An electronic device comprising: a battery having a plurality of cells that are connected in series; a circuit electrically connected to the battery; and a conductive pattern electrically connected to the circuit, wherein the circuit is configured to: receive a first signal wirelessly from a first external device by using the conductive pattern, charge at least some of the plurality of cells in the battery by using a power of the first signal, generate a second signal by changing a first voltage, that is produced by at least two of the plurality of cells in the battery, into a second voltage that is lower than the first voltage, and wirelessly transmit the second signal to a second external device, the second signal being transmitted by using the conductive pattern.