Universal battery charging system and a method

Claim 1

A battery charger comprising: a source of alternating current; a microprocessor; a watchdog timer circuit to reset said microprocessor upon the failure of said microprocessor to provide a predetermined signal within a predetermined interval of time; a zero crossing detector for providing a signal to said microprocessor whenever the voltage of said alternating current is approximately zero; power distribution means controlled by said microprocessor to supply a desired one-directional portion of said alternating current to the terminals of a battery being charged, said power distribution means including an interlock signal to prevent the supply of said portion to the terminals until specified by said microprocessor; battery connection sensing means to provide to said microprocessor a signal indicative of the attachment of the terminals of the battery to the battery charger; a current sensing circuit to provide an analog signal responsive to said portion; a voltage sensing circuit to provide an analog signal responsively to the amount of voltage potential across the terminals of the battery; a temperature sensing circuit to provide an analog signal responsively to a temperature; analog switch means having plural input terminals, operatively connected to the analog signals provided by the current sensing circuit, voltage sensing circuit and temperature sensing circuit and being controlled by said microprocessor to provide an output analog signal responsively to the analog signal appearing at a selected one of the input terminals; and an analog to digital converter operatively connected to the output analog signal of the analog switch means and providing to the microprocessor a digital signal responsively to the output analog signal.