Patent ID: 8299760

Claim:
A battery charger comprising: a circuit board including terminal portions that are provided to be exposed to the outside from an insertion portion, in which a secondary battery to be charged is inserted, and electrically connected to the secondary battery; a power circuit portion that obtains a voltage from an external power source and supplies a charging current to the secondary battery; a temperature detection unit that detects a battery temperature of the secondary battery; a charging control switch that turns on/off the charging current; and a controller that controls the power circuit portion or the charging control switch based on a voltage and a current of the power circuit portion and the battery temperature of the secondary battery, which are all mounted to a circuit board, wherein the temperature detection unit is provided in a part of the circuit board opposed to the insertion portion at a position spaced by a distance apart from each of a plurality of electronic components constituting the power circuit portion and the controller, the distance being equal to or larger than a predetermined distance which is set based on a heat generation temperature of each of the electronic components.