Originally Posted by Ozark Bob
This is something I have offered up before. https://www.solacity.com/how-to-keep...tteries-happy/
This is part of it.
Storing Lithium-Ion Batteries
The very low self-discharge rate makes it easy to store LFP batteries, even for longer periods. It is no problem to put a lithium-ion battery away for a year, just make sure there is some charge in it before placing it in storage. Something between 50% – 60% is ideal, that will give the battery a very long time before self-discharge brings the Voltage close to the danger point.
Storing batteries below freezing is fine, even at very low temperatures such as -40 Centigrade (that is the same in Fahrenheit), or even less! The electrolyte in LiFePO4 cells does not contain any water, so even when it freezes (which happens around -40 Centigrade, depending on the particular formulation) it does not expand, and does not damage the cells. Just let the battery warm up a bit before you start discharging it again, which is OK at -20 Centigrade and above. You will see an apparent loss of capacity when discharging at below-freezing temperatures that reverses when the battery gets above freezing, and there is a slightly accelerated effect on aging. Storing them at low temperatures is certainly much better than storage at high temperatures: Calendar aging slows down dramatically at low temperatures. Try to avoid storing them at 45 Centigrade and above, and try to avoid storing them completely full if possible (or nearly empty).
If you need to store batteries for longer periods, be sure to simply disconnect all wires from them. That way there can not be any stray loads that slowly discharge the batteries.
That's what I originally thought, Bob, and though I have no real background in this stuff, it made sense to me. But I've definitely been focusing on LiFePO4 batteries (specifically 100Ah 12V Deep Cycle LiFePO4 batteries for marine use), and the numbers I stated above are definitely what the manufacturers have to say about minimum storage temperatures, not minimum discharging or charging temperatures.
From Battle Born:
The storage temperature range is -10°F to 140°F (-23°C to 60°C)...
Battle Born Batteries... won’t accept a charge once the internal cell temperature drops to 24°F. At this point they will continue to discharge even down to -4°F.
Discharge Temperature -4 to 140 ºF (-20 to 60 ºC)
Charge Temperature* -4 to 113 ºF (-20 to 45 ºC)
Storage Temperature 23 to 95 ºF (-5 to 35 ºC)
So I'm hoping you and other folks here can help me work through the questions I asked.