Abstract: The invention is a device and system for providing power to a portable electronic device. A battery unit includes a rechargeable battery and is configured to be removably secured to a portable electronic device to provide power thereto. A base unit is configured to receive and charge one or more battery units, either alone or with the battery units secured to portable electronic devices. The battery unit includes a battery charge indicator, which can be a visible signal. An optical bath is defined through the base unit to transmit the visible signal of the battery unit to a base unit battery charge display.