Methods and apparatus for wireless charging are provided. Transmission power transmitted from a wireless power transmitter is received at a power receiver of a wireless power receiver. A battery of the wireless power receiver is charged with the received transmission power. It is determined whether the battery is fully charged. A packet from a communication unit of the wireless power receiver is transmitted to the wireless power transmitter when the battery is fully charged. An auxiliary charge of the battery is performed by receiving strength-reduced transmission power from the wireless power transmitter.