Dual Voltage regulator, no its not what you think.

[acw1]

Good afternoon,

I have a very specific question. I'll list that here so there isn't a book to read, but I'll lay out the situation too.

Question; will a dual voltage regulator a 3135 specifically, work on a non dual voltage generator? (Obviously not with the dual voltage function, only mean as a voltage regulator)

Reason for the question is this, I have a 1097 that came from the gov with a 28v only gen (n-1121-2) and a dual voltage 3135 regulator. This caused days of headache before I finally figured out what the problem was. The problem is since solved with a correct dual voltage gen and regulator.

Annoyingly, the incorrect setup would mostly work. Gen would come on and stay on for a little while, then quit. I would also get spikes with revs, but not always or even usually. Per neihoffs troubleshooting, it appeared the VR was no good. I just didn't have a known good vr to double check with. Then I learned it was the incorrect regulator.

Not being an expert, I would think the VR would still work to regulate the gens voltage to 28, and the dual voltage function just wouldn't do anything. If that is the case, then the VR is no good and I'll toss it.

If it never had a chance to work because it was on the wrong gen (and that didn't fry it) I'll hang onto it. That's the reason for the question at the beginning of this story. Thanks and have a good one!

 

[Mogman]

Interesting, I have never seen a "non dual voltage gen" with an external regulator on a HMMWV, there is a 100A that uses the same regulator and is dual voltage.
The numbers you list do not come up in any search except for this thread.

 

[acw1]

Interesting, I have never seen a "non dual voltage gen" with an external regulator on a HMMWV, there is a 100A that uses the same regulator and is dual voltage.
The numbers you list do not come up in any search except for this thread.

There are some photos of the generator and the regulator as it was on the truck. I found the numbers on Niehoffs website. If you put in the 1211, it list the specs. 200A 28v, dual voltage: NO (both letters capitalized in the listing just to make the punch in the face i got on learning that hurt that much more). Also lists the correct regulator, whose number I don't remember, but isn't 3135.

This 1097 is a three speed 2 door helmet top. So no need for a dual voltage rig with the 3 speed, but was likely rigged with 200A gen for accessories. It had a slave receptical on the back of the battery box as well as the jump port on the front of the bat box. The gen is dated 1992, which is the also the year of the truck, so it is original.

We added some 12v accessories thinking we had a dual voltage truck, so just got a 200 amper dual voltage setup from a 4 speed 1097 and problem solved.

 

[Mogman]

That crosses over to NSN 2920-01-420-9968 per the Niehoff's web site.
I did also look at some of the other military only parts suppliers and it is listed as non-submersible.
The correct regulator is a N3106 and it does not have a 14V tap
Searching for the NSN and all the regular suspects are selling as a dual voltage, I assume they are actually selling the "common" 200A dual voltage in its place.
That is some good information to know, thanks for bringing it to everyone's attention!

 

[Mogman]

Looking at your picture the regulator has one of its plugs capped, I assume that alternator does not have that cable, that would be a good reference to know if somebody is fighting a 200A alt. problem!
I wonder if the 3135 regulator would actually work on that alt but being only single voltage.
Did you test that 3135 on the new alt.?

 

[acw1]

Looking at your picture the regulator has one of its plugs capped, I assume that alternator does not have that cable, that would be a good reference to know if somebody is fighting a 200A alt. problem!
I wonder if the 3135 regulator would actually work on that alt but being only single voltage.
Did you test that 3135 on the new alt.?

That lack of cable was my aha moment. Per Niehoffs diagrams it is called a phase connector. Not knowing what it was or where it came from, I started digging more. That's when I learned there was a difference between the 28v only 200A gens and 28/14v gens. I guess to get the 14v there are phases in the generator, which are attached to the regulator from the generator via the plug on the outside (closest to wheel) of the regulator. Please understand that is a very layman explanation, I know there are a few electric experts on here who can explain the phase part better than i just did.

I have not tested the original 3135 on the new gen, which also has a 3135. There was so much pain in the journey to learn all this that I haven't had the balls to mess with something that is working as intended. We just put in the new one today and it's working flawlessly.

 

[Mogman]

I think it is possible the N3135 would work in that application only without the 14V, it seems if someone had just stuck that regulator on the alt. there would not have been a cap provided to seal the unused connector, it is even chained to the connector, normally these just have plastic caps from the factory.

 

[acw1]

I think it is possible the N3135 would work in that application only without the 14V, it seems if someone had just stuck that regulator on the alt. there would not have been a cap provided to seal the unused connector, it is even chained to the connector, normally these just have plastic caps from the factory.

I'm inclined to agree. My thought is the original vr is just no good. It would be a lot easier if it just didn't work, but it did somewhat work. The troubleshooting led me through the entire wire harness and all the grounds, days of chasing things that weren't problems.

One funny thing for everyone's enjoyment. We (me and my son) read through all the prior forum posts, got ourselves some heavy guage wire and hooked it up the 14v post as everyone suggested to the bottom battery. Checked it with a meter, and 13.8, we are good! A little low, but still charging.

It never crossed my mind that I was just reading voltage from the normal operation of the generator charging both batteries. Big forehead slap on that one!

 

[Mogman]

I did find this in Niehoff docs about the N3135

"Allows single-voltage operation (28 V only).
14 V is not available as a single voltage appli-
cation with this regulator.
— Provides optional 28 V/14 V output only from
the regulator when phase cable from alterna-
tor is connected to regulator."