Patent ID: 7843088

Claim:
A power supply apparatus connectable/disconnectable to a DC device at a single output, comprising: a first AC to DC power supply for supplying power to the device, producing a first power level and having an AC power source input; and a control circuit for turning the first power supply on and off when the device is disconnected from the apparatus and when the device is recharged said control circuit comprising: a second AC to DC power supply producing a second power level less than the first power level; a first diode (anode) connected to the first power supply; a shunt resistor connected between the first diode (cathode) and the output; a second diode connected between the second power supply (anode side) and both the shunt resistor and the first diode (cathode side), second diode cathode; a current shunt monitoring circuit connected across the shunt resistor and producing a control signal; and a solid state normal open relay connected to the AC power source input of the first power supply, connected to the current shunt monitoring circuit and controlled by the control signal.