Patent ID: 7573233

Claim:
A battery system, comprising: a battery pack having a plurality parallel groups connected in series, each parallel group including a plurality of power sources connected in parallel, each power source including a battery; and electronics configured to repeatedly charge and discharge the battery pack according to a charging protocol configured such that the voltage of any one battery in the battery pack does not exceed its maximum operational voltage after failure of a battery in the battery pack, and wherein the charging protocol includes charging the battery pack to a charged pack voltage that is less than a maximum operational voltage of the battery pack, the charging protocol includes discharging the battery pack such that the battery pack discharge is stopped before the battery pack voltage falls to a discharged pack voltage, the charged pack voltage being the same before and after the failure of the battery, the discharged pack voltage being the same before and after the failure of the battery, and the charged pack voltage and the discharged pack voltage are such that discharging the battery pack from the charged pack voltage to the discharged pack voltage before failure of the battery results in each battery providing a capacity that is less than or equal to C m (M−1)/(M+1), where M is the number of power sources in each parallel group and C m is the maximum operational capacity of the battery.