M915A1 voltage regulator change help

[Westech]

Well the voltage regulator/charger started on fire the other morning. I found a replacement for 80 bucks but am having trouble hooking it up.
The stock one has two extra wires. Anyone know what wire is the STA wire out the back of the alternator?

 

[swbradley1]

It looks to be the stator connection. Does the alternator have three stator connections on it?

You could potentially have all three stator connections coming out of the alternator and the regulator uses them that way. Your new one uses only one stator connection and I don't think it will work.

This shows the Delta or Wye connected alternators and how they work. Nothing else I could find shows three stator connections.

http://www.autoshop101.com/forms/alt_bwoh.pdf

 

[NDT]

All three wires are stator wires, each a different leg of the 3 phases. Looks like your replacement only uses one phase.

 

[Westech]

So.... Can the single regulator be wired in ?

 

[NDT]

I think you may be the guinea pig on that one.

 

[Ferroequinologist]

A screaming deal sometimes is a waste of money. Sorry to hear it might not work. You do have to have all three connections for the regulator to work right. I did a ton of reading into the electrical systems on the 915s.

 

[Tow4]

The 12-24n is only rated for 10 amps. It uses the stator to turn it on. Pick one stator wire and hook it to the 12-24n and tape up or insulate the other two separately that you don't use.

Since you already have it, use it. If you can get an OE, I would do that.

 

[Westech]

OE won't be made until next year. It's a demand based production.

 

[Westech]

So if I don't have all 3 hooked up it won't charge?
So I should just get a 12v alternator civy unit ?

 

[Tow4]

So if I don't have all 3 hooked up it won't charge?
So I should just get a 12v alternator civy unit ?

I don't know about the alternator itself. You could try checking the B+ terminal with the engine running to see if it's charging on the 12 volt side.

The 12-24n is for charging at 24 volts from a 12 volt alternator. I think the M915A1 is all 12 volts except the starter and the military trailer lights and maybe the blackout lights. I just got mine and haven't got into the electrical system yet. Fortunately it all works, but if my starter ever takes a crap, it's getting replaced with a 12 volt unit.

I worked for Transpo and later WAI for about 16 years as a mechanical designer/engineer. I still have friends that work there and I drop by to visit once in a while. I emailed a EE buddy this morning to ask the details on how the 12-24n works. He said it would work, but his advice was to get an OE because of the low current output. YMMV. Good luck.

 

[Artisan]

Scary stuff, and it seems to happen a lot to these trucks.
I can only assume my M916 is a fire waiting to happen.
Other than installing a flame out system specifically for
this area is there anything I can do to prevent this failure?

 

[NDT]

I don't know about the alternator itself. You could try checking the B+ terminal with the engine running to see if it's charging on the 12 volt side.

The 12-24n is for charging at 24 volts from a 12 volt alternator. I think the M915A1 is all 12 volts except the starter and the military trailer lights and maybe the blackout lights. I just got mine and haven't got into the electrical system yet. Fortunately it all works, but if my starter ever takes a crap, it's getting replaced with a 12 volt unit.

I worked for Transpo and later WAI for about 16 years as a mechanical designer/engineer. I still have friends that work there and I drop by to visit once in a while. I emailed a EE buddy this morning to ask the details on how the 12-24n works. He said it would work, but his advice was to get an OE because of the low current output. YMMV. Good luck.

Neat back story!

Heck, the stock unit only puts out 16 amps and it catches fire randomly!

The stock alternator (Leece Neville) is just a plain jane 85 amp 12 volt alternator that happens to have 3 leads coming from it to feed AC to the transformer-regulator-smoke generator.

 

[R Racing]

I upgraded my m920 to a fixed 130 amp 12v with a 24v step up unit mounted separately since I have a 24v ac unit in it . it wasn't cheap but it works very well.

 

[Westech]

So only use one of the wires to the sta post ?

 

[Tow4]

Well after looking at my M915A1 today, guess what I found on the back of the alternator!



I'll be emailling my buddy tomorrow to pick one up for me so I have a spare!

 

[Westech]

Can you take some mire pictures ? We are still having issues with mine. Thank you !!

 

[Tow4]

Where it is I can't get any good pictures. It's the same as the pictures in the OP. What is your question? The hook up is pretty straight forward. The stator only turns on the 12-24N so if your alt has 3 stator wires, I would hook up just one of them to the 12-24N.