<P> Alternators are used in modern automobiles to charge the battery and to power the electrical system when its engine is running . </P> <P> Until the 1960s, automobiles used DC dynamo generators with commutators . With the availability of affordable silicon diode rectifiers, alternators were used instead . This was encouraged by the increasing electrical power required for cars in this period, with increasing loads from larger headlamps, electric wipers, heated rear windows and other accessories . </P>

What is the role of alternator in car
find me the text answering this question