The present disclosure described herein relates to wireless power transfer systems and methods that efficiently and safely transfer power to electronic devices. In an aspect of the disclosure, a method for wirelessly transmitting power is provided. The method includes during a first time period, transmitting power at a first power level from a wireless power transmitter to the wireless power receiver. The method further includes determining a frequency for transmitting power at a second power level based on a ratio of a current level of the wireless power receiver to a current level of a wireless power transmitter at the first power level. The method further includes during a second time period, transmitting power at the second power level and at the frequency, the first power level lower than the second power level.