A system including a carrier having a plurality of receptacles configured to receive rechargeable, removable battery packs, an AC power input connector for connecting to an AC power supply, a power output connector, a discharge/charge mode switch for switching between (1) a charging mode of operation that charges the battery packs using electrical power input through at least one of the power input connectors and (2) a discharging mode of operation that outputs electrical power from the battery packs through the power output connector, the charge/discharge control module controlling a plurality of charging switches to provide a charging current to the battery packs and an inverter electrically connected to the power output connector for providing an AC output signal at the power output connector.