Systems, methods and apparatus for wireless charging are disclosed. An apparatus has a wireless charging apparatus has a battery charging power source coupled to a charging circuit, a plurality of charging cells configured to provide a charging surface, and a controller. The controller may be configured to provide a pulse to the charging circuit, detect a frequency of oscillation of the charging circuit responsive to the pulse or a rate of decay of the oscillation of the charging circuit, and determine that a chargeable device has been placed in proximity to a coil of the charging circuit based on changes in a characteristic of the charging circuit. The pulse may have a duration that is less than half the period of a nominal resonant frequency of the charging circuit.