Power transmitting device having wire-free power transfer safety detection

A machine-readable medium comprising one or more instructions that when executed cause a controller to perform one or more operations to:

• provide power to a plurality of power transfer contacts based on a plurality of time periods having a frequency shifted such that a length of a second one of the time periods is different than a length of a first one of the time period,
• disconnect power to the power transfer contacts during a plurality of test time durations, and
• obtain data during the plurality of test time durations
• provide wire-free power transfer to the receiving device at times other than the test time durations.

A method of power transfer to a receiving device comprising:

• providing power to a plurality of power transfer contacts based on a plurality of time periods having a frequency shifted such that a length of a second one of the time periods is different than a length of a first one of the time period,
• disconnecting power to the power transfer contacts during a plurality of test time durations,
• obtaining data during the plurality of test time durations, and
• providing wire-free power transfer to the receiving device at times other than the test time durations.