Shorai LFM Lithium-iron Battery w/BMS, LFM14A2-BS12, 4.0Ah 13.2V, 52.8WHr, "A" polarity, Case Type 2. Shorai Batteries require a charging system output of 13.1 Volts or higher at idle, and must not exceed 15.2 volts at maximum output. Due to transport regulations, all batteries are shipped at 30% SOC (State of charge). Please fully charge the battery before use.