28v / 14v Alternator hookup question . . .

[Ddk2001]

Moved to HMMWV forum . . .

 

[Ddk2001]

My HMMWV has the Niehoff N3135 Dual Voltage Regulator (28v / 14v). It was installed when I purchased it. I looked up the Niehoff installation instructions - have a question about the install - and about getting 12v power from my existing 2-battery set up.

I've done my fair share of wiring in the various cars and boats I've owned - but I've not had to mess with a 24v system - so I want to make sure I understand how this all works.

First - I've taken a picture of my battery box. Do I have the concept of bottom (lower) battery correct? I understand that I would run a wire (8 or 6ga) from the 14v output on the Alternator to the (+) side of the bottom battery - about could then run a 12v bus bar off of that terminal. Is that how the setup is supposed to work? Is it really that simple?

Next question - I'm not certain it was originally installed correctly. According to Niehoff - if it's not being used (when installed) for 14v, there should be a cap with a chain that gets connected to the slave port (bottom right of alternator in my picture). Here's the install docs from Niehoff: http://www.ceniehoff.com/Documents/Ctrl_Hyperlink/II0028D_uid121020091201492.pdf I've read some posts that say you should ground the 14v terminal when not using for 14v supply - but that's not what the installation instructions say. That said - as you can see from the pics of my alternator - there's not cap and chain to the loop on the back of the alternator. Problem?

EDIT - think I answered my own second question. The install says when using the N1225-1 or the N1505-1 alternator - the alternator phase cable gets attached - not the cap w/ chain. Just checked my truck - I've got the N1225-1 alternator - so looks like install was proper.

Thx.
-D

View attachment 660918View attachment 660921

 

[doghead]

Do not post multiple threads on the same topic in multiple forums.

 

[ryanruck]

Yep, it really is that simple. My truck came like yours and a couple others I've seen with the 200A dual voltage setup, with the 14v not connected. Not really sure why leaving that 14v tap unconnected seems to be SOP for trucks that get upgraded to the 200A alternator.

Just run a cable from the 14v tap to the positive on the rearmost battery and that's it. I opted for 0 gauge wire myself. I think 6AWG would be pushing it and 8AWG would definitely be too small, IMHO. Only $20 for 25' of 0 AWG so I figured why skimp. Some nice crimp on ring terminals too.

 

[Ddk2001]

I opted for 0 gauge wire myself. I think 6AWG would be pushing it and 8AWG would definitely be too small, IMHO. Only $20 for 25' of 0 AWG so I figured why skimp. Some nice crimp on ring terminals too.

thanks. The 14v output from the Niehoff N3135 is max 50amp. 6AWG is more than sufficient to carry that load (at that short length). That said - I'll probably make some 4AWG cables to get it done.

 

[86humv]

The 14 v tap is used when the truck has a 4L80e trans....its computer is 12 vdc.

 

[juanprado]

Can the tap be used to feed a 12v fuse panel?

I am specifically thinking of using it with the pulse distribution system 12/24 12v feed. It was installed in some of the hmmwv taping the rear battery but I suspect that was before the 200amp dual voltage niehoff.

 

[Ddk2001]

Can the tap be used to feed a 12v fuse panel?
I am specifically thinking of using it with the pulse distribution system 12/24 12v feed. It was installed in some of the hmmwv taping the rear battery but I suspect that was before the 200amp dual voltage niehoff.

my understanding is the 12v fuse block should come off the bottom battery - not a direct feed off the alternator. I've been told (but don't know for sure) that the battery "condtions" the current from the alternator. The alternator will provide 14v - and will have an occasional minor spike. I don't know if it's true - but have been told and taught to always power equipment at the battery. YMMV.

I'm going to run a small marine distribution block off the bottom battery for a Bluetooth receiver and amp - and a couple of USB charging ports.

 

[Retiredwarhorses]

The battery's are refered to as "front or rear" not upper or lower...in your application it is the rear battery.

 

[McSpeed]

I am about to do this too, and please forgive me as I've read multiple threads and the N3134 documents but want to get it right. I just picked up a switch panel to mount so I can put in some interior lights, and of course I'd like a 12 volt port for a few basic things.

#1 - pull healthy gauge wire from the 14V terminal to the rear most battery (nearest the back bumper) POSITIVE terminal
#2 - run a wire from the rear most battery positive terminal over to a fuse panel.
#4 - run power from my fuse panel to my accessories.
#5 - chassis ground all accessories

Am I missing anything?

 

[Ddk2001]

I am about to do this too, and please forgive me as I've read multiple threads and the N3134 documents but want to get it right. I just picked up a switch panel to mount so I can put in some interior lights, and of course I'd like a 12 volt port for a few basic things.

#1 - pull healthy gauge wire from the 14V terminal to the rear most battery (nearest the back bumper) POSITIVE terminal
#2 - run a wire from the rear most battery positive terminal over to a fuse panel.
#4 - run power from my fuse panel to my accessories.
#5 - chassis ground all accessories

Am I missing anything?

I ran a positive and ground (neg) from the rear battery to a small fuse panel. Everything grounded back to the 12v battery . . . .

 

[McSpeed]

Oh wait. Looking now. I have a wire currently on the 14+ out put on the back of the generator. It looks like it goes to a ground on the back of the drivers cylinder head. How is this possible????

 

[McSpeed]

Yes. Just confirmed. It goes to ground.

I thought i understood but now i am confused what to do.

 

[Retiredwarhorses]

Yes. Just confirmed. It goes to ground.

I thought i understood but now i am confused what to do.

the 14v tap is grounded via a jumper to the regulator mount screw When not equipped to suppprt a load.
this is per the TM, when you go to use it, remove the ground and run 8ga wire to rear battery positive.
the 200amp is the direct replacement for 60amp gen in all trucks, it was designed for the 4l80e equipped trucks.

 

[McSpeed]

That blows my mind. I never imagined grounding a positive volt output. Next chore is to find the safest routing for the new cable.

 

[Retiredwarhorses]

That blows my mind. I never imagined grounding a positive volt output. Next chore is to find the safest routing for the new cable.

The 8ga tie wraps to the 200amp feed cable and follows the same route

 

[McSpeed]

Got it up and running!!! Thanks!!!!

anybody know if there are backup lights housed into the harness already at the NATO plug? I should probably ask that in another thread.

 

[Crapgame]

I have the 200v 14/28v alternator on my 6.5l GEP Turbo long block, but the demil folks broke the Amphenol connector on the voltage regulator. Does anybody know the Amphenol 3 pin connector part number?

 

[86humv]

Got it up and running!!! Thanks!!!!

anybody know if there are backup lights housed into the harness already at the NATO plug? I should probably ask that in another thread.

No, unless you have an Ambulance harness.