they increase output with higher rpms

i'm not sure why it'd be lower, but it doesnt strike me as odd either.

I saw a higher output alt for my altima (150 amp) actually only output like 75amps at idle vs 80 of my current one, only went up higher at higher revolutions.


to understand how an alternator works:

Understanding Alternators, How alternators work


Even just quickly skimming through it you get an idea.


basically theres one part that moves (controlled by the speed of the belt that you have attached to the alternator that rotates) and one part that doesnt, when the movable part spins, it creates an electric current by the magnetic fields. that electricity is then sent through your batt and the whole car.

*BELOW IS AN ASSUMPTION/UNDERSTANDING THAT I HAVE, NOT TO BE TAKEN AS A TRUTH, IT WILL MOST LIKELY BE DEBUNKED LATER TONIGHT OR TOMORROW*

As far as why higher output alts dont show their true power until at higher revs, thats most likely due to the fact that higher output alts have more winds/coils in the nonmoving part so that when the higher revs do start getting it going it makes a lot more power. I'm guessing that with the higher the coil winds, the more work the alt has to do to make the same power at idle, but when it starts going up higher in revolutions, it really starts going through. VTEC!


I'm just going to wait until Toby or someone chimes in to tell me i'm off and they'll end up explaining it better.