Systems, methods and apparatus for wireless charging are disclosed. A charging device has a plurality of charging cells provided on a charging surface, a charging circuit and a controller. The controller may be configured to cause the charging circuit to provide a charging current to a resonant circuit when a receiving device is placed on the charging surface, provide a measurement slot by causing the charging circuit to decrease or terminate the charging current for a period of time and determine whether the receiving device has been removed from the charging surface based on measurement of a characteristic of the resonant circuit during the measurement slot. The characteristic of the resonant circuit may be representative of electromagnetic coupling between a transmitting coil in the resonant circuit and a receiving coil in the receiving device.