Alternator overcharging batteries
I have 4 AGM batteries in my rig with a total capacity of 440AH (actually 880AH @ 6V, but of course they are wired to get 12V). The data sheet for my Haze batteries species a bulk -> absorption cut...
Forum Discussion
full_mosey wrote:Gerald55 wrote:
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OK, the need for high amp recharges was news to me. Or is this basically another way of saying that AGMs do need equalization? ...
No. Equalization is a flooded(FLA) thing; meaning to use excess VOLTS to force electrolysis so that the stratified acid is re-stirred EQUALLY throughout the liquid.
Well, not anymore. When AGMs were just penetrating the market, the conventional wisdom was "don't equalize", but that's been changing. Today, several (most?) of the top-line AGM manufactures recommend some type of equalization. Often it seems to be a "vent-less" type of equalization - i.e., not gassing enough to pop the vents on the AGM, so no electrolyte is lost.
In any case, it's clear that some of the benefits of equalizing carries over from flooded LA to VRSLA AGM as well.
As to 'the need' for high Amp charging, there is partial truth to that. The lowest actual mfgrs spec I have seen is to limit Amps to 30% of the 20hr rating. The highest I have seen is unlimited Amps. Some of this is lawyer talk and some is marketing talk.
OK, but that only seems to support the idea that charging too fast can be a problem, not that charging too slow can be?
AGMs do benefit from temp comp chargers. These chargers limit Volts by reading the battery temperature via a probe. IMHO, the purpose is to maximize Amps while at the same time keeping Volts below electrolysis. Allowing electrolysis is simply a waste of energy in an AGM and results in slower charging.
Yes, I use a temperature probe to enable temperature aware charging in my setup.
