Patent ID: 8802252

Claim:
A method for extending a useful life of a rechargeable energy storage unit having a plurality of storage cells, comprising: measuring a temperature of each of the storage cells, wherein each of the storage cells is provided with a respective temperature monitor; determining whether the measured temperatures from the respective temperature monitors exceed a reference value for the temperature of each respective storage cell; and if the temperature of at least one of the plurality storage cells exceeds its respective reference value, determining which storage cell of the at least one of the plurality of storage cells which exceeds its temperature reference value has the highest temperature of all of the plurality of storage cells; partially discharging only the storage cell having the highest temperature of all of the plurality of storage cells to reduce the voltage of the storage cell having the highest temperature; and increasing voltages of the remaining storage cells by a voltage that is determined by dividing the amount of voltage decrease of the storage cell with the highest temperature by (n−1), where n is the number of storage cells in the plurality of storage cells.