High voltage problem "updated"

[Highbanked Hauler]

  What is the maximum voltage out of a Chrysler alternator ?  It is a rebuilt and Mine has been running 15 + on startup and 14 + when running. Well it went to a new high this last weekend,it was up to 16.7 on the volt meter and the multi meter said the same thing.  It boiled the battery a bit and the fan belt was squealing most of the way home. I have changed 3 different types of regulators with no difference. I am wondering if the voltage is so high that the regulator just can't handle it ?

[Bronzedodge]

3 regulators....are they getting a good ground, or is the paint keeping that from happening?  If not that then the alternator.

[Highbanked Hauler]

 I ground the paint off of a spot on the regulators and the firewall also. I'm not sure the regulators are bad, is there a way to test them ?  Also put in a new ground strap from the engine to the firewall.

[Pete in NH]

It sounds like the alternator field is getting a full 12 volts applied to it. This is called full fielding the alternator and the alternator output will go to 17 to 18 volts. It could be a bad regulator, bad regulator ground or something wrong internally with the alternator. I think trying three regulators rules out a bad regulator unless something is damaging them.

A true 69 system if that is what you are working with should only have one field connection, a green wire from the regulator. If this is an electronic 70 and up system you should have a floating field alternator and two field wires  green and blue. A 69 or earlier alternator on a miss wired 70 and up system could produce what you are seeing. A picture of the back of your alternator and one of your regulator would be a big help in sorting this issue out. If I could see your car in person the problem would likely be solved quickly since I can't do that pictures are the next best thing. Alternator rebuilders and parts people don't seem to understand these old systems anymore and you can see some really interesting things happen.

[mopar0166]

I had a simuliar issue, after much talk and trouble shooting, I bought a wire high output alt, problem sovled and reliable.

[Highbanked Hauler]

It sounds like the alternator field is getting a full 12 volts applied to it. This is called full fielding the alternator and the alternator output will go to 17 to 18 volts. It could be a bad regulator, bad regulator ground or something wrong internally with the alternator. I think trying three regulators rules out a bad regulator unless something is damaging them.

A true 69 system if that is what you are working with should only have one field connection, a green wire from the regulator. If this is an electronic 70 and up system you should have a floating field alternator and two field wires  green and blue. A 69 or earlier alternator on a miss wired 70 and up system could produce what you are seeing. A picture of the back of your alternator and one of your regulator would be a big help in sorting this issue out. If I could see your car in person the problem would likely be solved quickly since I can't do that pictures are the next best thing. Alternator rebuilders and parts people don't seem to understand these old systems anymore and you can see some really interesting things happen.

    AND I can't do pictures on here.  Its a round back, single field and the lowest amp. alt. that mopar used. It looks JUST like the original one that came on the car. The regulator  collection is  the blue Mopar performance,  an original points type,  and a reproduction electronic unit that looks original, and the last one I'd have to go get the name.  The points unit was only on a minute as the volt meter went nuts.  With the lights and heater fan on it held at 12-13 volts.

[Pete in NH]

Round back alternators came in two types. 69 and earlier had only one field terminal. 70 and 71 had two field terminals for the new electronic regulator system. Rebuilders often play games with these two types and try to interchange them. So, first make sure you have a real 69 single field terminal unit. If you do, try putting a voltmeter with the positive side of the test meter on the field connection (green wire) and the other negative lead of the meter on a good ground. With the engine running you should read something around 7 to 9 volts depending on engine RPM and alternator load. You should not ever see full battery voltage. IF you do with any of the regulators that is a problem. The blue Mopar Performance types are supposed to be a constant voltage higher voltage type and as far as I know are not recommended for street use.

[mopar0166]

I agree , if you are using an original design charging system it need a good ground especially with two fields

[Highbanked Hauler]

  For whatever the reason the alternator is the problem. I swapped it out and put an old alternator back in  and it was running a little over 13.0 volts with dips down to 11. ish volts which tells me the regulator is working so other than a new alternator it looks like we are operational.   Thanks.