Larry wrote in
:

A pipe dream of battery chemistry. 375AH requires 5 hours (from 50%
discharge, not zero) at 38A, not 115. Batteries charge at 10% of AH
rating, not 30, if you want to convert the electrolyte, giving it time
for circulation.

I note that my batteries (2 Caterpillar 153-5720 8Ds) are speced at a max
charging rate of 5% of their CCA, which is 1500 A. That works out to 75 A.
Each of the batteries have a rating of 210 AH, which based upon Larry's
math, would be 21 Amps, or 42A for both of them.

That said, this whole discussion doesn't make a lot of sense to me. I
watch my 3 stage regulator charging rates, and it spends very little time
charging at full throttle. When initially turned on, the charger goes into
bulk charging mode and attempts to get the charging voltage up to the bulk
charging voltage. This voltage depends upon the battery temperature and I
have a thermocouple which sends the battery temperature back to the
charger. I've specified a temperature coefficient in the charger (which is
specified in mV/degree C) and as the battery gets warmer, the bulk charging
voltage drops.

Anyhow, I try not to let my batteries get below 12.5V. When I charge the
batteries I see my charger outputting at its maximum charge rate (110A) for
about 15 minutes and then it typically has reached the bulk charging
voltage. Then the charging rate drops as it maintains that voltage. My
typical charging cycle runs for about 1 hour, and at the end of that hour
I'm only outputting about 20A. It will take several more hours for the
rate to drop to 0.

Thus, this talk about charging at some rediculously high rate for X hours
doesn't seem to have much to do with real charging systems

-- GEoff