Honda Motor Co., Ltd.

The Furukawa Electric Co., Ltd.

Furukawa Automotive Systems Inc.

Fukuda Kazumi

Etsuzo Sato

Hideaki Ishihara

Naoki Ishiyone

A current detecting unit (current sensor) detecting a current value of a current flowing in a secondary battery; an extreme value detecting unit (CPU) detecting a first extreme value of a current after an inrush current flows from the secondary battery to a starter motor after electricity to the starter motor is turned on based on the current value; an inflection point detecting unit (CPU) detecting a first inflection point of the current after the inrush current flows based on a variation of the current value per a predetermined time; and a calculation unit (CPU) selecting the inflection point when timings when the extreme value and the inflection point are detected are separated for a predetermined time or more, and selecting either one of the extreme value or the inflection point in the other cases to set as a starting current, and calculating a starting voltage from the starting current, an internal resistance of the secondary battery, and a voltage before starting being a voltage of the secondary battery before the electricity to the starter motor is turned on, are included.

Growing community of inventors

Tokyo, Japan

Fukuda Kazumi