[Coco] Waaaaaaaayyyyyy of topic

[Gene Heskett]

Hi all;

Is there anyone here that knows ALL about the care & feeding of lead-acid 
batteries? I have considerable experience with them in car & truck sizes, 
but the one in my 20kw standy generator would be adequate for a 2CV in 
warm weather only.

I appears that Generac has equipt their 20kw nat gas standby with a 
trickle charger that IMO is way too beefy, holding it to 13.88 or .89 
volts.  That is sufficient to make any battery gas and use up its water 
way before it should.  Ideally, and in my experience if the holding charge 
is correct, no gassing occurs, and they can go 6 to 10 years w/o a drink 
of water.  I once made a switchmode voltage regulator for a car battery 
that when adjusted, worked well.  It could start a tired 63 tin indian 
wagon at -37F just like it was a warm spring day, and it, the alternator 
and battery were used on the next 4 cars I owned over a period of 8 or 9  
years, and I never had to add water to that battery, despite the fact that 
a startup on a cold morning would bang it up to about 15.9 volts at nearly 
100 amps from that HD alternator, but it faded to cool spring settings in 
about a minute, then to warm summer settings as the engine compartment 
warmed up, so the overcharge out-gassing was very close to zilch.

I applied that same theory to a pair of 220AH 12 volters used as 24 volts 
by switching them into series to start the 150kw Cummins 335 powered 
standby generator at KXNE-TV in NE, and determined that a 1000 ohm series 
R from the line powered charger was way too low, and while I don't recall 
the actual resistor I used to limit it maintenance charge, I do recall 
that I was down to around 7 milliamps for the 2 batteries in parallel to 
keep them from outgassing while still maintaining around 13.65 volts for 
long periods of time.  When I went down the road to the next job, those 
batteries were then 7 years old and I had added water once, about 2 weeks 
after I discovered that charger was burning them up.  And likely burn up 
the 3 year old batteries I had to replace.  And they were still turning 
that Cummins hard enough it fired on the first cylinder to pass tdc, so 
start time to 1800 rpm and back on the air was less than 4 seconds from a 
power failure.

Now this Generac has gassed about 10 to 12 oz per cell out of an 81 AH, 
575 cold cranking amps battery in something under a year.  Not enough to 
expose plates (that FWIW, is very bad for the batteries health & well 
being), but enough to trigger a check battery warming on the control 
panel.  So I filled it with distilled, and reset the alarm.  And logged 
it.

I guess my question is how do I get a suitable LART to convince Generac 
their charger circuitry is junk?

Cheers, Gene Heskett
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