The Amp hour (Ah) capacity for LiFePO4 batteries is normally around 100% at 15 degrees C. It is slightly higher than 100% at 25 deg C and up to 10% - 20% higher capacity at 40 degrees C. However, the capacity drops to about 90% at 0 degrees C and 80% at minus 10 degrees C. LFP batteries can be used below zero degrees C but they cannot be charged sub-zero. Battery warmers are used if charging at a sub-zero temperature is required. Specialised sub-zero LFP batteries with built-in warmers are also available. The State Of Charge (SOC) should not go under 15% below minus 10 degrees C. The built-in Battery Management System (BMS) ensures the battery is protected.