Rechagreable battery packs and related methods

In one embodiment, a rechargeable battery pack can be configured to power an electronic device having a first battery. The rechargeable battery pack can comprise a second battery supplemental to the first battery, an external power input configured to couple to an external power source, a power output for powering the electronic device. The rechargeable battery pack can also comprise a first circuit comprising a first power path between the external power input and the power output, a second power path between the second battery and the power output, and a power switch set. When the external power source is decoupled from the external power input, the first power path is disabled by the power switch set, and the second power path is enabled by the power switch set. When the external power source is coupled to the external power input, the first power path is enabled by the power switch set, and the second power path is disabled by the power switch set. Other examples and embodiments are described herein.