Patent ID: 7777451

Claim:
A method for charging a plurality of rechargeable battery series-parallel set assemblies electrically connected in series with a battery charger, each battery series-parallel set assembly comprising a plurality of rechargeable batteries, each having a positive terminal and a negative terminal electrically connected in series to form a series battery set, and a plurality of said series battery sets electrically connected in parallel to form a battery series-parallel set, and means for self-discharging the battery series-parallel set, said means being electrically connected in parallel with said battery series-parallel set, said method comprising continually determining a voltage across each battery series-parallel set assembly, then if the voltage is a preset value, self-discharge the battery series-parallel set until the voltage is equal to the preset voltage, then further self-discharge the battery series-parallel set for a period of time (t), wherein time (t) provides a discharge of the battery series-parallel set charge corresponding to a preset percentage of the battery series-parallel set's charge capacity.