Thread: Idle voltage....Alternator?

Originally Posted by SyntheticShield

Im not so sure that is normal at idle. In order to charge, the alternator has to put out more voltage than the battery voltage of 12 volts. I dont recall ever seeing an alternator put out less than 13 volts at idle, normally its around 13.6 or so. With a voltage booster it should be putting out even more at idle.

I understand. But, There is no car in stock form that idles at 700 rpm's. I have a stage 2 voltage booster and still see right around that. No problems for over a year now. I'm sure if he would put the stock idle tables back he would be seeing the correct amount of voltage

Originally Posted by Sabrewings

Dude, my car idles stock at 650RPM. Most 3800s I've come across idle at ~700 +/-50 depending on the weather and cleanliness of the IAC.

Ok then you tell us what the problem is.

Originally Posted by Sabrewings

Faulty voltage regulator in the alternator or faulty alternator. It's simply having trouble maintaining voltage at idle. My car can maintain up to 15+ volts if the battery is low at 650-700RPMs idle. If it isn't giving you problems while driving, then it really isn't a big deal.

Though, I've seen this be a prelude to an alternator that just gives out. Can't say exactly when or even if. But it's possible.

I was off on my accusation of the idle speed. And agree with you on your above statement. But for the record mine does the same thing....untill around 900 rpm's then it jumps to around 14. something

True