Wireless battery charger with automatic impedance characterization and frequency adjustment

A method of operating an electrical charging system to wirelessly charge an energy storage device, said electrical charging system having a power supply configured to source an electrical power having a frequency, a source coil in electrically coupled with the power supply and configured to generate an alternating magnetic field, a capture coil magnetically coupled to said source coil, thereby inducing the capture coil to capture electrical power from the alternating magnetic field, a variable resistor switchably coupled to the capture coil configured to provide a variable resistive load to the capture coil, and controller circuitry communicatively coupled with the power supply, said method comprising the steps of:

• varying a resistance of the variable resistor in response to a command from the controller circuitry to the variable resistor;
• and
• varying the frequency of the electrical power supplied by the power supply in response to a command from the controller circuitry to the power supply.