Method and apparatus for a receiving device to wirelessly receive electric power from a transmitting device. A power capacity is configured at the receiving device, based on a default power capacity known by both the receiving device and the transmitting device. A first value of a dependent parameter is read. The dependent parameter is associated with the electric power and varies in accordance with an independent parameter adjustable by the transmitting device. A second value of the dependent parameter is then read. A maximum power capacity of the transmitting device is identified based on at least the first and second values and a predetermined threshold. The electric power is then received from the transmitting device.