Alternator Charging Issues

[Sixt8Chrgr]

I know there are many posts on the board about alt. charging problems, and I reviewed many but did not see one that was similar to mine. I have a 68 Charger, single field alt. with a 383 HP.

My amp guage usually read +/- 10 amps charging. Now when I am running is reads about -5 amps and maybe will get up to 0. I checked the voltage at the battery and got 12.35 volts and checked it at the alt and got the same reading with the engine off. When running at idlle, I get about 11.50 volts at the battery and slightly higher at the alternator. When running about 2000 rpms I get 12.8 at the alternator and the same at the battery. My question is what would have changed to cause a negative charging situation from a positive. Also the alternator and voltage regulator are 45 days old. NAPA products. I have checked for burnt wires, loose wires, etc.

Thanks for any help.



Lawrence

[Plumcrazy]

With the engine running and a voltmeter hooked up, run a jumper wire from the positive battery terminal to the field connection at the alternator.  Just connect it for a short time. If the voltage goes up you probably have a bad regulator.  If it doesn't, then the problem is in the alternator.

[Sixt8Chrgr]

Where do I hook up the voltmeter? There are 3 conncections on the back of the alternator. One Batt. and two others. Which other do I hook up the jumper to?

[Nacho-RT74]

so you have electronic regulator and alt upgrade... green and blue wires drives 12 volts. green negative and blue positive, with key in RUN position. Those are input to alt.

black wire ( stud ) is output to ammeter then to batt... so constantly have 12 volts ( positive )

negative charging source is thorught alt chassis

[Sixt8Chrgr]

Maybe I was just being paranoid, this past weekend I was driving the car during the day and had a normal charging situation. When I last noticed a negative charging situation was when I had the lights on driving at night. It seems to me that I should still have a positive charging situation driving with all accessories on? Shouldn't I have about 13.7 volts at the alt. output? I only had 12.7. I am going to drive the car to work today and see what happens.

Thanks

[Plumcrazy]

With the lights on,it's normal to see a discharge reading on the ammeter when you are stopped at a light.  Even a properly working alternator doesn't have much output at low RPM's.  When you are driving,the ammeter should show some charge.