From: John De Armond
Subject: Re: Generator Information
Date: Fri, 24 Sep 1999 14:33:08 EDT
Newsgroups: rec.outdoors.rv-travel

Raveler wrote:
> 
> will@epix.net wrote:
> >
> ...There is a good common sense article on this website about generators
> right now...
>         http://www.rvtimes.com
> If the generator is for the sole purpose of charging house batteries,
> you might try a solar panel. Quiet, efficient, can be used anywhere.
> 

Pretty rough to charge the old batteries with the solar cells when
the clouds come.  Not to mention the cost.

I'd like to comment on this article.  I've owned the Honda EX350
practically since it came out.  We use it at craft shows to light my
wife's stained glass lamps when the shows try to rape us on power
hookup prices.  It stays in the trunk of my car otherwise to make
sure I never need a jump.  And it goes with us in the RV for when we
just need to run a fan or something outside and don't want to run
the big genset.

This is a gorgeous little unit.  It contains a 2 stroke
weed-whacker-type engine, a small car-style 3 phase alternator and
rectifier and a 300 watt inverter to make the 60 cycles.  It is only
a little larger than a lunch pail and weighs little.  Because the
generator does not have to run at a synchronous speed to make the 60
hz, the generator can be throttled according to the load.  The
article at RVtimes was misleading about this unit, obviously because
the author only read the spec sheet.  Because of the ability to
throttle the engine, the fuel consumption is pretty much
proportional to the load.  While the little tank runs dry in a few
hours at full load, at lower loads and for charging batteries, it
will run literally all day on a single fueling.

Aside from the size and weight, the other wonderful feature is the
noise, or lack thereof.  On low speed, I've had people stand within
a couple of feet of it and not realize it was running.  Many outdoor
crafts shows ban generators (coincidentally, they seem to be the
ones who charge exorbitant power hookup fees.) For these, I put the
generator in a large cardboard box lined with foam and equipped with
a few small holes for cooling air.  Even on high speed, the
generator is practically inaudible when standing beside the box.

Some would worry about the smell of the 2-stroke.  If the factory
oil mixing instructions are followed, that can be a consideration.  
But!  If you use a good synthetic oil (I think Honda sells the BEST
2-stroke oil. Period), the mixing ratio can be increased to 80:1 or
more.  I personally run 100:1.  All the bearings are either needle
or ball which needs only a mere whisp of oil.  The cylinder is
chrome plated so it needs very little oil too.  This produces no
smoke except during warmup and the Honda oil's smell is neutral to
pleasant.  Some might question using oil this lean but I've owned my
unit for about 8 years and it's still running like the day it was
new.

The battery charging feature is kinda weak.  It is rated at 8 amps
or some such but it won't do it.  I carry a small 10 amp battery
charger when I anticipate needing to charge a battery.

One other little note.  The 60 hz output is a square wave.  Square
waves contain lots of harmonics and the peak voltage is less than an
equivalent RMS value sine wave.  This has some important
consequences.

*	The sharp, harmonics-rich edges of the square waves will make
audio equipment buzz unless very well designed.  Most boom boxes do
NOT fall into this catagory!  That was a great disappointment to me.

*	Some fluorescent lights and every HID (mercury vapor, metal
halide) light I've ever tested will not work.  They need the higher
peak voltage of the sine wave to ignite properly.  HID lights are
particularly frustrating because they will start just fine but go
out after they get warm.

*	Some other devices, particularly older computers, that rely on the
sine wave peak to operate their power supplies will not work.  My
old Compaq 386LTE (may it rest in peace) fell in that catagory.  

*	The sharp edge of the square wave will make the iron in the
stators of cheap motors buzz.  This is most noticeable with a desk
fan on low speed.  Not terribly loud but noticeable.


Not directly applicable to generators but related since square waves
are involved.  Inverters come in 3 flavors:  Pure square wave
(cheapesst), pseudo sine wave (square wave with some steps in it)
and true sine waves (most expensive).  In the larger sizes (>500
watts), the square wave inverter is the most common because it is
the cheapest.  The Tripplite 1000 watt square wave inverter I have
in my catering van was half the price of a 1000 watt true sine wave
inverter.  What is important to understand is that with square wave
and pseudosine wave inverters, there are some devices that just flat
will not work.  The microwave oven is the most common example.

I orginally bought the inverter to power a microwave oven.  With the
van engine running, the inverter outputs 130 volts as indicated by
my true-RMS DVM.  Yet the microwave doesn't work.  It would power up
, the turntable would turn, the filament in the magnetron would
light but no power.  Why?  The magnetron power supply in the
microwave is designed to operate on the PEAK of the 60 hz sine
wave.  If one looks at the microwave output with a scope, one would
see that all the microwaves are generated during a very short period
at the peak of the sine wave.  The problem is, the peak value of a
square wave is much less than that of a sine with the same RMS
voltage.  The voltage never gets high enough to fire off the
magnetron.

Pseudo-sine wave inverters may or may not work, depending on the
design.  The important thing to realize that testing before buying
is a must.

John
John