Abstract: A method and apparatus is disclosed for automatic control of battery maintenance including fast recharge and equalizing of the voltages on individual cells of the battery. The charging current through a resistance in series with the battery is monitored, and in response, a control circuit energizes a relay which controls the output voltage of a power supply used to charge the battery and drive a load. The control circuit includes a clock, connected to a recharge counter, which effects the recharge process for a predetermined period of time. The recharge counter is connected to the relay which regulates the output voltage of the power supply. The control circuit also includes a battery current sensor, which monitors the charging current of the battery, and a second counter, which provides an enabling signal to the relay for initiating a longer cycle which equalizes the charges on individual cells of the battery if the battery has been recharged from a severely discharge state.

Abstract: A pulse width modulation (PWM) converter circuit for transforming a first DC voltage into a secondvoltage (AC or DC), wherein the magnitude of the second voltage is regulated by the converter circuit. The converter circuit comprises a clock circuit, a master pulse width modulator (PWM) circuit and n slave pulse width modulator (PWM) circuits. The clock circuit provides a symmetrical train of rectangular pulses on each of n+1 conductors, wherein only one pulse occurs on any one of the conductors at one time. The master PWM means is responsive both to the train of pulses on one of the n+1 conductors and to a feedback signal indicative of the magnitude of the second voltage; the master PWM means controls the flow of current, due to the first DC voltage, through a portion of a transformer primary winding.