BATTERY PACK 36 V, 5.2 AH, LI-POWER EXTREME, ?AIR COOLED?USER BENEFITS:Ultra M technology: Intelligent battery management for long-lasting battery packs with a 3 year guaranteePatented ?AIR COOLED? charging technologyPermanent Electronic Single Cell Protection (ESCP) when charging, for particularly long life.Processor-controlled charge and discharge managementCapacity display with almost no self-dischargeCapacity display with almost no self-discharge