A method and apparatus for supplying cordless power to a remotely-located load device. A first power supply unit of a portable power supply system is configured to operate in a charge receive mode and/or a charge supply mode. When the first power supply unit is in the charge receive mode, a first energy storage device of the first power supply unit is configured to receive electrical energy via a first switch from one of a second power supply unit or an external power source. When the first power supply unit is in the charge supply mode, the first energy storage device of the first power supply unit is configured to supply electrical energy via a second switch to one of a third power supply unit or a remotely-located load device.