Charger is to recharge the battery device, generally two-stage charging mode and three-stage mode two. Two-stage charging mode: the first constant voltage charging, charging current with the battery voltage rise gradually reduced, and other battery power to a certain extent, the battery voltage will rise to the charger set value, this time into trickle charge. Three-stage charging mode: the beginning of charging, the first constant current charging, and quickly add energy to the battery; such as battery voltage rise to constant voltage charging, this time the battery energy slowly added, the battery voltage continues to rise; to charge the charge termination voltage Value, to trickle charge to maintain the battery and supply the battery self-discharge current.