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One Wire Alt Wiring for Dummies...

DozerDan82

DozerDan82

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I generally consider myself fairly put together mechanically. Electrically I can get by, but I am stumped here.

Got a 1 wire for the money pit.... pulley swap involved the lathe, so putting the old one back on is no longer an option.

I have a plug with two wires going to the alt (regulator on old set up), a positive to the battery and another wire (tach hook up)

The plug has two wires- both neg when key off, key on- one has battery voltage (12.3) one shows 11.5v - but does not read as a positive on my power probe....

So I put the 1 wire on, and used the switched 12v line to T1, and the 11.5v to T2. Start it and it is charging at 14.7v pulled T1 to see what it would do and it started climbing to above 15v, pulled T2 and it stopped all together.

Did I put those two on wrong? The diagrams I see show to put switched power to T1, and to jumper 12v from charge port to T2, but for some reason I can not wrap my grey matter around that.

What am I missing here, I feel like this should be way simpler than it seems.

At this point I am ready to just going back to charging it before I use it again and only running as long as the batteries last :laughing:
 
An internally regulated 10si/12si I’ve always hooked up a wire directly from the positive post on the alt to the battery. Never had an issue.
 
Here -

T1 gets the switched 12V that passes through the alternator light. When it's not charging that terminal goes to ground, which is why the light comes on. When charging that terminal is brought up to 12V (nominal) and you lose the voltage differential, which is why the light goes out.

T2 *can* be jumped directly to the charging post, but its true function is remote sensing - you want that to be from the fuse panel or directly at the battery. The alternator will try to make that one ~14V. If the connection is shitty or something (might be why it reads 11.5), you'll have a higher reading at the charging post (14.7) as it's trying to compensate for whatever is causing the voltage drop - either a bad connection from the charge lead to the battery/system, or the remote sensing wire itself has a bad connection somewhere.

If you jump T2 to the charging post the alternator will always output 14.2Vish, which may or may not be optimal depending on what the rest of the system is doing. It just sits there doing its own thing without any real feedback.

(basically in your case, if the alt is doing a constant 14.7V, you'll want to measure it also directly at the battery itself, it'll likely be a little less)

Click image for larger version Name: alt.gif Views: 0 Size: 17.1 KB ID: 50296
 
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Jeezuz a 1 wire involves running the wire from the battery to the charge stud and that's it. It will self energize. If it has all 3 wires then it isn't much of a 1 wire but can be wired as such. The large wire on the plug goes to the charge stud and the small can go to ignition switched or left off. If left off it'll self energize about 1200 RPM.
 
DWT said:
Jeezuz a 1 wire involves running the wire from the battery to the charge stud and that's it. It will self energize. If it has all 3 wires then it isn't much of a 1 wire but can be wired as such. The large wire on the plug goes to the charge stud and the small can go to ignition switched or left off. If left off it'll self energize about 1200 RPM.
Click to expand...

Not in this case. If I just have the charging post hooked up it DOES NOT CHARGE. I tried that. Hence the post.
 
vetteboy79 said:
Here -

T1 gets the switched 12V that passes through the alternator light. When it's not charging that terminal goes to ground, which is why the light comes on. When charging that terminal is brought up to 12V (nominal) and you lose the voltage differential, which is why the light goes out.

T2 *can* be jumped directly to the charging post, but its true function is remote sensing - you want that to be from the fuse panel or directly at the battery. The alternator will try to make that one ~14V. If the connection is shitty or something (might be why it reads 11.5), you'll have a higher reading at the charging post (14.7) as it's trying to compensate for whatever is causing the voltage drop - either a bad connection from the charge lead to the battery/system, or the remote sensing wire itself has a bad connection somewhere.

If you jump T2 to the charging post the alternator will always output 14.2Vish, which may or may not be optimal depending on what the rest of the system is doing. It just sits there doing its own thing without any real feedback.

(basically in your case, if the alt is doing a constant 14.7V, you'll want to measure it also directly at the battery itself, it'll likely be a little less)

Click to expand...

Yup that is how I did it, I guess I will measure at the battery and see what it does. Or chase that wire back and see what is one the other end.
 
Funny thing about one wire alts, they generally will not self energize until the RPM is up. You have to rev the engine. After that, the alt will charge at idle. You have a commercial diesel engine, so I have no idea what your rpm is.
 
Its been my experience with chevy one wire that u have to run it through a bulb or a resistor. Holly sells a set up for around $20.

Last 4.3l swap into a jeep i did had a Novak harness and they swore it didnt need the resistor but after buning up the regulator in 3 different alts the Holly resistor fixed all my problems

Here is one from speedway with the correct plug.

https://www.speedwaymotors.com/Spee...tm2JJ3cSd_etdjEOcH0rLfJNxpeQ_DYcaAmvLEALw_wcB
 
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