I always chuckle when I read “Don’t charge a frozen battery”. Yeah, that’s true, but don’t let it get discharged/frozen in the first place.
One of my banks was in the water heater closet but it got kicked out. No good answer right now to the ambient storage issue except keep plenty of gas for the generators esp. in the winter. Charging the batteries will warm them but it’s hard to get enough current to do that with a bank.
It was scary the other cold morning when our power went off for just three hours or so. Stayed in bed hoping power would come back on and just when I reluctantly got up and started to get dressed, it came on. We can’t afford an automatic standby system but I was all ready in my mind what to hook up where. We have a propane fireplace for the living room so heat at least in that part of the house for a week or so would not be a problem.
That's damn hard on the battery. You can get small heat strips that will keep the batteries warm. Sure it uses power, and they rate them for 120VAC... They are resistors. Measure the resistance, do the E=I*R and P=I*E math and wire 'em for 12 or 24 volts, whatever your bank is running. Beats replacing batteries every 5 years.
Hell, even cooks can do that basic math.
Some cooks. On good days. ;)
That solar panel bank and battery bank was literally all I had for electric power for almost 2 years. I certainly didn't quit freeping when it was -18F outside.
/johnny