Makita Corporation

Hideki Watanable

Toshio Matsumoto

A battery charger includes a circuit for monitoring a battery voltage during supply of a charging current to a battery, and a circuit for stopping the supply of the charging current when the battery voltage is decreased by a predetermined value after the battery voltage has reached its maximum value. A first predetermined value is adopted as the predetermined value when an increasing tendency of the battery voltage is detected after a predetermined time has elapsed from starting of the charging operation. A second predetermined value is adopted as the predetermined value until the increase tendency of the battery voltage is monitored after the predetermined time has elapsed from starting of the charging operation. The absolute value of the first predetermined value is determined to be smaller than that of the second predetermined value. The predetermined time is determined to be longer than the period of duration of temporary abrupt variation in the battery voltage which may be produced at the beginning of the charging operation of the over-discharged battery.

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Anjo, Japan

Hideki Watanable