Over Charging

[vandie12]

I've been reading through all the previous posts, and haven't really found an answer to my problem. So here goes and hope someone has an answer. 69 Charger, 383, electronic ignition, also the electronic voltage regulator, is all hooked up to what I've seen on the previous posts, sketches and pictures. I'm still running the old ammeter system in the car, the wiring has been all gone through, main bulk head is in real good shape, with new wiring harness in the engine compartment. Ground strap hooked up from engine to body, also to radiator support, I don't have the one from the steering column to the dash hooked up yet but don't think that is my problem. Anyways the car has been completely restored with everything that needed to be replaced has been. Here is the problem, amp meter shows plus 40 when I rev it up, so I checked the battery voltage from the charging system, at idle about 14 volts and when its rev ed to 2000 it reaches 18 plus volts. This I know will fry the battery in time so what would cause this over charge. I checked the voltage at the battery and also at the alternator with the same reading.

[John_Kunkel]

When you say "electronic regulator" do you mean it's been upgraded to the '70 and later system?

If so, disconnect the green field wire from the alternator and see if it still overcharges...if it does the alternator has an internal short.

If disconnecting the field results in zero charge as it should, either the green wire is shorted to ground somewhere between the alternator and the regulator or the regulator is faulty.

[vandie12]

Yes it has been upgraded to the 70 and up. I took the green wire off the alternator and I still have a charge, so it may be a defective alternator. Will have alternator tested they should tell me if there is a short correct?

[Chryco Psycho]

yes , it sounds like the field is grounded inside

[vandie12]

Had alternator tested and was told at the auto parts place that it is charging with in spec. I told them that I know it charges but it over charges... The guy that was doing the testing didn't seem like he really knew what was going on. Is there a check i can do with a volt meter to see if it has an internal short?   The other thing is if the alternator I have is the correct one.......  I have the 2 terminals on the back besides the positive, one says grd the other says fld, I have the green running to the grd and the blue running to the field, Is this correct? Also on the alternator itself, the ground terminal on the alternator is grounded right to the alternator and the fld is insulated.

[flyinlow]

On electronic regulator alternators (2 field wires) the green wire goes from the alt. field circuit to the voltage regulator where it varys the current getting to ground, varying field strength and thus alt. output. If the green wire terminal touches the alt. frame or any other grounded part of the car ,the alt. will charge at its maximum output. I would think an Ohm meter would show if the field is grounded. One probe on a field terminal and one probe on the alt. housing. Disconnect the battery first.

[vandie12]

Now I'm confused, the green wire that goes to the elec regulator to the alt I thought is the ground, and the blue from the reg wire goes to field on alternator. When I hook my voltage meter up to the green wire on the alternator end  (I have it disconnected from the alternator) it shows a ground, I disconnect the plug from the regulator and it doesn't show ground. If it is the way you say it is what is the blue wire for?

[John_Kunkel]

Had alternator tested and was told at the auto parts place that it is charging with in spec. I told them that I know it charges but it over charges... The guy that was doing the testing didn't seem like he really knew what was going on.

He didn't. The test bench does the same thing as shorting a field to ground, it tests the maximum output of the unit which you already know it will put out maximum.

If you have a multimeter, check for continuity between the field spade terminals and the case...if either field reads continuity to the case there is an internal short.

[vandie12]

Ok I have only 1 field on the case (that was hooked to the Blue wire) the other is a ground, that was hooked to the green wire coming from the regulator. I did the test for the fld on the altternator and it was shorted to the case, I ordered another alternator with 2 fields, and a new regulator. As I said in my last post when i ran a ground test on the regulator I found  the green wire was grounded, so there must be an issue with the regulator since it was hooked up to the direct ground on the alternator. 

[flyinlow]

I am confused too. A 69 Charger came with a single field wire mechnical voltage regulator. (cubed shaped)

Newer Mopars came with an isolated field alternator with two field terminals and an electronic regulator. ( flat with a two wire plug secured with retaining clips)

When you stated an electronic regulator, I assumed someone had upgraded your chargeing system.

The blue wire to the newer style alternator is 12vdc feed to the alternator field . The green wire then completes the circuit to the electronic regulator where it determines how well to ground the field .

Older style single wire alternators ground the field internally in the alternator. Field strength is determined by the amount of current comimg from the regulator.

Hope I remembered this right its been a while since I played with a stock Mopar system. If not maybe John will correct me.

[vandie12]

The system had been upgraded by previous owner, to the newer electronic system, but what I have found is that they had an alternator on there from the old system. The alt had a ground and field terminal, rather than 2 fld terminals for the green and blue wires. When I put it all together I didn't think about it having the wrong alt setup. Once the engine had been started and I checked the system did I find the over charge.

[flyinlow]

Yea that would make it charge at its maximum. I newer style isolated field alternator should get you going if the wiring is good.   

[vandie12]

Thanks guys, new alternator with 2 flds, and new regulator, did the trick. The marrow of the story don't trust anything anyone else has done to be right.