Yazaki Corporation

Brendan O'Toole

Youichi Arai

Tsutomu Saigo

Yoshihide Takada

Kenichi Shimoyama

Ryo Kumagai

A voltage sensor detects a terminal voltage of a battery connected to a load and a current sensor detects a current flowing through the load. A voltage-current changing tendency calculation unit reads a detected voltage and a detected current detected by the voltage sensor and the current sensor and outputs, every predetermined period of time, plural data of the detected voltage and the corresponding detected current as dispersed data. A voltage-current approximating line calculation unit inputs the dispersed data and determines, based on the dispersed data, a voltage-current approximating linear function each time the predetermined period of time. A battery remaining capacity calculation unit determines, each time the voltage-current approximating linear function is determined, a remaining capacity of the battery based on the voltage-current approximating linear function. Particularly the voltage-current approximating line calculation unit determines the voltage-current approximating linear function by applying a method of least squares to the plural data of the voltage and the corresponding current of the dispersed data.

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Co. Kerry, Ireland

Brendan O'Toole