One embodiment of the invention is directed to a rechargeable battery pack configured to provide power to a device that also accepts at least one standard non-rechargeable battery. The rechargeable battery pack comprises a housing for housing at least one battery cell and recharging circuitry. The at least one battery cell and the recharging circuitry is be housed substantially within the housing. The recharging circuitry is coupled with the at least one battery cell. The recharging circuitry is configured to charge the at least one battery cell when the battery pack is inserted into the device that also accepts at least one non-rechargeable battery. The rechargeable battery back further comprises a protection circuit coupled with the recharging circuitry.