01-20-2016, 10:40 AM
(01-20-2016, 07:21 AM)The ferret_imp Wrote: Batteries at rest lose charge whether connected or not .. something about positive ions and all that...otherwise you wouldn't need a generator or alternator or trickle charger to keep it up. I've heard as much as 1% per day but that may have been old technology lead acid filled batts. They do not store an infinite amount of power for an infinite amount of time. Even when being charged daily they eventually will no longer hold a charge. Nature of the beast.
That's about right for a flooded cell battery. Actual discharge rates also vary with temperature (hotter temps, higher discharge). You're correct that newer technologies do better. Sealed AGM batteries self discharge rate is about half of the flooded cell rate. Lithium batteries are pretty good in this respect, discharging at only 2-3% per month.