The embodiments relate to a rechargeable battery pack capable of both internal and external charging/output operation. The rechargeable battery pack has an internal connecting port, which is configured to directly connect to an internal electrical contact in an electronic device during an internal charging/output operation when such battery pack is installed inside an electronic device. The rechargeable battery pack also has at least one external connecting port, which is operable during at least one of external charging and output operations of the rechargeable battery pack when the battery pack is removed from the electronic device. The external connecting port allows the rechargeable battery pack to be externally connected to an external charging connecter during an external charging operation or to a second electronic device or second rechargeable battery pack during an external output operation.