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Woodfin · 06-13-2016, 05:30 PM

Duster,

It is completely acceptable to have more alternator output than your system requires. An alternator only puts out the amperage required by the load.

It is common to see 85 amp - 100 amp rated alternators on drag race cars.

Personally, I chose pulley sizes that spin the alternator about 20% - 25% faster than the engine.

Example - 7200 engine RPM x 125% overdrive = 9000 alternator RPM.

Another example - 1200 engine idle RPM x 125% overdrive = 1500 alternator RPM. That is enough alternator speed at idle and does not over speed the alternator at high engine RPM

06-13-2016, 05:30 PM	#3
Woodfin Senior Member Join Date: Sep 2006 Location: Kilgore TX Posts: 540 Likes: 8 Liked 288 Times in 109 Posts	Re: Recommended amperage for an alternator Duster, It is completely acceptable to have more alternator output than your system requires. An alternator only puts out the amperage required by the load. It is common to see 85 amp - 100 amp rated alternators on drag race cars. Personally, I chose pulley sizes that spin the alternator about 20% - 25% faster than the engine. Example - 7200 engine RPM x 125% overdrive = 9000 alternator RPM. Another example - 1200 engine idle RPM x 125% overdrive = 1500 alternator RPM. That is enough alternator speed at idle and does not over speed the alternator at high engine RPM