According to an embodiment, the PCBA 135 includes load balancing circuitry and power regulating circuits to transfer power from the power source to the battery 130 and to the connected second device and/or the inserted earbuds 200-1 and 200-2. As can be understood, the device 100 is a portable charging device that can be used to charge other devices and to charge inserted wireless headphones while not connected to (e.g., plugged into) a power source, or while connected to (plugged into) a power source.

Referring to FIG. 10, an in-ear wireless headphone (earbud) 200 includes a stem portion 209, a rechargeable battery 205 in the stem portion 209, and an electrical connector (contact) 210 at a bottom of the stem portion 209, which is connected to the battery 205, so that the battery 205 in the earbud 200 can be charged. The battery 205 is charged via the contact 210, which connects to a contact 124 at the bottom of a cavity 123 in the device 100. The earbud 200 further includes circuitry 215 and a driver 220 which extends ear portion 225. The driver 220 can include a magnet and a speaker diaphragm. The circuitry 215 includes controlling circuitry for operating the earbud 200 and recharging capabilities.