Freezing batteries - not with LiFePO4
The lead acid battery will freeze when fully discharged. See this: The electrolyte of a fully charged lead-acid battery with density of 1.28 g/cm3 changes the structure to solid at -68°C. With density of 1.25 g/cm3 (slightly discharged battery), the electrolyte will freeze at -52°C. A half discharged battery (with density of 1.15 g/cm3) will freeze at -15°C. A fully discharged battery (density of 1.1 g/cm3) will freeze at -7°C. Completely depleted battery will freeze right bellow zero degrees Celsius.
The LiFePO4 battery is operational at low temperatures with no significant change in charging and discharging. There is no danger that LIFePO4 battery will “freeze” in a cold weather.