Battery sizing is a study function to determine the number of cells and cell size of the battery for a designated duty cycle. The number of cells is determined to satisfy the maximum system voltage during the battery charging period and minimum system voltage during battery discharging period. The number of cells/string is determined to provide sufficient power to the load cycle considering the minimum system voltage and minimum operating temperature. It also considered different factors that affect the battery performance, such as design margin, aging compensation, initial capacity, etc.