Abstract: A method of and apparatus (10) for controlling the charging of a battery (17) wherein determination of a preselected point in the battery charging operation is determined by a circuit portion (22) determining the duty cycle of digitized waveform information provided by a digitizing circuit portion (21). The digitizing circuit portion provides an output having opposite states depending on the voltage appearing across the battery (17) being charged and a reference voltage provided by the control apparatus (10). The apparatus includes a capacitor (61) having a voltage corresponding to the duty cycle of the digitized information. An output transducer (23) is controlled by the capacitor voltage and additional circuitry of the apparatus (10) including a detecting zener diode (17) so as to cause the transducer to provide an output signal when the effective voltage on the capacitor rises to the zener diode nominal voltage so as to provide current therethrough for effecting the desired control of the transducer (23).