| 摘要 |
A battery pack has a charge and discharge count measuring part (131) configured to measure the number of times of charges and discharges of a secondary battery based on the summed value of the charge current for the secondary battery, and a decay rate output part (132) configured to compute a decay rate that indicates a degree of decay of the secondary battery based on the number of times of charges and discharges measured by the charge and discharge count measuring part (131) and to output it to a device being a discharge load. For example, the charge and discharge count measuring part (131) repeatedly sums the detected values of the charge current to a predetermined threshold, and counts up the number of times of charges and discharges every time when the summed value reaches the threshold. Accordingly, even though charges and discharges are repeated at finer steps in a relatively narrow voltage range, the number of times of charges and discharges can be counted accurately, and the computing accuracy of the decay rate is improved. In the battery pack in which the secondary battery is accommodated, parameters for detecting the remaining amount of the battery are detected more accurately.
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