Patent ID: 7482781

Claim:
Power supply apparatus for supplying a direct voltage to a load that is connected to a first terminal, the supply apparatus comprising: a rechargeable battery for connection to a second terminal, and a voltage generator for recharging said battery and supplying power to said load; first control means for controlledly supplying current from said voltage generator to said first terminal so as to control supply of current from said voltage generator to said load and for preventing reverse flow of current from said first terminal to said voltage generator, said first control means being arranged to present selectively a high impedance state, a low impedance state or a controlled current state, said controlled current state controlling the magnitude of the current supplied by said first control means to said load; and second control means for controlledly supplying current between said first and second terminals so as to control supply of current from said voltage generator through said first control means to said battery and from said battery to said load.