View Full Version : Why generators?

12-12-2013, 06:50 PM
I wondered why did manufacturers install generators on cars for sixty years when alternators have so many advantages. Alternators are not a recent invention. Nicola Tesla patented a practical "high-frequency" alternator in 1891. I read up on it, and the reason that alternators were not commonly put in cars earlier than 1960 was due to the lack of a simple part.

Generators were used first because they produce DC current.

Alternators were not used because they produce AC.

In order to convert the AC to DC, you need a rectifier circuit that is made with diodes (a one way valve). Before the mid 1950's the only diodes that available were either electronic vacuum tubes or inefficient natural crystals. Some special use vehicles such as police cars or ambulances with vacuum tube two-way radios that used a lot of electrical power did use alternator systems. But in general, a generator was a whole lot simpler and much more reliable than an alternator with a vacuum tube rectifier.

In the mid 1950's simple, efficient, inexpensive, reliable solid state silicon diodes became available and they opened up a new world of possibilities. Chrylsler patented a rectifier made with solid state diodes that converted AC to DC and put an alternator in their all new 1960 Valiant. The rest is history.