Method of controlling a power transfer system for wireless charging of a battery power source of a portable device by a power transfer device, each of the portable device and the power transfer device having a near field communication functionality for data communication by a data communication link between said power transfer device and said portable device, wherein each of said power transfer device and said portable device comprises a plurality of magnetic coils (11, 21, 50, 51) to establish a power transfer link and said data communication link, and a selection circuit for selecting at least one of said plurality of magnetic coils, wherein at least one of the plurality of the magnetic coils is an NFC coil and wherein at least another one of the plurality of the magnetic coils is a power transfer coil, wherein said power transfer device and/or said portable device (20, 40) comprises a controller, the controller comprising: an NFC circuit for driving the NFC coil to establish the data communication link via near field communication, NFC; and a power management unit for driving the power transfer coil to establish the power transfer link; wherein the data communication link requires a tuning by the NFC circuit in conjunction with the respective coil to a frequency range of about 13.56 MHz; and wherein a frequency range for the power transmission link has a range of approximately 430 kHz to approximately 1.8 MHz; the method comprising the steps of: - starting to establish the data communication link between said power transfer device and said portable device, - requesting by said power transfer device said portable device to transmit identification information via said data communication link to said power transfer device, - detecting whether said identification information of said portable device is received by said power transfer device or not, - setting a charging power to be transferred to said portable device, said charging power not exceeding a first predetermined value when said identification information is not received by said power transfer device, - establishing a power transfer link by said power transfer device and transferring said charging power not exceeding said first predetermined value to said portable device, and - selecting, by the selection circuit, the suitable coil out of the NFC coil and the power transfer coil such that these coils (50, 51) operate at the same time. an NFC circuit for driving the NFC coil to establish the data communication link via near field communication, NFC; and a power management unit for driving the power transfer coil to establish the power transfer link; wherein the data communication link requires a tuning by the NFC circuit in conjunction with the respective coil to a frequency range of about 13.56 MHz; and wherein a frequency range for the power transmission link has a range of approximately 430 kHz to approximately 1.8 MHz; the method comprising the steps of: - starting to establish the data communication link between said power transfer device and said portable device, - requesting by said power transfer device said portable device to transmit identification information via said data communication link to said power transfer device, - detecting whether said identification information of said portable device is received by said power transfer device or not, - setting a charging power to be transferred to said portable device, said charging power not exceeding a first predetermined value when said identification information is not received by said power transfer device, - establishing a power transfer link by said power transfer device and transferring said charging power not exceeding said first predetermined value to said portable device, and - selecting, by the selection circuit, the suitable coil out of the NFC coil and the power transfer coil such that these coils (50, 51) operate at the same time. - starting to establish the data communication link between said power transfer device and said portable device, - requesting by said power transfer device said portable device to transmit identification information via said data communication link to said power transfer device, - detecting whether said identification information of said portable device is received by said power transfer device or not, - setting a charging power to be transferred to said portable device, said charging power not exceeding a first predetermined value when said identification information is not received by said power transfer device, - establishing a power transfer link by said power transfer device and transferring said charging power not exceeding said first predetermined value to said portable device, and - selecting, by the selection circuit, the suitable coil out of the NFC coil and the power transfer coil such that these coils (50, 51) operate at the same time.