As the title says, I've noticed my idle drops with more electrical draw on the circuit. If I shut off anything(heater/lights have the most effect), the idle instantly goes up by 100 or so rpm.

 

I did just install the 90 amp nissan alternator, thinking this would help, but the problem remains.

 

Any ideas what could be going on?

 

Thanks ahead of time.

Those alternators don`t spin for free.It takes power to generate power.

Higher amp draw = harder to turn.regardless of brand

Hmm I guess I never looked at it that that way. It doesn't seem to me that it would be physically "harder to turn" but rather only a set amount of power available at a certain rpm. So in my mind I'm thinking the lights should be slightly dimmer at low Rpms, but idle should remain the same? I shall do some more research on the subject

There also should be a circuit to increase the idle RPMs slightly when power is drawn from the charging circuit.

Cougar, agreed. But it seems I am expecting too much from an 87 carbed suby.

Hmm I guess I never looked at it that that way. It doesn't seem to me that it would be physically "harder to turn" but rather only a set amount of power available at a certain rpm. So in my mind I'm thinking the lights should be slightly dimmer at low Rpms, but idle should remain the same? I shall do some more research on the subject

I literally is harder to turn. If you hooked up an alternator to a bike and put no load, one headlight, and two headlights on it, the pedals would get harder to move with each step up. Remember that inside of an alternator are magnets and a field winding. When the electrons in the field winding have more stuff pushing them back, it makes it harder for the spinning, motor-driven magnet to push them.

Ah, well thank you for this explanation, its much clearer now!

... literally is harder to turn...

 

Yes, that's true.

 

 

... inside of an alternator are magnets ...

 

Electro-Magnets on the Core... they draw current to work, and thus explains why the effort of turning increases with the amperage output needed.

 

Kind Regards.

Edited March 10, 201412 yr by Loyale 2.7 Turbo