Charged batteries can tolerate quite a bit of cold, although the performance suffers in that you will get more of a voltage drop for a given amp draw, and the maximum amps the bank can put out will be reduced. I have an electric car, and when I got it, the lead acid batteries in it were all busted from freezing. Dead batteries are less acidic and the freezing point of the electrolyte is higher although I don't have the specific info on that. In a working system you will probably never let you batteries get that flat though so it should not be that much of an issue for you I would think. Conversely I recall that batteries in the tropics don't last as long because of the higher temperatures. Typically as a rule of thumb for most chemical reactions, the rates about double for each time the temperature is increased by about 10 degrees Celsius, so I would reckon that a battery stored and used at an average temperature which is about 10 degrees Celsius, or 18 degrees Fahrenheit warmer would last only about half as long, but that's just an approximation of course. Rich