The common RV battery for cold weather is a LiFePO4 battery. These can be used down to -20°C (-4°F), but you must not charge them below freezing, it will destro

The common RV battery for cold weather is a LiFePO4 battery. These can be used down to -20°C (-4°F), but you must not charge them below freezing, it will destroy the electrodes. The batteries integrate a heater which absorbs charging energy until the battery is safely warm enough to accept the charge, then charges normally. In an EV this would be handled when charging by running a heater until it is a safe to accept charge. When driving, any time the battery becomes too cold you would divert regenerative braking energy into heating the batteries instead.