Abstract: A motor vehicle electrical system which is capable of supplying both 12 and 24 volt loads. A pair of 12 volt batteries are permanently connected in series and are charged in series under certain conditions of operation from a 24 volt charging system including an alternating current generator and a bridge rectifier. The output voltage of the 24 volt charging system is maintained substantially constant by a voltage regulator connected with the field of the generator which senses and responds to the output voltage of the bridge rectifier that is applied to the series connected batteries and other 24 volt loads. An auxiliary charging circuit is provided connected between one of the phase windings of the generator and the junction of the series connected batteries for, at times, supplying current to one of the batteries that supplies the 12 volt loads. This circuit includes a series connected silicon controlled rectifier and inductance.