Robust battery [RE-wrenches]

[Brad Bassett]

Back at a previous place I worked, we installed a good number of 
Absolyte battery banks. A few more observations:

They lasted about 7-8 years in solar applications, with some hybrid 
input.

Although their literature says they are freeze tolerant, don't believe 
it. Even following their instructions I've never seen one recover from 
being frozen. Also it can be dangerous to charge a frozen battery.

Although their literature says they are tolerant of extended periods 
with a partial state of charge, don't believe it. If they are not fully 
recharged just like other lead acid batteries they will lose capacity 
and their positive plates grow at a prodigious rate. I've seen broken 
cell casings from plate growth. I tried to get my bank to last through a 
northwest winter without generator backup, and the battery had less than 
25% capacity the next spring. I was not able to recover any more. I then 
got into a cycle where trying to equalize the battery to recover 
capacity just made the plate growth worse.

Voltage set point is very specific in relation to daily depth of 
discharge to maintain the warranty, but at least they recognize that a 
higher voltage is desireable when cycling is deeper. Still, in the 
telecom systems we'd set the regulation point at 2.46v /cell for on/off 
controllers (14.8 for 12 nom). I think they like the higher voltage to 
fully recharge, but it may void the warranty to charge at higher 
voltages than the recommendation. We never had a problem with electrlyte 
dryout that they are noted for, but I think that happens when they are 
in float service.

Sometimes you can remove the cells from their steel case to transport 
the battery into spots where vehicles can't get in, sometimes, depending 
on a number of factors like altitude, temperature, how rough you want to 
get, etc. The factory doesn't recommend it but are aware that it 
happens.

Absolytes are indeed good batteries for the reasons pointed out by Dan. 
I just thought I'd clarify a few points in case someone thought they 
were miracle batteries. Guess I'll go out and water my L-16's now.

Brad Bassett
Alternative Energy Eng.
Olympia, WA
brad at alt-energy.com

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