According to one embodiment, a system includes an electronic device and an extension device. The electronic device includes a first connector to which a first AC adapter is connected, a first control IC including a first power supply controller, and a first charger IC to charge a first battery with power from the first AC adapter in response to an instruction from the first power supply controller. The extension device includes a second connector to which a second AC adapter is connected, a second control IC including a second power supply controller, and a second charger IC to charge a second battery with power from the second AC adapter in response to an instruction from the second power supply controller.