| 摘要 |
PROBLEM TO BE SOLVED: To detect an abnormality to restrict charge/discharge and thereby to protect a secondary battery by providing an abnormality detection accumulation means for accumulating abnormalities every time the charge voltage of the secondary battery exceeds a threshold value, an abnormal voltage detection means used in the case that the cumulative result exceeds a predetermined value, and an abnormality canceling means for reducing the cumulative result every time the charge voltage is set below the threshold value. SOLUTION: When it is determined that the value of a counter C2 reaches, for instance, a predetermined value 10 because a charge voltage VC continues to be a threshold value Vth or more to a certain extent, an abnormal high voltage of a battery cell is detected and thereby, a control circuit opens a switch to stop charging, Since a cumulative result is reduce every time the charge voltage of a secondary battery is set below the threshold value, the abnormality of the secondary battery is prevented from being erroneously detected by gradually accumulating the cumulative result over a long period. Even if the charge voltage temporarily returns below the threshold voltage Vth in the course of operation, the abnormality can be practically detected without being affected by noise or the like, provided that the charge voltage is equal to or above Vth.
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