Abstract: A rechargeable battery having a user-selected charge capacity whereby a user of the battery can select the voltage at which the battery is charged, and thus can control the capacity of the battery. The battery has a rigid casing with an exterior surface thereof, and a rechargeable electrochemical cell within the casing. A plurality of charge contacts are accessible at the exterior surface of the casing and are in conductive contact with the electrochemical cell to allow charging of the electrochemical cell when a current is placed across the charge contacts. The battery also has a charge control circuit in conductive contact with at least the charge contacts and the electrochemical cell, and the control circuit includes a voltage regulator that regulates the charge voltage from the charge contacts to the electrochemical cell.