Abstract: A portable battery charger has a built-in, retractable connector for charging a portable electronic device. In a first position, a first connector is exposed to the outside of the portable battery charger, to be inserted into a power supply apparatus for charging a reserve battery in the portable battery charger. In a second position, a second connector is exposed to the outside of the portable battery charger, to be inserted into a portable electronic device for charging the portable electronic device. In a third position, both the first and second connectors are covered in the case of the portable battery charger.

Abstract: A battery case has a recessed space for receiving a portable electronic device. When the portable electronic device is placed in the battery case, a supplemental battery in the battery case is able to charge an original battery of the portable electronic device. The battery case has a first supplemental connector capable of being electrically coupled to an original inner connector of the portable electronic device, and a second supplemental connector exposed to the outside of the battery case. The second supplemental connector is configured to be compatible with an original outer connector of an original extension cable that comes with the original product package of the portable electronic device, such that the original outer connector can be inserted into the second supplemental connector of the battery case.