Patent ID: 7126312

Claim:
A method of operating a battery system having a charging and balancing cycle with a beginning-of-charge (BOC) time, the system having a plurality of cells, said method comprising the steps of: charging the plurality of cells staffing at the beginning-of charge (BOC) time; balancing at least a first one of the plurality of cells during said charging step based on a predicted balancing parameter determined for the at least first cell; determining, for each one of the cells, a respective required charge amount indicative of an amount of charge required to reach an end-of-charge (EOC) state; calculating a maximum required charge from the required charge amounts determined for the cells; determining a difference-in-charge for each cell representative of the difference between the maximum required charge and the respective required charge amount determined for each cell; determining a respective time-to-balance for each cell based on the corresponding difference-in-charge to thereby define the predicted balancing parameter; said balancing step is performed for the determined time-to-balance associated with the at least first one cell; said balancing step is performed for additional cells from the group of cells having a positive time-to-balance, said balancing step enduring for each additional cell for a time corresponding to the respective time-to-balance; and said balancing step starts at the beginning-of-charge (BOC) time for a subset of cells less than all of the cells in the group having a positive time-to-balance.