To provide a practical method and device to determine the residual capacity of a secondary battery for determining an idling stop process with high reliability.
This arrangement includes a determination means 8 which, (a) presumes the residual capacity of the secondary battery 3 through the comparison of the measurement given by a voltmeter 7 with predetermined thresholds at a plurality of levels, (b) enters the inter-terminal voltage of the secondary battery 3 within a certain time of an engine restarted as a first inter-terminal voltage from the voltmeter 7, enters the inter-terminal voltage of the secondary battery 3 after an elapse of a first specified time from the engine restarted as a second inter-terminal voltage from the voltmeter 7, calculates a voltage difference by subtracting the second inter-terminal voltage from the first, and determines whether the first inter-terminal voltage is over a first specified voltage and the voltage difference is a second voltage value, and (c) the sensed temperature of a temperature sensor 6 lies between the predetermined upper limit and lower limit, and the arrangement further includes an idling stop processing means 10 which decides whether the idling stop is made on the basis of the total determination result.
IWAHANA FUMIKAZU
NAKAMURA HIDETO
KANO TETSUYA
FURUKAWA BATTERY CO LTD
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