US Patent 8378624 Battery charger

An energy-efficient and compact multi-port battery charger. The battery charger includes, among other things, a power supply module, a battery charger control module or controller, a power switching module, one or more power control safety modules, a plurality of battery charger switches, and a plurality of indicators. The controller, the power switching module, the power control safety modules, and the battery charger switches work in conjunction with each other to control the operation of the battery charger. The controller is configured to execute a charging control process which detects the insertion of a battery pack into a charging port, selects a charging port for charging, controls the power output from the power switching module, and controls the illumination or display of the indicators. The power switching module uses control signals from the controller to switch the power received from the power supply module such that a charging current is applied to a single charging port. Each of the power control safety modules includes a power control safety circuit that is configured to prevent the charging current and/or the charging voltage from damaging the battery charger or battery pack during a malfunction.