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From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Carl A.'s Westy
Date: Sat, 04 Nov 2006 14:32:09 -0500
Message-ID: <>

Correct, of course.  The problem is, there are many people giving
(regurgitating) advice who have no real experience.

One way to gauge what a battery will do under normal circumstances is
to abuse one under extraordinary circumstances.  In my high school
years I did just that for the purpose of making H2/O2 mix to fill
exploding balloons with.  Plumb all the caps together with aquarium
tubing and tees and route the mix to the balloon.

Even whacking the battery with the "100 amp boost" from the
roll-around garage charger which would eventually put the battery into
thermal runaway and actual boiling, it took better than an hour to
inflate a small 9" balloon.  I ended up with 4 batteries plumbed in
parallel, each fed with its own charger, to generate enough gas to
fill a balloon before the spectators got bored and left.

Even if one of THOSE batteries had been placed under a couch, there
would not have become an explosive mixture.  There is too much air
exchange even with a "sealed" compartment.  Plus the H2 quickly rises
to the top and escapes out cracks and holes.

Just to be sure my theory was correct, the first time I put a set of
batteries under the seat of my rig, I checked out the spaces with my
explosive gas monitor while heavily charging the pack.  As I expected,
absolutely nothing.  Meter never came off zero.

I moved the batteries inside on both my current rig and my mom's.
There are many benefits.  A biggie is that the batteries are no longer
exposed to weather extremes, at least while the rig is heated/air
conditioned, which in my case is all the time.

The batteries are no longer exposed to road crud which at a minimum
contributes to slow discharge via case leakage if not cleaned

Then, of course, they're right there handy for easy maintenance.

Mainly as an indicator to tell me if acid fumes are escaping, I clad
the wood on the seat above the batteries with a sheet of aluminum.
Foil will do, though I use flashing metal.  If any acid escapes then
there will be discoloration and perhaps even a hole above each battery
vent.  So far all I've seen is a little discoloration, not enough to
call corrosion.  This is with the pack being managed by the
Intellipower/Charge Wizard.

AGMs are wonderful but are much less tolerant of abuse than wet
batteries.  One or two abuses with a non-smart charger can kill one.
Like most people who fool with electric vehicles, I had to learn that
one the hard way.  Fortunately, only killing a 36 volt pack.

I use 'em on all my electric vehicles.  One pack is going on 5 years
old and has lost no range (range is everything to an EV).  However, it
has a smart charger that cost about as much as one of the batteries
and that is designed for this specific battery chemistry.  The
traction controller has a hard low voltage cutoff that stops motion
when the batteries reach the mfr's designated discharge point.  IOW,
they're babied.

Slap an AGM in an RV, charge it with the OEM dumb charger and use it
until the lights get dim and get ready to limber up that wallet fairly
often.  Wet cells are far more tolerant of this kind of abuse and are
far cheaper to replace.

One area where AGMs really shine is in current production.  I've taken
money from unsuspecting bettors more than once by cranking my medium
duty truck's diesel engine using a single 17ah Hawker AGM scooter
battery.  Of course, I knew that this battery is rated for 1500 amps
into a short and 1000 amps @ 10 volts.

If one needs to run heavy inverter loads very often, say, the
microwave, toaster, coffee pot, etc., then AGMs quite superior.  The
voltage hangs right in there under load until the battery is almost

As with many other things in life, one needs to sit down and analyze
his usage before selecting the battery system.  For typical casual
camping, wet batteries work very well.  If you're a hard-core
boondocker with limited space and are willing to spend the money both
on the batteries and the necessary charging and monitoring equipment
then AGMs can't be beat.


On Sat, 04 Nov 2006 03:31:16 GMT, (Harry
Chickpea) wrote:

>GBinNC <> wrote:
>>Let me put it this way -- I will never have any other kind of house
>>battery than an AGM. (I have one Group 24. That's all the space I have
>>for house batteries, but that's also all I need.)
>The ONLY (repeat *ONLY*) time to be concerned about lead acid
>batteries is during an equalizing charge, when they DO give off acid
>fumes and stand a chance of self destructing.
>AGMs are fine, nothing against them.  Just don't have a problem with
>other options.

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