To provide a battery charger for a vehicle driven by an internal combustion engine capable of preventing the overcharging of batteries at the time of driving the engine at high revolutions and controlling the temperature rise of power generator coils.
A switching element 9u is inserted between the output terminal of one phase of three-phase power generator coils Lu to Lw and its corresponding input terminal of a rectifier circuit comprising diodes Du to Dw and Dx to Dz. A switch controlling circuit 10 for the on-off control of the switching element is provided in such a way that, when the number of revolutions of the engine is less than the pre-set one and the terminal voltage of a battery 3 is lower than the lower limit value of a permissible range, the switching element 9u is held in the closed state, and it is opened when the number of revolutions of the engine exceeds the pre-set one and the terminal voltage of the battery 3 does the lower limit value of the permissible range.
TAKADA MITSUO
SHOJI SHIN
KIMURA MASAMITSU
SERIZAWA YOSHIMASA
