Makita Corporation

Fuji Electric Co., Ltd.

Okada Electric Co, Ltd.

Hideki Watanabe

Toshio Matsumoto

Tatsuki Mori

Masatoshi Sugiura

Toshiyasu Kasuya

Masami Furuta

Takao Iwatsuki

Hideiki Niwa

A battery charging system is disclosed for charging two different types of battery packs, a known three terminal type including batteries and a thermostat switch, and a newer four terminal type further including a thermistor for sensing battery temperature. A charging control circuit stops charging current to the battery pack when a contact of the thermostat switch is open or when the thermistor detects a temperature above a predetermined temperature. If either the thermostat switch or the thermistor fail to properly operate, charging current to the battery pack is stopped securely to avoid damaging batteries.

Battery charger detecting full charge of batteries using a thermostat

A battery charger includes a circuit for detecting battery voltage (V1) appeared when a predetermined time (T1) has elapsed after starting a charging operation. The determination as to whether the battery has been fully charged is performed after the battery voltage has reached the sum of a predetermined potential difference (dVS) and the battery voltage (V1).

Battery charger which accounts for initial surge in battery voltage and

A battery charger includes a transformer having a primary coil and a secondary coil, a switch for duty control of a current flowing through the primary coil of the transformer, a detector for detecting a value of a current flowing through the secondary coil of the transformer, and a secondary controller for receiving the detected value from the detector and for outputting a charge control signal. The pulse of the charge control signal is modulated in accordance with the detected value by the detector. The battery charger further includes a light emitter controlled by the charge control signal for flickering, a phototransistor turning on and off according to the flickering of the light emitter, and a primary controller for converting the ratio of the time during on of the phototransistor to the time during off of the phototransistor into an analog value, and for outputting to the switch a pulse signal which is modulated to have a duty cycle corresponding to the analog value so as to control a duty cycle of the switch.

Battery charger with charging current controller

Growing community of inventors

Anjo, Japan

Hideki Watanabe