All or nothing alternator conversion

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dhowlan

dhowlan

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I am trying to upgrade my 64 Valiant from the old round back alternator to a nippondenso alternator. Specifically, I have a Remy 94616 that in the books goes to a 1991 B150 van. The regulator is a Standard VR128.

I have already bypassed the ammeter. The charge wire is 8 ga and goes through a fuse to the starter relay post. And I should mention that the old alternator was fine, I just wanted to get the output at idle. The phrase if it ain't broke, don't fix it keeps coming to mind.

The first attempt was as follows. I hooked the wires up exactly as the old one, with one field wire grounded to the case. The result of that was a fluctuating or pulsating charge of either 14.6 or 15.x volts. All lights would pulsate and it didn't matter what the rpm was. The alternator sounded very much like a dynamo that they used to have on bikes, whirr whirr whirr whirr. so back on went the old alternator. The anomaly in all of this is that when I first put the old one back, it acted similarly with the pulsating lights, but a slightly lower output. After reading many posts, I cleaned many grounds and added a new one just for the regulator straight to the battery. Then the old one was back to normal (or maybe better with the improved grounding :)).

I tried again this morning. I thought perhaps I wasn't supposed to ground the second field wire, but give it ignition on voltage instead. Now I get zero charge. Constant 12.x volts at the battery and at the charge wire connection regardless of rpm.

In between attempts, I took the alternator to the oreillys and had it tested. was "good as new" fwtw. I manually tested the diodes and they are reading ok. I've looked at and read so many posts on this that my eyes are getting blurry. I'm totally stumped.

I would like clarification on whether the second field terminal on the alternator should be grounded or not. I'm not sure what the determining factor is on that. Does it matter which terminal is grounded if that is the way I need to go?

I know I'm missing something. Help please.
 
dhowlan said:
I am trying to upgrade my 64 Valiant from the old round back alternator to a nippondenso alternator. Specifically, I have a Remy 94616 that in the books goes to a 1991 B150 van. The regulator is a Standard VR128.

I have already bypassed the ammeter. The charge wire is 8 ga and goes through a fuse to the starter relay post. And I should mention that the old alternator was fine, I just wanted to get the output at idle. The phrase if it ain't broke, don't fix it keeps coming to mind.

The first attempt was as follows. I hooked the wires up exactly as the old one, with one field wire grounded to the case. The result of that was a fluctuating or pulsating charge of either 14.6 or 15.x volts. All lights would pulsate and it didn't matter what the rpm was. The alternator sounded very much like a dynamo that they used to have on bikes, whirr whirr whirr whirr. so back on went the old alternator. The anomaly in all of this is that when I first put the old one back, it acted similarly with the pulsating lights, but a slightly lower output. After reading many posts, I cleaned many grounds and added a new one just for the regulator straight to the battery. Then the old one was back to normal (or maybe better with the improved grounding :)).

I tried again this morning. I thought perhaps I wasn't supposed to ground the second field wire, but give it ignition on voltage instead. Now I get zero charge. Constant 12.x volts at the battery and at the charge wire connection regardless of rpm.

In between attempts, I took the alternator to the oreillys and had it tested. was "good as new" fwtw. I manually tested the diodes and they are reading ok. I've looked at and read so many posts on this that my eyes are getting blurry. I'm totally stumped.

I would like clarification on whether the second field terminal on the alternator should be grounded or not. I'm not sure what the determining factor is on that. Does it matter which terminal is grounded if that is the way I need to go?

I know I'm missing something. Help please.
Click to expand...

0900c1528025155b.gif
 
Don't know about your particular alternator but most modern alternators are internally regulated.
So 'throw away' / bypass the voltage regulator and try again.
 
spl440 said:
Just installed this alt on my Dart with the wiring as shown and works good. ran the ground wire at the alt to the mounting screw at the newer style regulator.
Click to expand...

Thanks. I think that might be the relevant bit, newer style regulator. I have an electronic vr128. But I think the VR125 might be necessary. I don't know how they function differently. I thought they were same but one has a plug and one doesn't. What VR do you have exactly?
 
BigBlockMopar said:
Don't know about your particular alternator but most modern alternators are internally regulated.
So 'throw away' / bypass the voltage regulator and try again.
Click to expand...
MODERN MOPAR ALTERNATORS such as used on Rams / Dakotas ARE NOT INTERNALLY REGULATED
 
So far as pulsation, you may have hit on a regulator that isn't compatible, or one that is bad. You also may have somehow created a "ground loop" causing the problem. Try running a jumper wire from the ground point on the regulator to the ground on the alternator case. You want a no. 10 or so, or if you don't have, parallel 3 or 4 no 14's etc
 
Thank you. I've swapped back to the old one temporarily. Daily driver and all that. I will try what you suggested next time.

I am going to get the later style (vr125, the one with the triangle plug) regulator and see if that sorts it out. I'll post a follow up either way, brain permitting.

And just to corroborate (not that you need it, almost all the helpful posts I've run across have been yours) this alternator is definitely externally regulated. Says so in the Remy spec sheet.
 
s-l225.jpg
altwiring.gif

yes this is the style to use and the wiring dia.
 
Last edited:
67Dart273 said:
MODERN MOPAR ALTERNATORS such as used on Rams / Dakotas ARE NOT INTERNALLY REGULATED
Click to expand...
I agree, the ecu controls the charge output. I have bypassed the ecu and added external regulators to cure charging problems. Works very well
 
I will put money on the regulator being wrong. Solid state is on/off
Where the electronified one is variable and more load sensitive
 
That alternator is wired exactly the same as a 1970-80's Mopar "square-back". Many posts on here. Post 9 is correct if using the 1970's triangle-connector Vreg. You can even use it with your original square Vreg. You simply ground 1 field terminal (either one) and run the "fld" wire to the other field terminal, again same as for a square-back. And you can buy an electronic version of the 1960's Vreg w/ same wiring and look. Advantage is no change to existing wire harness.

Going further, the later "round connector" alternators (like my 1996 Voyager) are the same w/ just a different connector (90 A or 120 A if AC), though common "57 terminal" (spades) will fit. They later changed to an oval Metri-pak type connector (like my 2002 T&C), but still 2 field terminals and external Vreg. In the 1990's, they moved the Vreg into the engine's PCM. When that circuit fails, a shop would change your PCM at $$$, but many smart truck guys just intercept the low-side field wire (other one is just +12 V IGN) and wire in an old 1970's Vreg. Get 'er done spirit.
 
Sorry for the delay. I finally got it all together on Saturday. Naturally, when I came here to update, the server was offline for a while. :(

It was amazing how much work replacing the regulator was compared to replacing the alternator.
I now have a relay triggered by the original connector and then the regulator signal voltage (fused) is coming straight from the post on the starter relay.
Also, the footprint of the new regulator is larger than the old one. I used an old ceiling light mounting bracket (slotted metal cross that pivots in the middle) to mount it in the same place so I didn't have to make holes or put it somewhere off the firewall.
Also, new wires for pretty much the whole thing because of the new triangular connection and the added relay.

The result of all this, to my great astonishment (was a bit pessimistic at that point), is that it is rock solid all the time at 14.6 volts. In theory, I still feel like grounding the second field terminal should have worked with the old regulator. Clearly, reality did not agree with that theory. In any case, it's all good now. My dome and dash lights have never been so bright at idle.
Thanks for all the input. :thankyou:
 
Reality wins, it is often measured with meters. To help with your theory, old style regulators energized the field wire, when IGN voltage senses too low, the other field connection is internally grounded. The new style regulator/alternator grounds the field terminal, so the other field terminal is powered by IGN circuit. Current flows in a load when voltage exists across it. Since the new style regulator pulls the field to ground to increase field, grounding the the terminal results in both terminal at the same potential, no field current, nor generation. Think of the field as a light bulb, how to complete an electrical circuit. If both terminals are grounded, nothing happens, if both are at powered at same voltage, nothing happens, if one terminal is grounded, the other powered generation happens. A meter can measure the field voltage, hence it does not have to be a mystery.
 
KitCarlson said:
Reality wins, it is often measured with meters. To help with your theory, old style regulators energized the field wire, when IGN voltage senses too low, the other field connection is internally grounded. The new style regulator/alternator grounds the field terminal, so the other field terminal is powered by IGN circuit. Current flows in a load when voltage exists across it. Since the new style regulator pulls the field to ground to increase field, grounding the the terminal results in both terminal at the same potential, no field current, nor generation. Think of the field as a light bulb, how to complete an electrical circuit. If both terminals are grounded, nothing happens, if both are at powered at same voltage, nothing happens, if one terminal is grounded, the other powered generation happens. A meter can measure the field voltage, hence it does not have to be a mystery.
Click to expand...

Thank you.
Where were you with your meter suggestion when I had the old one hooked up? :D

And yes, I believe I understand the difference between the regulators. The old style regulator regulates how much current reaches the alternator (with the alternator case as ground) and the new style regulates how much current goes to ground after passing through the alternator (in on one field wire and out the other). One regulator controls the + side of the field circuit and the other controls the - side of the circuit.

Perhaps you can explain why the "old" regulator was operating in an on off fashion when the second field terminal on the "new" alternator was grounded. Clearly power was being generated, but it was unregulated half the time.
 
dhowlan said:
Thank you.
Where were you with your meter suggestion when I had the old one hooked up? :D

Perhaps you can explain why the "old" regulator was operating in an on off fashion when the second field terminal on the "new" alternator was grounded. Clearly power was being generated, but it was unregulated half the time.
Click to expand...
I spend my time babysitting an active 11 month old grandson, very little free time, but enjoy everyminute.

About your old regulator. Using a meter to measure between ground and IGN terminal of regulator is a good test to determine if regulator is working. The voltage should be about 13.8V, but varies some with temperature, goes up a few tenths cold, and may drop a bit hot. The voltage varies to meet the desired charging requirement for the battery needs.

If the battery voltage is more than a few tenths from the IGN measured voltage, that means undesirable voltage drops in the wiring and connections. The path goes in and out of the bulkhead connector, in series with amp gauge, ignition switch fusible link ...
So the relay you added helps bypass some of the drops ....but is not a cure all.
 
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