That's one of the big advantages of an alternator- - - -it can turn several times as fast as a generator without damage. The way the rotor is wound allows the alternator to turn 3-4 times engine speed, or more, which would throw the windings out of a generator armature. That's why an alternator can charge a battery at idle speed- - - -something even a 12V generator was hard-pressed to accomplish. A 6V system usually puts a slight drain on the battery unless the vehicle is driven several miles at highway speed every time the engine is started.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!