do.

Yep.  Mine came today too.  Here's the "5 minute impression".

I hooked the thing up to a pair of Stowaway 6 volt golf cart batteries that I
had removed from service and allowed to sit around for at least a year.  The
open circuit voltage was 10 volts even.  I punched up the 40 amp mode and
watched the charger immediately ramp up to 40.5 amps, accompanied by a fairly
loud fan.

I hooked a logging voltmeter up to the batteries and went to do other things.
A brief examination shows that the terminal voltage rose gradually to 14.8
volts and held there.  The charge current then tapered from 40 amps down to
about 5 amps, whereupon the charger converted to the lower trickle charge
voltage.  Some time after that the charger displayed "FULL" on the display and
turned off, allowing the terminal voltage to gradually coast back down.

This is the classical three stage charge cycle.  In short, Vector just blew a
LOT of much more expensive chargers out of the saddle.

When  I went back to the shop I decided to see if the charger would
automatically go back to the bulk mode when a load is applied or if it
required manual intervention.  Unfortunately in getting ready to apply a load
I knocked the charger clips off and when I reattached, it started another
charge cycle.  I'll have to let it complete and do this test tomorrow.  I have
an unfortunate feeling that the absorption phase is based on time instead of
current decay which will make this thing a lot less flexible.

It is already evident that this unit cannot directly substitute for a
converter/charger.  The reason is that the charge cycle must be  manually
initiated each time.  that would preclude mounting the unit out of sight.  It
would be a pain to have to remember to punch the unit on every time shore
power is restored or the generator cranked.

It should be very good, however, for one-shot charging while dry camping.  The
way I use my cordless battery charger.  Plug it into a small generator, punch
it on and let it charge away.  I'm going to test it tomorrow on a variety of
small generators to see how it works.  Sometimes inverter generators don't
like the highly capacitive load the charger presents.

One thing very interesting that I've already noted is how much capacity this
charger has already recovered.  When I returned this evening, both batteries
were overflowing electrolyte.  The levels were correct, about half way between
the plates and the filler, when I started.  What is happening is that the
charger is converting lead sulfate back to lead oxide and lead sponge and
releasing acid.  The released acid filled the cells to overflowing.  The
normal single stage charger and even an occasional application of the cordless
battery charger had not been able to convert this sulfate which represents
lost capacity.  I bet a bunch more will come out when I trigger the
desulfator.  I haven't scoped it yet but from the slight singing I could hear
when I briefly activated this mode, it should be a powerful one.

I'll do more extensive testing and perhaps post some photos in the coming
days.  Meanwhile it has become painfully evident that I'm going to have to buy
a second unit for my shop.  This one is going in the RV.  It's a keeper.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Vector smart charger testing
Date: Mon, 12 Apr 2004 17:29:05 -0400
Message-ID: <>

Executive Summary:  This is one damned fine charger, probably the best I've
had an opportunity to test.  Only fault is the LOUD cooling fan.


I've completed the first part of my testing, a complete charge/discharge cycle
on the StowAway golf cart batteries.  Photos and data are here:

Of particular interest is this:

This is the scan of the strip chart from a recording ammeter.  The sideways
numbers indicate hours.  The scale is 0-10 amps.  This ammeter recorded the
120 volt line INPUT amps to the charger.  It illustrates some interesting
data.  The Vector unit is doing an exquisite 3 stage charge cycle.

The bulk stage is the first part of the graph.  It is a constant current, 40
amp charge.  One can see the input current rise gradually over the course of
the charge.  This corresponds to the rising battery terminal voltage at the
constant 40 amp current.

When the battery voltage reaches the 14.8 volt setpoint, the bulk stage is
finished and the absorption stage commences.  The charger reduced its voltage
to 14.02 for this stage.  This is different from most chargers but of no

The absorption stage lasted for about an hour and a half.  The end is
indicated by the sharp drop in current on the chart.  Float ran for about 2
hours, whereupon the charger turned off and displayed "FUL" in the display.

The total charge cycle took about 7 hours.  Most of the charge had been
returned to the battery at the end of the bulk stage, 4 hours in.  This is
most impressive.

During the bulk stage, the charger delivered (4hrs*40amps) 160 amp-hours.
That compares quite nicely with the 157.8 amp-hours recovered from the battery
during the first discharge test.  One way to look at it is, the bulk stage put
back the energy used and the other stages accounted for the inefficiency in

As of this moment, the second discharge test is running.  When I checked it
there were 764 minutes on the clock (about half way discharged) and the
terminal voltage had already dropped to 11.86.  This illustrates the
relatively high internal impedance of this type of battery.

Below is a copy of my test log containing the actual data.


Vector Smart Charger Test Log

Initial test
04/08/04  Thurs

I hooked the Vector to a set of StowAway golf cart batteries that I had
sitting around the shop.  They had been removed from my RV >1 year ago and
were being saved for the core value.

The charger immediately ramped up to 40 amps and held it.  I left the charger
to complete the cycle in preparation for a discharge test.

04/09/04  Fri

I observed that the Vector completed its charge cycle and shut off, indicating
"FUL" on the display.

I connected my discharge tester to the battery and set the discharge current
to 5 amps.  The discharge took 1875 minutes, 31.25 hours.  That computes to
157 amp-hours.  Stop voltage was set to 10.5 volts.

04/10/04 Sat.

New charge started at 5:10 pm.  Battery terminal voltage before commencing
charging is 11.15.  Immediately after turning on the vector and setting it to
40 amps, the battery terminal voltage rose to 12.15.  Recording ammeter
connected to the 120vac input showed 5.4 amps.

Checked the actual charging current with the Tong Tester DC clamp-on ammeter.
It indicated 42 amps.  The Vector display indicated 40.7.

Approx 9:15 pm.  Bulk stage is finished.  Battery terminal voltage is
14.80.  Current remains at 40 amps.  Input current had risen to 6 amps
as the battery terminal voltage rose.  Absorption stage started with a
terminal voltage of 14.02.

Approx 10:30.  Absorption stage is complete.  Terminal voltage for the start
of the float stage is 13.85.

Approx 12:30 amp 04/11/04

Float stage finished and charger turned off.  At this point I pressed the
"desulfate" button and left the unit to run.

04/12/04  04:00 am

I found the charger off, the desulfate run apparently controlled by a timer
which had expired.

Second discharge test started.  Current again set at 5 amps.

04/12/04 4:50 pm.  Checked the progress of the discharge.  746 minutes on the
clock.  Terminal voltage is 11.86.  Load is still 5 amps.

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Vector smart charger testing
Date: Thu, 15 Apr 2004 02:15:01 -0400
Message-ID: <>

On Wed, 14 Apr 2004 19:18:28 -0700, "Ben Hogland" <>

>Good work, John, and interesting info..
>One thing that I notice is your float voltage differs from my vec1093 float
>voltage. Mine is a steady 14.15 volts. I also noticed that yours has a top
>bulk charging voltage of 14.80 volts where mine topped out at 14.89 volts..
>This is probably due to calibration differences; doubtfully meter accuracy
>differences as the specs for yours and my Fluke are much tighter than that.
>These differences are minimal but interesting to me in that I'd expect
>tighter tolerances from a charger such as this..

I can write off 90 mv to tolerance buildup.  Maybe a little difference in
calibration on our meters too.  I know mine 88 is still spot-on because I have
a Fluke bench DVM calibrator to check it against.  Nothing I can do if it ever
gets off because this meter is soft calibrated through the beeper.

>Another observation I made this weekend when I operated my Vector powered by
>my Onan 4K Micro-Quiet is that the current fluctuates by 10 amps erratically
>after the battery will no longer accept full current capacity..  That is,
>the charge current starts off at 40 (plus) amps pegged then after a time
>starts to go down; during the time when the current is between 30 and 40
>amps the current fluctuates erratically until it drops below 30 amps (at
>which time the Vector amp reading stabilizes). This is the reading from the
>Vector amp meter and I have no idea yet if it is honestly fluctuating to the
>degree it appears to be since I did not have a current meter of that
>capacity handy. I did read the voltage during the erratic current
>fluctuation and it seems to be steady so it may very well be just an anomaly
>of it's current meter. I haven't confirmed it yet, but I suspect it's
>related to running the Vector from my generator..

I just got my repaired generator installed a couple of hours ago so I haven't
had time for much testing.  My house batteries were pretty well charged.  I
drained off a few ah by heating water in the microwave for awhile.  I din't
notice the current fluctuation but I did notice that it does NOT like going
immediately to 40 amps.  I'd hear it load the genny for an instant and then
the display would pop up FUL.  If I let it go for 10 seconds or so on 20 amps
and then push the button one more time it hit 40 and stayed there.  I'm doing
a 4 day dry camp this weekend so I'll give it a working over and see what

>Something that was interesting to me is that the Vector is indeed *smart*.
>It checks the state of charge and if the battery only needs a top-off
>charge, it won't deliver the higher voltage but delivers the float charge
>immediately. It appears it does this by starting off the charge and if it
>senses the voltage raises to a set level, within seconds of the charge
>start-up it pauses for up to 5 minutes apparently waiting to see how low the
>battery voltage drops. If it determines that the charge state is beyond a
>set level, it will only deliver a float voltage level of 14.15 volts until
>the battery is topped-off..

Noticed the same thing.  It also stops every few minutes to measure the
battery state during oh, probably the first 20 minutes of charge.  I haven't
stopwatched it but that seems about the interval.  It may check later too, I
haven't been around during a whole charge cycle.

>One thing is for sure, this Vector charged my coach batteries far faster
>than the converter would have. It was very nice having the ability to fully
>charge my two coach batteries quickly from the gen while I was out RVing
>off-grid this week.
>Have you tried the Vector using your generators/inverters yet?  I'd be
>interested if you find that there are some anomalies due to using a gen or
>an inverter.

Just for giggles I did hook the Vector to my 1 kw inverter to see if it would
run.  Perpetual motion, anyone? :-)  It did in fact run.  This is a
pseudo-sine jobbie. I did hear some 60 hz "ticking" coming from the unit but
it had no problem running and delivering full output.

Speaking of inverters, I lost my second Vector 1kw to load dump tonight.  I'm
getting a noid.  I have a somewhat flakey transmission interlock switch and
sometimes I have to jiggle the gear shift a bit while holding in START to get
the starter to fire.  Usually it just jogs the starter a time or two before it
catches.  One of the jogs smoked the inverter.  This is really crappy.  It's
not like load dump isn't a well-known phenomena in vehicles.  Fortunately I
have a good warranty on it.

I installed that $79 Xantrex 1kw inverter from CostCo.  Much smaller than the
Vector but actually performs better.  The output is at least somewhat
regulated.  The Vector isn't.  When the battery voltage sags with the Vector,
so does the output.  I think my microwave ran at full power for the first time
since I wired it to the inverter.

Alas, nothing is perfect.  The cotton pickin' thing trips on overvoltage on
both the Vector charger and the alternator output when the engine first starts
and the alternator is still cold.  The Vector would ride right through that.
I didn't see any adjustment pots on the PCB so I'll probably have to figure
out which fixed resistors to change out to raise the trip a bit.  That throws
a big kink in my electric fridge/inverter combo.  Darn!

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Vector smart charger testing
Date: Fri, 16 Apr 2004 02:55:54 -0400
Message-ID: <>

On Thu, 15 Apr 2004 12:12:21 -0700, "Ben Hogland" <>

>The float difference is 130 mv off. My 79 III is annually cal'ed. I have two
>other meters so next time I'll also check it with one or both of my other
>meters. Even my Megnetek is dead-nuts on 13.8 volts (float) as it says it
>should be.. I agree that it's likely tolerance stack-up. That kind of
>stack-up to me sounded unusual although I agree that it's not really

It is curious, though.  My Fluke calibrator is traceably calibrated every
couple of years (I have a 15 year history of stability to fall back on for
that interval.  Antique instruments do have their places :-) It would be
interesting to test some other Vectors with traceable meters to see how close
they track.  I'm almost surely going to get another one for the shop (this one
is going in the RV) so that'll be a second checkpoint.

>Yeah, the current fluctuation has me a little concerned and I need to verify
>whether is was the gen or not causing it. I'd be interested to know if
>anyone else has seen this anomaly or maybe it's just my unit. I guess it has
>me concerned because anomalies like this *could* be a sign of impending

This Generac Impact 36 inverter generator produces cleaner power than TVA
during the day.  At night when all the inverter motors are turned off at the
Maytag factory across the street, TVA about ties it at about 1% THD.  I'm not
sure mine is a very good test.  I have, however run the inverter on my Yamada
generic chicom 1kw 2 stroke generator with success.  I have no idea of the
power quality from this thing, though judging by the weight it should be good.
I'll measure it sometime.  It was interesting that the Vector was similarly
reluctant to start at 40 amps.  I wrote it off to the little generator not
having enough flywheel reserve.  Maybe I'll look at that again.

>You really do run your batteries hard, it sounds.

Yeah, some of the time.  The 'fridge is on the inverter all the time.  About
90 watts.  The microwave makes the inverter draw about 80 amps so it's pretty
close to the inverter's capacity.  I have the microwave wired in permanently
along with the 'fridge because making a transfer switch that wouldn't smoke
the inverter was getting complicated.  I learned via the blue smoke route that
if I just relay switch from shore to inverter power, the coasting refrigerator
compressor acts like an induction generator and feeds back enough power to
smoke the inverter output stages.  It was looking like two separate relays
with a time delay between them.  Not worth it.

Then there's the lighting.  I've upgraded each fixture to 12 volt 30 watt dual
tube units.  I didn't give much thought to them all being on 1 12 volt branch,
the same branch my CO detector is on.  With 'em all on, they apparently draw
more than 20 amps because the auto-reset breaker on that branch trips.  Then
the CO alarm goes ape-sh*t from loss of power.  Not a pretty sight.  Anyway,
that's a pretty good draw on the batteries too.  I don't particularly like
having that much light but my eyes aren't cooperating much anymore.

>I have one 500 watt
>inverter which I really don't use much because I find it useless for most
>things other than the TV. I replaced my AC only TV with a AC/DC TV thus now
>I don't even need the inverter for that. Most of my battery consumption
>comes from the use of my furnace blower and lights. The temperatures were
>down in the 20s at night on the trip I just returned from thus the furnace
>was working hard. The LED lighting I have worked great on this trip thus
>lighting wasn't really a factor. If I need a lot of power, I use the
>generator. Of course, that can be a problem if it's during quiet hours at a

My l'il hydroflame furnace only draws about 4 amps now that I've overhauled
the motor.  I think that's better than new.  I just hate to crank the genny to
nuke a TV dinner or make a pot of coffee.  I like to let it fully warm
whenever I crank it which, as we learned last summer, takes about an hour :-)

>Thanks for the great tech write-ups, John, I enjoy reading your reports. Let
>us know how the Vector works on the gen during your 4 day trip.

Glad to hear that.  I have a report on my new Generac Quiet Pack 55g (I'm up
to 9 generators now.  I really need to thin the flock...) to write up.  I'm
most impressed.  Quietest 5kw generator I've ever had in my shop.  I'll report
back on the Vector next week.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Trailer battery life ?
Date: Tue, 25 May 2004 01:16:00 -0400
Message-ID: <>

On 23 May 2004 14:35:20 -0700, (Pete Dumbleton)

>Neon John <> wrote in message
>> I highly suggest getting a generator, even if it's a little 1000 watt portable
>> unit.  It and a smart charger like the Vector make dry camping a LOT less
>> stressful.  You can use power as you like and not have to worry about running
>> out.
>John, I stopped in a WallyMart that carried the new Schumacher line
>and read the manual for the mid-range charger like my Vector (same
>amps -- same price).  The Schmacher is a tad heavier, but seems to do
>everything the Vector will do and then some.

I bought the "40 amp" Schumacher a couple of weeks ago to test.  I've run it
through my lab to satisfy my curiosity but I won't be posting a review since I
might be accused of belittling someone.

>As I have remarked elsewhere, when my Vector is done charging, it
>switches itself off and must be manually switched on to charge again
>if you have used the battery (altho I discovered that if I am using
>the battery while it is still charging, the Vector will stay on until
>the load, even a light one like my 8W florescent reading light, is
>switched off).  The Schumacher instructions indicate that it has a
>maintenance mode after the float mode that will allow it to switch in
>and out of float as needed.

I have not tested the maintenance mode yet.  I can say that this charger is
quite different than the Vector, superior in some ways, inferior in others.
It apparently has a very powerful desulfator function, as I can hear the
battery plates singing when it is operating.  There is no separate mode for
desulfating - it selects when to do it.  The major downer is that the labeling
is fraudulent.  The "40 amp" charger isn't.  In the fine print on the back of
the charger itself it lists the 40 amp output only for a relatively low duty
cycle.  Twenty amps is as high as I saw it go, and that includes being applied
to a fully discharged pack.  I haven't been able to test the desulfator
function, as the Vector has nicely desulfated all the old batteries I had
laying around :-)

I was really hoping this would be as good a charger as the Vector, for the
packing is much nicer.  I also like the connections, standard male plug for
the power and an Anderson clone for the output wires.

I notice with the Vector that as long as the charge cycle has not completed
(FIN on the display), the unit will return to full bulk mode with a load
applied.  Only after FIN appears is the charger stuck in trickle mode.

The Schumacher  has one majorly annoying "feature".  There is no power switch.
When an error mode is entered or the cycle completes, the unit must be powered
down by unplugging the cord to reset.  Even though the male plug is right
there on the cabinet, it is a major pain to have to pull the plug off and put
it back on every time.  I don't think a simple on-off switch is too much to

Both of these chargers require manual button pushing upon powering up so
neither can be used as automatic chargers.  If I'm going to have to have the
charger out in the open and remember to push the buttons, I'd rather have the
Vector, both for the higher output current and the on-off switch.

The trickle mode might do the job most of the time.  My converter only charges
about 5 amps when no other charger is connected and that has maintained my
batteries for years under ordinary use (NOT dry camping).  The trickle charge
mode is about 3 amps.  If lights and maybe a fan were the load then the
trickle mode would probably make up the battery overnight.  If not, a few
button pushes would start the high current charge.

There is one other problem.  I have an Xantrex inverter wired in permanently
to run the 'fridge and microwave.  Its high voltage trip is set quite low, low
enough that it trips on the float voltage from the Vector.  That means I have
to check the inverter every time I charge the batteries.  The Vector inverter
I had before it didn't have this problem but it couldn't withstand load dumps
and I got tired of sending it back on warranty.  I can poke around in the
Xantrex and change the high voltage setpoint but that's not a general solution
for everyone.

BTW, that big pod on the bottom of the Vector below the aluminum extrusion is
an add-on just to hold a line filter.  If you don't have serious concerns
about EMI, you can remove that pod and have a very compact little charger.  I
just got in some nice self-contained miniature EMI filters that I can mount
inside the main case.  The pod will be history, along with that miserably
stiff power cord.  I've already replaced the power cord with a 20 ft, 16ga
cord.  Very nice.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Schumacher smart charger update.
Date: Sat, 14 Aug 2004 20:46:47 -0400
Message-ID: <>

The Schumacher smart charger is dead.  The blue smoke leaked out.

Today I bought 8 6 volt golf cart batteries to go in my electric car.  I was
giving them all a good equalizing charge before installation.  I was using
both the Schumacher and the Vector on a small generator, charging 4 on each
charger.  the generator ran out of gas and quit.  When I brought it back up
and plugged in the Schumacher, it presented a dead short to the generator.  No
problem with the Vector.

Fortunately it's still under warranty so it didn't cost me anything.  I am
surprised that it was so succeedable to (I'm guessing) off-frequency power.
That good ole Vector just hammered right on through.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Ever Hopeful, Bob Buys a Hammock
Date: Tue, 21 Sep 2004 22:18:19 -0400
Message-ID: <>

On Tue, 21 Sep 2004 13:01:45 -0600, Bob Giddings <> wrote:

>Every thing I read away from you says that this sort of fast charging
>will shortly kill the batteries.

Not from me.  My experience is that, except for cranking and standby
batteries, fast charging has no effect on the overall life IFF the charge is
properly controlled.  I think that the bad rap quick charging has gotten is
rooted in the infamous wheeled garage charger that all mechanics seem to have.
They'll output 100 amps or more at an unregulated and uncontrolled voltage.
I've seen the open terminal voltage as high as 20 volts!  Hook that sucka up
to a car battery, crank in the fast charge setting, come back in a few hours
and find a thoroughly fried battery.

>In any case, golf cart batteries
>seem to be the last sort to take it well.  I seem to recall that even
>you had problems getting them to take it.

yep.  The high internal impedance does make fast charging difficult IF the
battery is hooked to the system and thus subject to voltage constraints.  GC
batteries CAN be fast-charged if there is no limit on the voltage and the
temperature is monitored.  That old charger in my CitiCar that I mentioned is
an example.  The open circuit voltage out of that thing is around 70 volts for
a 48 volt pack!  One was supposed to estimate how much juice had been used on
the trip and set the built-in timer accordingly.

One of the EV listers had a T-105 explode awhile back.  He was drawing several
hundred amps from the battery set when an internal connector melted, arced and
set off the explosive gas mix above the plates.  It blew the lid off as
cleanly as if it had been cut.  He posted some photos and we all marveled at
how small the cell interconnects were.  No wonder the batteries have such high
internal impedance.  That probably isn't much of an issue for RVers unless one
installs one of those 4kw inverters and tries to run the AC on it!

>You are right about the 90 A.  I was reading the choices off an old
>sheet I got with the 30 A.  I am reluctant to be blase about the
>heating problem.  I may go with 40 or 45.  I have to do a little
>research and find out what the resistance really is over the 15 or 20
>foot of AWG 8 over with the various amperages.  And how that converts
>to heat.

Here ya go.

8 ga wire has .000739 ohms per foot.  Let's say you had 15 feet of wire.
15*0.000739= 0.011085 ohms total.  power dissipated is "I squared R".  For 40
amps that would be 40^2*.011085= 17.736 watts over the entire length or 1.182
watts per foot.

Converting power dissipated to temperature rise is somewhat complicated.  For
a free-air radiator (a wire in the open), Stefan's law is a good approximation
that doesn't take into account convection.

Stefan's law says that power radiated goes up as the 4th power of temperature.

P=SAT^4 where
	S is stefan's constant,  5.67 x 10-8 W m-2 K-4
	A is Surface area (square meters)
	T is absolute temperature in degrees Kelvin

The important thing to understand from all this greek is that a small increase
in temperature results in a huge increase in radiated power.  Conversely, a
significant increase in power results in only a tiny increase in temperature.
In other words, push more power through the wire and the temperature rises
only slightly.

This holds only for wire in free space.  If the wire is under carpet, embedded
in insulation or otherwise restricted, then the situation gets complex.
Really good insulation, say, UF or urethane foam, could make the wire overheat
even below its nominal current rating.

So.  Before I increased the load on a wire I'd want to know its path to make
sure it isn't buried in insulation or something.  What I'd do is follow the
wire from converter to battery.  If I could not visually follow it, I'd
replace it so that I'd be sure of its routing.

Before replacing the stock wire with some big mondo cable, a careful
consideration of the system should be undertaken.  Recall the thread awhile
back where the guy installed a 1-wire alternator and wired it with welding
cable and promptly started smoking diode bridges?  This is a perfect example
of where the system designers relied on the wiring's resistance to limit the
peak current.  Remove that resistance by installing larger wire and something
else has to give.

I've been bitten by that same mistake.  I installed a higher capacity
alternator on my rig right after I got it.  I bypassed the stock wiring
harness with a short battery-alternator jumper of #4 wire.  I smoked a diode
bridge on the first trip.  Replaced the alternator on the side of the road.
Got no more than 50 miles before the second one smoked.  It dawned on me what
was happening.  After stopping for an over-night and using a few dozen
amp-hours of charge, the alternator was forcing max output into the battery
through that short fat wire, exceeding its continuous rating. I did another
road-side replacement, this time hooking the stock harness back up and have
had no problems since.  The 100 amp alternator can only force about 70 amps
into even a deeply discharged battery, something it can do more or less

For a larger inverter installation I'd do some simple measurements before
increasing the wire size.  I'd run the thing and see how hot the wire and
converter get.  A simple "hand thermometer" should be sufficient.  If either
are too hot to comfortably touch then they're too hot.  If the converter and
the wire get quite hot then one must move with caution in replacing the wire.
Larger wire will transfer some of that heat from the wire to the converter,
possibly overheating it.

IF the converter stays cool and the wire gets hot, then it is safe to increase
the wire size.  If you're not sure then a more scientific analysis is needed,
such as measuring the temperature rise in the converter, measuring the wire
temperature, computing the wire's power dissipation and then computing the
additional temperature rise in the converter caused by transferring the wire
dissipation to the converter.

It's hard to imagine a converter designed to rely on the hook-up wire to
protect it.  but then, few things surprise me in the RV world :-)

Boy, that got long-winded :-)

>BINGO.  I unplugged the supposedly nonworking charge wizard, and
>voltage dropped to 13.8 within a minute or two.  This is the normal
>charging voltage of the converter alone.  So that seems to be working
>per spec.
>I tried to cycle blind through the various modes of the CW, and no go.
>The lightless Charge Wizard is stuck in boost mode.

Now I'm starting to agree that the problem is in the charge wizard.  Best I
can tell from poking around inside the CW I have is that it controls the
charge voltage by toggling one of the lines in the interface connector.  That
jives with the manual equalization mode that can be invoked with a jumpered
plug inserted into the CW port.  Sounds like the CW is dead and is shorting
that line to ground just like the jumper plug does.

>Now this may be due to overheating the connection above the fuse, with
>the damage actually in the converter.  I guess buying another charge
>wizard and seeing if it works is the practical next step.  41 bucks,
>and they have to send off for it.   I could swear this thing was $25
>when I bought the first one at Camping World a couple of years ago.

I paid $25 for my CW at $CW$ a year or so ago.  Hmmm.  Poked around the web a
bit.  Looks like $CW$ is leading the rip-off way again.  I found a CW for
$23.39  here:

These guys

are tossing in the charge wizard for free with a PD converter purchase.  I did
NOT compare converter prices so that might not be "free" after all.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Intellipower Charge Wizard system
Date: Tue, 19 Oct 2004 01:38:27 -0400
Message-ID: <>

For anyone who wonders how the Intellipower converter and charge wizard
system works.

There are two patents, one a suppression of the other.  Both are extremely
well written and understandable to an electronics person.  Rather than try
to post the ungodly patent office URLs, I suggest going here:

And typing in the numbers.


I have sacrificed a Charge Wizard (at least the case) so I could put it in
the bench and figure out how it works.  These  patents seem to correspond
quite closely to what I'm observing.

It looks like the Charge Wizard could be used with most any DC power
supply that has either a remote voltage setpoint input or remote sensing.
I have some 20 amp switchmode supplies that I'm going to try this on as
soon as I get it all figured out.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Intellipower Charge Wizard system
Date: Wed, 20 Oct 2004 22:39:35 -0400
Message-ID: <>

On Wed, 20 Oct 2004 13:03:51 -0500, Dave Martin <dmartin@newarts.com2>

>Neon John said...
>> It looks like the Charge Wizard could be used with most any DC power
>> supply that has either a remote voltage setpoint input or remote sensing.
>> I have some 20 amp switchmode supplies that I'm going to try this on as
>> soon as I get it all figured out.
>Thanks John.
>My measurements of a PD 9140 with Charge Wizard shows the "boost mode"
>current rolls off starting at something like a 13.5+ terminal voltage
>and is zero at about 14.5 IIRC.

The little card that came with the Charge Wizard and the patent I cited
says that the voltage setpoints are as follows:

Storage mode  13.2
Equalize (desulfate) 14.4
Boost mode 14.4 for 1 hour, then normal mode
Normal mode 13.6

>Is this a characteristic of the Charge Wizard or of the PD converter?

Not sure yet.  See below.

>Also, would you share the pin out of the Charge Wizard?

Looking into the charge wizard connector with the cord exiting down and to
the right and with the empty socket on the lower left, the pinout is as

Upper left  power
Upper Right  out
Lower Right Ground

I haven't sketched the whole circuit yet but it appears that the power
input is both the sense lead and power for the PIC processor.  The PIC
processor gets its power from a 3 terminal voltage regulator fed from
"power".  I assume this lead is attached to the converter output and
measures the battery voltage.

"Out" is fed from 2 bits on the PIC through resistors that form a crude 2
bit A/D converter.  According to the above table, they're using 3 of the 4
possible states.  The output is also pulled up by a resistor fed from
"power".  The 2 "bit" resistors are 117k & 12.2k, and the pullup resistor
is 150k, all high precision resistors.

Since I don't know what is in the Intellipower, I'm not sure what the
output comprises.  It could be the actual setpoint for the Intellipower.
Or it could be a "quadrastate" analog signaling means for selecting
operating states in the Intellipower.

Since the 150k resistor is connected to the battery voltage, there is some
feedback involved which makes me think that the output of the Charge
Wizard is the actual setpoint voltage for the Intellipower.

Something that would be very useful to me is for you to measure the "out"
voltage in the various modes and report them here.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Winter Storage for Batteries
Date: Wed, 03 Nov 2004 01:16:20 -0500
Message-ID: <>

On 01 Nov 2004 13:49:00 GMT, (Dfrenchy) wrote:

>I have 2 golf cart and one 12 volt battery which I plan to hook up to one 6 amp
>charger with a timer. I am thinking of charging them 30 min a day. Does this
>sound like a good plan????? Yes, the 6 volt ones will be in series.
>Don in midcoast Maine

You might want to take a look at the IDEAL wall-wart based intelligent
charger here:
about half way down the page.

I have probably 25-30 12 volt AGM batteries of various sizes and a couple
of golf cart 6 volt batteries that I use for my EV and E-scooter work.  I
have one of these chargers for each pair of AGM batteries hooked in
parallel and one charger for the 6 volt batteries hooked in series.  I am
completely satisfied with the performance.  It has kept some of these
batteries fresh and at full capacity for a couple of years now.  At $19.95
ea, the price is right.

This is an impulse type charger where full charge current is supplied
until the voltage reaches a setpoint.  No current flows until the voltage
drops to the low threshold setpoint.  With a 17AH AGM battery, the charger
pulses on for a few seconds every 15 seconds or so.  With the golf cart
batteries it pulses on for about 30 seconds a couple of times an hour.  No
gassing and no water usage.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Victor VEC 1093 A question
Date: Sat, 04 Jun 2005 13:09:24 -0400
Message-ID: <>

On Fri, 03 Jun 2005 17:28:09 -0400, Frank Tabor
<> wrote:

>>Hate to disagree, but I did ask Neon John that identical question
>>before buying my eu2000 and Vector 1093. He assured me that charging
>>via Vector, and being plugged in to the generator at the same time
>>would be fine. I have now done it several times, and it works great!
>>When charging, the wife can also use the microwave, or vacuum, or
>>whatever. It was also suggested that I only charge the battery(s)
>>until the charge point went down to 10 amps or so, that being the
>>point at which the battery is mostly charged, but not quite. After
>>that you reach the point of diminishing returns on how long you run
>>the generator vs. how much more charge the  battery gets. I have done
>>several outings now using that method, and it works like a charm. Only
>>when I get home do I let the charger do a complete charge to the point
>>where it shuts off. On the average, that method keeps my jenny usage
>>to about half an hour a day, sometimes a little more.
>Ok, like I said, I was concerned about the two chargers confusing each

A little late on this thread.  Sorry, I've actually been working....

Recently I had the occasion to connect both the Vector and the
Schumacher charger to my truck's batteries.  I'd left a light on, run
down the pair of large diesel cranking batteries and had a delivery to
make.  I needed to charge this set FAST and my CBC was otherwise

I found that the Vector would share the task without complaint while
the Schumacher required babying.  I had to connect the Schumacher
first and let it run for a few minutes before gradually bringing the
Vector up, one amperage step at a time.  Ultimately they both cranked
their almost 40 amps each into the batteries without complaint.  It
took a good 30 minutes' charge to get enough juice into the batts to
turn over the engine.

My only concern about leaving the Vector connected all the time would
be the possible damage from transients as the generator starts and
stops.  My Vector has seemed bulletproof so far but I keep thinking
about those little diodes in the AC input circuit....  The
Schumacher's power factor correction circuitry apparently does not
like anything other than 60 hz.  I'm fairly certain that off-frequency
power is what smoked two of 'em in a row when operated from an
inexpensive generator.

If you have an automatic changeover relay that lets the generator come
up to speed and voltage before connecting the trailer then there
probably won't be any problem.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: My Yamaha Generator Arrived Yesterday
Date: Thu, 15 Dec 2005 12:34:19 -0500
Message-ID: <>

On Wed, 14 Dec 2005 14:33:13 -0800, wrote:

>Get a smart charger, plug it into the Generator, and within an hour or
>so, you'll have plenty of juice.
>is a good example of such a charger. Many of us here use this one with
>great results. The Vector 1093 (above link) many times can be had new
>for $90, or some refurbs around for $60.
>I have a refurb 1093, and it works great.

As the one who turned this group onto the Vector, I have a couple of
comments.  First, Black and Decker is private labeling the Vector and
selling it through WalMart.  The linage is obvious when you see one
out of the box.

Second, as much as I like and use my Vector, for an RV I'd spend the
little extra money necessary to get a Progressive Dynamics
Intellicharge and Charge Wizard.  This combo does the same sort of
smart charge as the Vector.  It also does several more things.  It is
fully automatic.  Just hook it up and forget about it.  Apply 120vac
and it starts charging.  The charge wizard does a periodic
equalization charge which extends battery life.  Finally, for folks
trying to minimize generator run time, it's available in up to 80 amp

I balanced price vs performance and bought the 60 amp version for my
MH.  It does a wonderful job.  I also have a 40 amp unit that Bob
Gidding gave me that was defective.  I repaired it, equipped it with a
power cord, an ammeter and a pair of battery clips and use it as a
portable charger.  I glued the Charge Wizard to the top of the box.
Speed is comparable to the Vector but it's all automatic.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: My Yamaha Generator Arrived Yesterday
Date: Fri, 16 Dec 2005 14:40:40 -0500
Message-ID: <>

On Thu, 15 Dec 2005 11:32:52 -0800, wrote:

>>Second, as much as I like and use my Vector, for an RV I'd spend the
>>little extra money necessary to get a Progressive Dynamics
>>Intellicharge and Charge Wizard.  This combo does the same sort of
>>smart charge as the Vector.  It also does several more things.  It is
>>fully automatic.  Just hook it up and forget about it.  Apply 120vac
>>and it starts charging.  The charge wizard does a periodic
>>equalization charge which extends battery life.  Finally, for folks
>>trying to minimize generator run time, it's available in up to 80 amp
>>I balanced price vs performance and bought the 60 amp version for my
>>MH.  It does a wonderful job.  I also have a 40 amp unit that Bob
>>Gidding gave me that was defective.  I repaired it, equipped it with a
>>power cord, an ammeter and a pair of battery clips and use it as a
>>portable charger.  I glued the Charge Wizard to the top of the box.
>>Speed is comparable to the Vector but it's all automatic.

>Roughly, how much for a setup like yours? Sounds good.

The 40 amp Intellicharger is listed at $149 at $CW$.  Add $20 for the
Charge Wizard.  The 60 amp version is $199.  I'm sure that price can
be beaten but $CW$ is where I go to find a typical price.  That's all
you need to install it in your RV, other than maybe a little hookup

To turn one of these into a portable battery charger, you'll need the

AC power cord                      $1-$5
1/2 of a jumper cable set          $10-30
Ammeter*                           $10
Carrying handle                    $2

* I use the "inductive" type ammeter.  This is a little test meter
that can be bought at most any car parts store.  The wire is laid in
the groove in the back and the meter pointer is deflected by the
magnetic field associated with the current flow.  This meter is very
compact, very rugged and doesn't require cutting the cable.  BTW, this
is a very handy test instrument to have around.  It responds equally
well to AC and DC and, IMHO, more accurate than at least the cheaper
clamp-on meters.

I pick up AC power cords at hamfests and swapmeets, never more than a
buck apiece.  The cord I used on this unit has an in-line switch which
saved me the cost and the trouble of a separate switch. I use a
hardware store cabinet handle for the carrying handle.  I simply sheet
metal-screwed it to the top of the Intellicharger. For the 40 amp
unit, 2-4 gauge jumpers are fine.  I try to find the 15-20 ft long
ones so I can cut them in the middle and have 2 sets of useful length.

I'm going to add a digital panel meter voltmeter as soon as the
hamfest season starts again in February and I can buy one very
cheaply.  I'm also thinking about adding voltage adjustment pots for
each charging stage so I can set it, for example, to a gell cell or
even some wet NiCads I have.

I need to get a web page up on this conversion.  Maybe over Christmas.
I'm taking a 10 day vacation :-)

BTW, I've figured out how to take a Charge Wizard and adapt it to any
DC power supply with an adjustable output voltage and turn it into a
smart charger.  Twelve to 15 volt, 10-30 amp switchmode power supplies
turn up all the time at hamfests, swapfests, sleazebay and so on,
usually in the $20-50 price range.  Though not as common now since
minicomputers have been displaced by servers, one can still find
surplus 5 volt, 100 amp power supplies dirt cheap, in the $5 range.
Three of these in series makes one kick-*ss charger.

If anyone is really chomping at the bits to make a charger using the
Charge Wizard, email me and I'll write up a description.  Otherwise,
wait until I get it on my web page, complete with schematics and


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: More Battery Recharging Questions
Date: Wed, 21 Dec 2005 23:47:19 -0500
Message-ID: <>

On Thu, 22 Dec 2005 01:49:37 GMT, wrote:

>On Wed, 21 Dec 2005 15:15:17 -0500, Neon John <> wrote:
>>Golf Cart batteries tend to be fairly high impedance so the bulk phase
>>will end relatively quickly, usually around 50-60% of the total charge
>>required.  Let's assume 60%.
>>The bulk phase will take (130*.6)/40 = 2 hours. That will have
>>returned about 130*.6 = 78 ah.
>Whoa!!!  Deep cycle batteries are not built like car batteries and do
>not like fast charging.  Generally the recommended max rate of charge
>is a C/10 - C/20 is better.  A C/10 charge for a 225aH set would be
>22.5 amps.  A C/20 is about 11 amps.
>I didn't pay as much serious attention to this in the past as I do
>now, after pressing my system into use for the power outage from
>Hurricane Wilma.  I had stuck the dip switches in the wrong position
>on my Trace smart inverter/charger when I added batteries, and charged
>at a much higher rate with my generator than I normally use.

I have no idea what wrong DIP switch settings did to your battery but
I know for certain that fast, intelligent charging does not harm these
batteries.  I and many other EV owners prove that every day.  I have a
72 volt, 70 amp charger on my EV that uses these same batteries and
they've been happily puttering along for over a year and a half now
with no loss in range.  I installed a larger than stock charger.  The
stock charger was 50 amps.  I know more than one owner of my model EV
who is going on 7 years on his pack.

Further experience more directly applicable to RVing.  I have two
Group 29 12 volt batteries in my MH.  They're about 3 years old now. I
mostly dry-camp. The majority of the time they're charged at 150 amps
during the bulk phase by my CBC (cordless battery charger.)  When
they're charged from shore power, the 60 amp PD Intellicharge/Charge
Wizard does the job.

These batteries have lost about a third of their capacity but NOT from
fast charging.  They have about 250 cycles on them, many cycles below
80% DOD.  Batteries are so cheap that I don't care much about overall
life.  I have limited battery space and I want all the amp-hours I can
get out of that space.  So I "abuse" them, at least by conventional

Fast charging will NOT warp plates, no more than fast discharging
will.  OVER-fast charging, IE, fast dumb charging can cause plate
swelling if the over charging is excessive.

Trojan will tell you, if you call, get past sales to an engineer and
convince him that you a) know what you're doing and b) won't sue them
if you screw up, that their wet cell batteries suffer no life
degradation at C/2 charge rate with a smart charger and that an
initial rate of C is OK for a tightly controlled, temperature
compensated smart charger with programmable setpoints.

What damages wet cells is the formation of gas within the structure of
the plates at a rate faster than can recombine and diffuse out. During
the bulk phase, that is not a problem because the electrochemical
reactions are occurring on the surfaces of the plates. As the surface
conversion runs its course, the voltage rises as material deeper
inside the plates starts reacting.  The reason for the voltage rise is
the added resistance of the electrolyte paths through the plate pores
and the reduced surface area available.

When the voltage reaches a specified point, selected so that plate
internal gas production isn't too great, the bulk phase ends, the
charger goes to voltage regulation and the absorption phase begins.
During this phase the current gradually drops as the reaction proceeds
deeper and deeper into the plates.  When the current has dropped to a
fraction of the initial rate, the absorption phase is over, as most
material has been converted and most of the energy input is being
expended as heat and gas.  The trickle phase begins at a lower
voltage, a voltage selected NOT to cause gassing.  That stage finishes
off the last vestiges of sulfate.

All a higher bulk charge rate does is get through the bulk stage a
little faster.  When the voltage rises to signify the end of the bulk
phase, the battery controls the charge rate from there one, as the
charger's voltage is now regulated.

If my smart charger could put 1000 amps into a golf cart battery, the
only result would be the practically immediate termination of the bulk
phase because of the voltage drop across the internal resistance of
the battery.

AGMs are much better.  Hawker says that there is NO maximum charge
current for their Genesis line of AGMs. (There obviously is a limit
somewhere out there but Hawker isn't interested in debating semantics
with non-engineers.) Experience has shown that the Optima AGM also has
no limit.  I know some guys involved in EV drag racing that are
discharging 55 AH Optimas at 2000+ amps, are dump-charging from a
larger, higher voltage bank at 500+ amps between heats and are on
their 3rd season with the pack.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: More Battery Recharging Questions
Date: Fri, 23 Dec 2005 12:51:51 -0500
Message-ID: <>

On Fri, 23 Dec 2005 05:54:31 GMT, "BF Lake" <> wrote:

>"Neon John" <> wrote in message
>snip very helpful info, thanks.
>> When I foolishly changed to a pair of 6 volt cart batteries, I found
>> that the bulk phase ended before 50%.  Another hour on absorption
>> would only get to maybe 60-65%.  Completely unacceptable for my way of
>> camping.
>That's where I am having trouble I wasn't expecting with my new batteries
>and my fancy new charger.  When my pair of 6v U2200s are down to ~50% or
>somewhat less, and I recharge with the Vector 1090A (20/10/2) it  will take
>~ four and a half hours to do its "smart" routine.  It then says they are
>"full" but the hydrometer says they are at ~75%.

This why I don't use a hydrometer on a regular basis.  The free space
electrolyte SG lags far behind that between the plates.  If you could
leave the batteries alone for a day, the SG would rise significantly
as the liberated acid slowly diffuses out.

A hydrometer is good for batteries that have been sitting for awhile
or batteries constantly on float charge, such as large standby
batteries.  For highly dynamic batteries like ours, the hydrometer is
more of an annoyance.

>Drives me nuts.  Vector
>says the 1090A (14.5v) cannot fully charge 6v batteries because they would
>need over 15 volts to top off.    Anyway we are getting by ok but I have
>learned to recharge every day instead of every second day( in summer) to
>reduce the time it takes for the 1090A to go through its routine.

I think there may be a matter of semantics involved here. Technically,
to completely and fully charge the battery and equalization cycle is
necessary.  That overcharges the strongest cells to bring the weakest
ones fully up.  The strong cells gas and the weak ones charge.
Equalization takes 15+ volts, depending on temperature.

Our conventional definition of "fully charged", that is, when the
battery is accepting no more energy on trickle charge, is done just
fine with the Vector.

After working with dozens, maybe hundreds of battery systems over the
years, I've observed that the absorption stage in wet deep cycle
batteries takes about 3 hours regardless of the size of the battery. A
function of plate geometry, I think.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: More Battery Recharging Questions
Date: Fri, 23 Dec 2005 16:09:51 -0500
Message-ID: <>

On Fri, 23 Dec 2005 18:45:12 GMT, "BF Lake" <> wrote:

>"Neon John" <> wrote in message
>> This why I don't use a hydrometer on a regular basis.  The free space
>> electrolyte SG lags far behind that between the plates.  If you could
>> leave the batteries alone for a day, the SG would rise significantly
>> as the liberated acid slowly diffuses out.
>Once again, I am grateful to have this cleared up.  I have been putting the
>batteries on the 7355 when home and noticed that a couple days later the
>hydrometer says they are now really "full"  I thought  it was the 7355
>topping them off .  So now I can feel better about my Vector .  :)

You're welcome.  After some fairly extensive testing, I consider that
vector line to be among the best chargers on the market as far as the
battery is concerned.  I don't like having to start the thing manually
each time.  But it sure does a battery good.

>> A hydrometer is good for batteries that have been sitting for awhile
>> or batteries constantly on float charge, such as large standby
>> batteries.  For highly dynamic batteries like ours, the hydrometer is
>> more of an annoyance.
>Especially when there isn't enough clearance over the batteries in their
>compartment to wield the hydrometer.
>This also negates the "disadvantage" for AGMs where you can't measure their
>state of charge when they have just been charged by checking their voltage
>(surface charge), and you can't use a hydrometer.

The only two disadvantages of AGMs that I know of are the cost and
that they require more attention to charging.  You can't let it sit
there with a high voltage dumb charger and boil away for months at a
time.  Other than that, I love 'em.

>> Our conventional definition of "fully charged", that is, when the
>> battery is accepting no more energy on trickle charge, is done just
>> fine with the Vector.
>All I need to do is redefine "full" from 100% to a lower number, and my
>anxieties will go away <G>.  I wonder if their amphr rating capacity is
>measured from 100% or from a lower "full" too?
>> After working with dozens, maybe hundreds of battery systems over the
>> years, I've observed that the absorption stage in wet deep cycle
>> batteries takes about 3 hours regardless of the size of the battery. A
>> function of plate geometry, I think.
>I saw where you said that going from a 20/10/2 to a 40/etc would only
>shorten the time for the bulk stage, so I inferred that once you have paid
>for a new 20 amp one there is no point paying again to get a 40 .(?)  On the
>same lines, is there any real point in trading in a quite new 7355 for a PD
>with charge wizard?

I have enough experience with golf cart batteries now that I think I
can say with certainty that the benefits will be much less than if you
had several 12s (AGM or wet) in parallel.  In addition to my MH
batteries, my EV has 72 volts' worth of cart batteries.  For various
reasons I've had to charge the pack as sets of 12 volt batteries on
numerous occasions.  My little car looks like it's under attack from
an octopus with all the chargers and wires hanging off it :-)

These behave just like the ones in my MH did.  Early transition from
bulk to absorption.  The higher current of those chargers would not
help all that much unless you deeply discharge the pack between
charges.  With the relatively high internal impedance, it takes more
voltage to force more current.  All that extra voltage does is heat
the battery and electrolyze the electrolyte.

I've tried the extra voltage approach despite my knowing that the
chemistry involved says it wouldn't work.  I just had to see :-)

I set the bulk/absorption transition point on my CBC to 16 volts and
fired it off.  The CBC quite merrily cranked 150 amps into the
batteries for some time, tapering off to about 100 amps.  The result?
The batteries were on their way to thermal runaway when I shut down
the test and a good chunk of electrolyte had been ejected from the
violent gassing.  Worse, the experiment didn't return a lot of charge
to the pack.  I went ahead and charged them conventionally and saw
little difference.

One thing you CAN do to minimize the total run time of your generator
is charge in more than one sessions.  I've verified this by
experiment.  Stopping the charge, waiting awhile and then continuing
again lets the electrolyte equilibrate within the plates.  If you stop
the first charge around the time of bulk/absorption transition, when
you return after a delay you'll find that the charger again runs in
bulk mode for quite some time.  Frequently almost as long as the first
time.  I haven't experimented to determine the optimum number of
intervals but I'd guess 2 to 3 with maybe an hour or 2 between

If you do a lot of dry camping and want to get the maximum possible
amount of energy from the battery space you have, you might want to
consider wet NiCads.  The BB600 jet engine starting battery is widely
available surplus.  Here is a source:

34ah, 1.25 volts per cell.  $10/cell.  Service life is rated at 30
years but the practical lifetime is far longer.  Effectively a once in
a lifetime purchase.  I have a 28 volt jet start pack of Korean war
vintage that still has its rated capacity.

There are so many advantages.  The wet NiCad requires no special
charging algorithm.  It can be run completely flat.  In fact the
normal mode of storage is flat with the terminals shorted.  Moderate
overcharging is harmless.  In fact, it is recommended to charge to
gassing on each charge.  The voltage is practically flat until total
discharge.  VERY low impedance - a single 34ah pack can source
thousands of amps for a significant period.  They parallel well with
no special precautions required.  The potassium hydroxide electrolyte
is almost non-corrosive to ferrous metals and is much less corrosive
to skin than sulfuric acid.  Plus it is quickly neutralized in air by
the CO2 in air.  In fact, the only maintenance necessary on these
batteries other than watering them is replacing the electrolyte every
5-10 years as infiltrating air weakens the electrolyte.

The only disadvantage is cost.  But that cost equals out after the
second or third Pb pack.

I'm going this route the next time.  I think I'll start with 6 12 volt
strings in parallel for a total of 240 AH.  At 10 cells per 12 volt
string, that's 60 cells. I imagine $5-8 each in that quantity will get
them.  If so, about $480.  If that isn't enough storage capacity then
I'll add a couple more strings.  If I go this route then I'll remove
them when I sell the rig and take them to the next one.  I'm also
saving my money for a NiCad pack for my EV but that's down the road a

Another advantage of these cells is that since they ARE individual
cells, the battery can be spread out over any available space.  A few
tucked here, a few tucked there and so on.  About the only
complication is that the connectors have to be nickel.  Copper is
corroded by KOH.

A huge lot of these came up for sale mil surplus back in the summer.
Many EVers bought them.  All are completely satisfied with the


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Another Battery Charging Question
Date: Mon, 06 Mar 2006 01:09:09 -0500
Message-ID: <>

On Sun, 05 Mar 2006 17:45:03 GMT, "B F Lake" <>

>I notice my Vector 1090A says it wants 120AC and 335 input watts.  It also
>has some sort of compensation for lower voltage and will still work.
>I now use this with a generator or shore power.  Can I also put my cheapo
>400 watt  inverter on the truck's battery and plug in the Vector to charge
>my trailer batteries?  (truck engine running). (I don't know the sustained
>wattage of the inverter but maybe at least 335??)
>I am assuming the Vector would do its usual, and be better than using the
>other two ways to charge from the truck: booster cables battery to battery
>or using the towing cable.

You'll have to try it to see if your 400 watt inverter really will
handle the load.  But yes, you can indeed plug the Vector to an

I did that very thing recently when I found the battery in my 68 Fury
dead.  It was sitting right beside my GMC MD truck that has a 1500
watt inverter permanently mounted.  It was easier to hook up the
Vector and a short extension cord than to muck around with anything
else.  It worked just fine.

The Vector doesn't care what waveform it receives.  In fact, it'll run
on DC if the voltage is anywhere from about 140 to 200 volts. I'm not
suggesting anyone try this but.....  I have tested mine after looking
the PCB over.

Little known fact outside the electric vehicle world: Most switchmode
power supplies, particularly those that handle 120 and 240 without a
switch or jumper change, work just fine on DC.  Many folks with EVs
with pack voltages between about 140 and 300 volts DC are using
switchmode power supplies to provide the vehicle's 12vdc for


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Another Battery Charging Question-Answer!
Date: Mon, 06 Mar 2006 19:44:13 -0500
Message-ID: <>

On Mon, 06 Mar 2006 22:33:39 GMT, "B F Lake" <>

>Ok, I tried it.  Didn't wait to hear back from Vector.  The Vector did not
>fry.  It worked great!  Here are the numbers:

Kewl!  I doubt that you'll hear back from Vector.  I never have.

>   So this is too neat.  You are dry camping and want to charge your
>batteries in the morning when quiet hours are over so you can run the truck
>(gas engine) but generators aren't allowed or you don't have a generator,
>but you have a 400w inverter and a Vector. (if a 1093 40amp use the 20amp as
>max unless you have a better inverter) IMO it is better than the booster
>cables or the towing cable method to use the smart charger.  Truck running
>at idle issue is a wash--same for all three methods.
>I guess this is the poor man's version of the posh MH method using the fancy
>inverter with the built- in smart charger.

Yup.  As I mentioned in another post, I've had my MH configured like
that ever since I got the 60 amp PD Intellicharge.  I have an old 1kw
Vector inverter connected to the chassis alternator/battery which runs
the 60 amp PD just fine.  I'm going to replace it with a Sam's
Club/Vector 1500 watt inverter after I next visit Sam's Club.

The new Vector has one majorly good new feature - auto-reset after
over or under-voltage trip.  The old one trips fairly often from
over-voltage when the engine is running, the chassis battery is
charged and there is a significant load on the alternator such as all
the light and the heater fan.  I have to manually turn the inverter
off and back on to reset the fault.  The new one auto-resets when the
voltage drops within the specified operating range.

I thought about rigging a contactor and some heavy cable to switch the
house inverter to the engine but given the $79 cost of the Sam's unit,
it's cheaper just to install a second one.  And more satisfactory
since my 'fridge is a compressor one that runs on the house inverter
all the time, even on shore power.

I should mention again that I have smoked two different Schumacher
smart chargers trying to run them from my 1kw Chicom non-inverter
generator.  The generator output isn't very clean though better than
these cheap inverters.  Apparently the input of the Schumacher is very
particular about the waveform.  I think this has something to do with
the charger's input PF correction circuit. I haven't tried one on an
inverter and don't plan to since I'd expect instant blue smoke.


From: John De Armond
Newsgroups: misc.rural
Subject: Re: Charging Batteries
Date: Wed, 19 Apr 2006 01:49:48 -0400
Message-ID: <>

On 18 Apr 2006 08:58:00 -0700, "Larry Caldwell" <>

>Neon John wrote:
>> Please don't post a URL to that one.... Ignorance sometimes is painful
>> to read...
>> One can charge a conventional lead-acid battery at 1C or more (that
>> is, the amp-hour capacity expressed in amps) with absolutely no danger
>> to the battery IFF the proper controls are in place.  If this
>> knucklehead is forcing current until he is heating the battery then
>> he's killing it.
>Maybe I wasn't clear.  The article was specifically about batteries
>that are dead, or almost dead.  The guy seemed to think that many
>batteries discarded as dead were actually salvageable by charging them
>for a short period of time at a high rate.

OK, I agree with that.  I've used several methods of bringing dead
batteries back.  heavy charging like that.  Heavy reverse charging for
a little while.  Desulfator pulsers (works well).  EDTA treatment
(also works well if there is enough active material left after the
EDTA gets rid of the sulfate) and even just really long term charging
at higher than normal voltage, supplying water as necessary.

A dead battery is still pretty much on its last legs but one can get
by.  The pulser and the EDTA work best.  My "bench battery" is a pair
of golf cart batteries that got too weak to service my motorhome. I've
had a desulfator pulser operating on them continuously since I removed
them from my MH 3 years ago.  When I do a discharge test on them using
this gadget:

I'm still getting about 100 ah out of them.  That's a little less than
half the nominal 220 ah rating.  Not bad for almost 8 year old
batteries.  Good enough to run anything on the bench that I'm likely
to work on.

The particular pulser is called the Battery Minder.  It is a
combination of a 1 amp trickle charger and a desulfator pulser.

When I did a product test in this thing, I let it assault a 120 ah
Group 29 deep cycle battery that had declined to just 20 ah, despite
repeated chargings and discharging.  After 2 weeks of pulsing the
Minder brought the battery back to 80 ah.  The funny thing is, if I
let the battery just sit in a charged state, the capacity fairly
rapidly drops again.  That is, it will hold much less energy despite
being charge and discharged.  If I leave the pulser hooked up or
simply use the thing, either charging or discharging, the capacity
stays right up there.

Batteries!  As finicky and as deep a mystery as women :-)

>Thanks for the discourse on battery charging.  I didn't really
>understand all of it, but it gave me some directions to go for further

You're welcome.  Here's another good discussion:

This guy is mostly marine-oriented but his information and his
products are good.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Looking for battery recommendation
Date: Thu, 11 Jan 2007 13:18:57 -0500
Message-ID: <>

Hi Dave,

I can't answer about the Honda generator.  My cheap-sh*t Chicom 1kw
generator will run it just fine but I don't know about that expensive
honda :-)

I did want to comment about the charger.  I'm the one who discovered
the Vector, bought it, tested it and reported here.  That got others
buying it.  It's a wonderful charger and I still use mine quite a bit
but for RVing it has one major fault and two minor ones.

The major fault is that you have to push buttons to get the charger to
start.  It won't start of its own accord when power is applied.  That
precludes hiding the charger in a cabinet or something.  It has to
remain accessible.

The first minor fault is that it won't pick up any load applied to the
battery.  If you apply, say, a 20 amp load (furnace, some lights, etc)
and it is connected, it'll resume trickle mode (about 5 amps) but you
have to push buttons again to get it to resume full output.  It's
designed for one-shot charging where you hook it up, charge, then

The second minor fault is that it requires something like 6-9 volts on
the battery to start.  If you inadvertently flatten your battery pack
then you'll have to use some other charger to pull the pack up enough
to get the Vector to start.

If you don't mind spending just a little more money then the
Progressive Dynamics Intellipower with Charge Wizard is much more
suited for RV use.  It also does a smart charge but it starts
automatically when power is applied, has full output available at all
times and will charge a completely dead battery if it can be charged.

Here's PD's factory store where they sell factory refurbs.

I just bought an 80 amp version of the PD9200 for my MH and am quite

The PD9200 series has the charge wizard built in while the 9100
doesn't.  If you get the 9200 you'll want to get the monitoring
pendant too.  If you go with a 9100, look elsewhere for the Charge
Wizard, as it can be had for about $20.  Check  He usually has great prices on PD

As you can see, a 45 amp Intellipower is only about $50 more than the

About a year ago I converted a 60 amp IP into a portable charger. This
involved adding the cable and one set of clips from a set of jumper
cables to the output, adding a 60 amp ammeter, attaching the Charge
Wizard to the case with clamps, attaching a handle and adding a
longer, better power cord to replace the factory cheap-sh*t PVC cord
that goes rigid in cold weather.

This is a wonderful battery charger.  I have it here in my semi truck
right now.  I have a large AGM battery in the truck that I use to run
my electric blanket and refrigerators.  The Intellipower is connected
to the AGM and plugged into my 1500 watt inverter.  When I get
underway after a sleep period, I simply turn the Intellipower on and
it quickly charges the AGM, then supplies power to the 'fridges.  Yes,
I could have simply hooked the AGM to the vehicle's 12 volt system but
that wouldn't charge the battery nearly as fast, nor would it do the
kind of intelligent charge necessary for long battery life.  With over
$200 sunk in this battery, that's important!


On 11 Jan 2007 08:36:09 -0800, "Dave" <> wrote:

>If I go with the Vector VEC1093 charger, will my 1kW Honda generator
>have enough juice to run it at 40A?
>BF Lake wrote:
>> "Dave" <> wrote in message
>> > I need to replace the two 12-volt deep cycle batteries on my 2002 24-TS
>> > Komfort trailer. Wondering if anyone has any recommendations for
>> > brands/types.
>> Don't forget the charger.  If you get golf cart batteries (do) you need a
>> better charger than your 7355 has.
>> The good  batteries are great for lasting and lots of amp hrs but then  they
>> are  correspondingly tough to re-charge.
>> A Vector/BD  1093 (has the 40amp bulk rate) would be an excellent choice
>> IMO.
>> Regards,
>> Barry

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Battery Chargers--General Purpose
Date: Wed, 31 Jan 2007 15:36:06 -0500
Message-ID: <>

On Wed, 31 Jan 2007 10:26:05 -0800, wrote:

>Probably. My Vector refuses to charge anything that has less than 4 or
>5 volts in it. So, out comes the dumb charger for five minutes or so.
>That brings it up enough so the Vector will do it. Why they work that
>way is a mystery to me, and I wish they wouldn't.

Probably an easy way to protect against shorts on the output and/or
very low voltage loads that could exceed the dissipation of the output

Exide made/makes a line of "bang-bang" smart chargers (full charge
voltage is pulsed on and off to maintain the battery instead of a
second voltage stage) in which the charger electronics themselves are
powered from the battery leads.  No battery in place, no electronics
operations and no output.

I reverse-engineered the PCB and thought the design novel enough that
when I ran into an Exide engineer on the net I asked about it.  He
confirmed my suspicion, a cheap and clever way to ensure the charger
is hooked to a battery of the proper voltage.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Battery Questions
Date: Sun, 18 Mar 2007 14:55:49 -0400
Message-ID: <>

On Sun, 18 Mar 2007 10:05:59 -0700, Mickey <> wrote:

>BF Lake wrote:
>> No, that is the current the battery is getting for charging amps.  During
>> the absorption stage the voltage is  fairly steady at 14something while the
>> amps drop off as the battery charges up (ie as resistance rises)
>> .....
>> Regards,
>> Barry
>See its time to hit the books again.  Battery resistance, impedance,
>does not rise as the battery is charged, it does exactly the opposite.
>Your statement is saying a batteries ability for electrons to flow
>either in or out is at its min when fully charged.  Not only does this
>not make sense, it's wrong.
>The drop in charge rate in a constant potential (voltage) charge scheme
>is due to the rise in the battery voltage, thus reducing the delta V
>(voltage difference) so the charger has less pressure (voltage) to push
>electrons in the battery.

Correct.  The difference between the bulk and absorption stage is
strictly one of definition.  The battery voltage steadily rises as it
charges at a constant current (bulk stage).  At some voltage point,
chosen as a balance between speed of charging, heating, gassing and a
few other parameters, the voltage is no longer allowed to rise
(constant voltage.)  The battery continues to charge at a diminished

Also correct that the impedance of the battery decreases during the
charge.  In fact, impedance is the only external measurement that can
reveal approximate state of charge.  That's what the very expensive
and fancy state-of-charge test instruments rely on, an impedance
measurement.  Not terribly accurate (even though some of the
instruments display to one decimal place!) but better than SWAG.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Battery Questions
Date: Sun, 18 Mar 2007 18:08:17 -0400
Message-ID: <>

On Sun, 18 Mar 2007 20:53:54 GMT, "BF Lake" <> wrote:

>"Neon John" <> wrote in message
>> On Sun, 18 Mar 2007 10:05:59 -0700, Mickey <> wrote:
>> >BF Lake wrote:
>> >> No, that is the current the battery is getting for charging amps.
>> >> During the absorption stage the voltage is fairly steady at
>> >> 14something while the amps drop off as the battery charges up (ie as
>> >> resistance rises)
>> >See its time to hit the books again.  Battery resistance, impedance,
>> >does not rise as the battery is charged, it does exactly the opposite.
>> >Also correct that the impedance of the battery decreases during the
>> >charge.
>I admit I never did understand impedance, but I think it has to do with
>alternating current , not DC?  Not sure how that applies in a battery.  Also
>I vaguely remember it is the opposite of resistance, so if a battery does
>indeed have impedance, and it is going down during charging, then isn't
>resistance  going up??

Impedance refers to both the real (resistive) and imaginary (inductive
and/or capacitive) parts of a complex device's terminal
characteristics.  DC resistance is a specialized case of impedance
applying to pure resistance.

Impedance is the proper term to refer to the internal characteristic
of a battery that resists current flow.  There is both an inductive
and a resistive element to the simplest model of a battery.  The
ability of a battery to deliver current is partially dependent on how
rapidly that demand appears.  Though there is no inductor inside the
battery, inductive reactance is the easiest way to model this
behavior.  The actual source of this time-dependent behavior is very
complex and has to do with reaction rates, among other things.  Too
complex for me to try to get correct in a Usenet post.

Two real-world examples of where this matters are a) non-DC/DC
inverted 12 volt stereo amps and EV motor controllers.  In both cases
it is typical to include low ESR capacitors close to the
semiconductors to reduce the AC impedance of the battery.

Here's a paper that addresses battery electrical models:

Here is a patent application regarding battery modeling:

This site requires a login to see the images.  Use, PW: patents.

This is an area of intense interest to me, as I'd like to do better
than the E-meter/Link-10 does with its simple linear model with
Peukert compensation.  I want to be able to look at a display and
have, say, "25% charge remaining" actually mean something.

As you can see, modeling a battery is VERY complex.  Especially when
trying to determine state-of-charge.  Kinda illustrates how silly the
"voltmeter method" really is.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Battery Questions
Date: Mon, 19 Mar 2007 14:43:34 -0400
Message-ID: <>

On Mon, 19 Mar 2007 08:14:40 -0700, Mickey <> wrote:

>What you're overlooking is while the charger is a fixed voltage the
>battery voltage is variable and it's the voltage difference which along
>with the battery resistance/impedance (which is quite small) that
>determines the charge rate.
>The charger is trying to push one way and the battery is pushing the
>opposite way, balance of forces. Didn't know you level of knowledge of
>things electrical and that is why I use the siphoning example.

Correct.  The battery's internal impedance simply isnt' a factor.
Consider:  A golf cart battery can supply 400 amps while dropping its
terminal voltage to about 5 volts.

5/400 = 0.0125 ohms or 12 milli-ohms. That's pretty high as batteries
go. A run of the mill AGM will be 10x less.  That changes as the
battery charges and discharges and it also changes with current
magnitude but not enough to have any effect on the charge current.
It's strictly the rising EMF of the battery opposing the charge
voltage that governs charge current.


From: GaryO < @ . >
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Battery Questions
Message-ID: <>
Date: Mon, 19 Mar 2007 21:39:05 GMT

On Mon, 19 Mar 2007 14:43:34 -0400, Neon John <> wrote:

>On Mon, 19 Mar 2007 08:14:40 -0700, Mickey <> wrote:
>>What you're overlooking is while the charger is a fixed voltage the
>>battery voltage is variable and it's the voltage difference which along
>>with the battery resistance/impedance (which is quite small) that
>>determines the charge rate.
>>The charger is trying to push one way and the battery is pushing the
>>opposite way, balance of forces. Didn't know you level of knowledge of
>>things electrical and that is why I use the siphoning example.
>Correct.  The battery's internal impedance simply isnt' a factor.
>Consider:  A golf cart battery can supply 400 amps while dropping its
>terminal voltage to about 5 volts.
>5/400 = 0.0125 ohms or 12 milli-ohms. That's pretty high as batteries
>go. A run of the mill AGM will be 10x less.  That changes as the
>battery charges and discharges and it also changes with current
>magnitude but not enough to have any effect on the charge current.
>It's strictly the rising EMF of the battery opposing the charge
>voltage that governs charge current.


I think you got a typo there.  The 12 milli-ohms is your load
impedance.  If you are modeling the battery as a fixed voltage source
with a series impedance, it is more like:

(12.65 - 5) / 400 = 19.13 milli-ohms

This assumes a nominal open-circuit battery voltage of 12.65V.
However, given the chemical processes in the battery, the speed at
which they occur, the temperature rise, etc - I'm not really sure if
this even accurately reflects the process.  I would guess that if one
were to plot impedance vs current drawn, that it would not be a
straight line.

Irregardless, it is still a very, very low number!!


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Battery Questions
Date: Mon, 19 Mar 2007 18:09:23 -0400
Message-ID: <>

On Mon, 19 Mar 2007 21:43:18 GMT, GaryO < @ . > wrote:

>P.S.  I just noticed "golf-cart" battery, so...
>(6.33 - 5) / 400 = 3.3 milli-ohms!!!
>a tiny...tiny... number  :-)

Right.  Sorry about that.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Help with Battery dieing in storage
Date: Mon, 26 Mar 2007 19:47:16 -0400
Message-ID: <>

On 26 Mar 2007 09:43:50 -0700, "ULB" <>

>Hi all,
>I only take my 30ft class c out a few times a year, when its not
>running down the road I have it in storage where the is no power.  It
>is not in an enclosed storage area so the sun hits it.
>Therein lies my problem, when I go to start it, the battery is way
>dead, sometimes even jumping won't get it going.
>Any ideas on if a slow solar powered trickle charge would help?  Do
>they even work?  Or other ideas?  Its quite a pita to pull the battery
>and come home and charge it, not too mention is probably killing the
>battery to boot.

Yep, they work, at least the larger ones do.  At least a half amp
capacity is required in my experience.

I currently have a solar panel on my mom's van which gets driven
almost never.  I have smaller panels (100 ma) in each vehicle that
keeps my portable booster packs charged.

A 500 ma panel will probably span half the dashboard.  The little 100
ma panels are about the size of a notebook.  Probably not adequate for
a full size battery.

If your MH is new enough to have a fuel injected engine then there
will be a constant drain of up to 500 ma (typ 50-100ma) on the battery
even with everything off.  This is to maintain the memory in the PCM,
the radio and other electronic modules.  This is the reason you'll
need the larger panel.

The alternative is to disconnect the battery when in storage.  I like
those battery posts with the green knob that is turned to disconnect
the battery.  Sold most everywhere for about $10.  The engine may run
rough for a bit until the PCM re-learns the tuning trim but that's no
big deal.

With the battery disconnected a small panel directly connected will
probably be fine.


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