Patent ID: 7932694

Claim:
A battery charger comprising: a body that is connectable to a battery pack containing a battery to charge the battery; a first connecting member having one end connectable to a first power supply and another end connectable to the body; a second connecting member having one end connectable to a second power supply and another end connectable to the body; wherein the body comprises: a first voltage detector that detects a voltage generated by the first power supply; a second voltage detector that detects a voltage generated by the second power supply; and a control unit that selectively uses one of the first and second power supplies as a power source of the body in response to outputs from the first and second voltage detectors; a first switching element; a first switching controller connected to the first switching element for controlling the first switching element; a second switching element; a second switching controller connected to the second switching element for controlling the second switching element; and a transformer having a first primary winding to which the first power supply is connectable via the first switching element, a second primary winding to which the second power supply is connectable via the second switching element, and a secondary winding to which the battery pack is connected.