Patent ID: 8310203
Filing Date: 2012-11-13
Classification: H02J

Abstract:
1. A battery balancing method for a battery pack, in which the battery pack has a plurality of rechargeable battery cells, comprising the steps of: (a) starting to charge the battery pack; (b) categorizing the battery cells into a first subgroup and a second subgroup, wherein each battery cell of the first subgroup has a corresponding over voltage count number greater than or equal to 1, and wherein each battery cell of the second subgroup has a corresponding over voltage count number equal to 0, the over voltage count numbers indicating how many times the corresponding battery cell has ever reached an over voltage protection point; (c) detecting a minimum voltage among the battery cells of the second subgroup; (d) when a voltage of a battery cell of the first subgroup is higher than the minimum voltage, decreasing the voltage of the battery cell to a buck voltage lower than the minimum voltage, wherein the buck voltage of the battery cell is based on the over voltage count number of the battery cell, a voltage constant of the battery cell, and the minimum voltage; (e) equalizing the voltages of the battery cells of the second subgroup based on the minimum voltage and equalizing the voltages of the battery cells of the first subgroup based on the buck voltages; and (f) discontinuing charging.