To protect a battery against overcharging or prevent reduction in the capacity of a lithium-ion battery, and prevent variations in cell voltages of the individual lithium-ion batteries during charging.
A charging power supply unit 4 for charging lithium-ion batteries 1 supplies a charging path for lithium-ion batteries 1 with a charging current of an arbitrary value that does not depend on a fluctuation in load. The lithium-ion batteries 1 are connected to or disconnected from a load device 3 by a switch 6. The full charging voltage of each single cell is detected with voltage regulation circuits 5 connected with each of the single cells of the multiple lithium-ion batteries connected in series, and a charging current is caused to make bypassing. Thus, variations in charging voltages of the individual lithium-ion batteries 1 during charging is thereby regulated.
MATSUSHIMA TOSHIO
Tadashi Takahashi
Takashi Watanabe
Masakazu Aoyama
Suzuki Mitsuyoshi
Kazuya Nishi
Yasuhiko Murayama