A method (900) of reducing variation of an energy storage capacity of a battery across its cycle life is disclosed. The method can include the step (901) of monitoring one or more voltages of one or more cells of a battery for a predetermined discharge usage time. Where a profile of the one or more voltages during the predetermined discharge usage time meets a predefined usage criterion, the method can include the step (907) of increasing a discharge voltage limit of the one or more cells. An energy management circuit (614) can be configured with a control circuit (702) operable to increase the discharge limit and to limit discharge of the cells when the discharge limit is reached.