Nawaz is the best person to answer this, but: As I understand, warmer electrolyte is more chemically active than cold one, (as for about any chemical reaction). Depleted layers of acid immediately near active material of the plates mixes up with the rest of free acid faster so it provides more current, meaning effective capacity appears more as well.
The same true for charge: "higher capacity" battery (i.e. your regular battery at higher temperature) requires proportionally higher current to replenish this capacity. Say cold optima is 40 Ah and hot one is 60 Ah. (numbers are for illustration only). This means hot one will give out about 1.5x current and be discharged to the same DOD during the same time. Obviously, to charge back 60 Ah battery you need 1.5x current vs charging 40 Ah one. Chuck Hursch wrote: > > Hello All, > > I'm not understanding why a warmer (Pb-acid) battery takes more > current to produce a given voltage under charge than a cooler > battery. Seems that lead-acid batteries are supposed to be more > efficient (less internal resistance) when warm than cold. So I > would expect the opposite of what occurs. Any explanation? > > Thanks, > Chuck Hursch > Larkspur, CA > www.geocities.com/nbeaa > 1979
