The present disclosure relates to a method for aligning a smartphone providing NFC wireless power for charging a battery of a device, the method comprising: emitting, with a first NFC antenna of the smartphone, an NFC field for wirelessly charging the battery of the device comprising a second NFC antenna; obtaining, with the smartphone, a measured value of a signal representative of the NFC field strength between the smartphone and the device; determining, by the smartphone, a range of values of a plurality of ranges of values the measured value belongs; and emitting, by the smartphone, at least one notification signal to a user with a frequency determined by the determined range of values.