Hitachi, Ltd.

Junichi Miyata

Jun Kitahara

Kenichi Saitou

Masato Ishii

Hitoshi Takeoka

A battery assembly unit and a method of charging the same for applying constant current/constant voltage charging to a battery assembly in which a plurality of battery cell groups each having battery cells each being rechargeable and increasable in electromotive force as charging proceeds are connected in series. There are provided a reference charging voltage circuit for generating charging reference voltages serving as voltages referenced to electromotive force levels of the individual battery cell groups on the basis of charging voltage applied across the battery assembly and changeable with time, and comparison circuits each adapted to compare an electromotive force level across each of the plurality of battery cell groups connected in series with the charging reference voltage. Further, bypass circuits are provided each of which connected in parallel across each of the plurality of battery cell groups connected in series and when an electromotive force of a battery cell group exceeds the charging reference voltage, bypasses the charging current by an amount corresponding to a difference.

Growing community of inventors

Chiba, Japan

Junichi Miyata