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Alternator Terminal Question


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A friend of mine is converting his tractor (also a 350) to a one wire alternator since his generator died. He can have the generator rebuilt but the armature is shot and the the cost of a new one, along with brushes, labor etc. is more than a one wire alternator. He has a small alternator (4" dia) (one wire) so it will fit under the hood nicely. The problem is the terminals are foreign to me. He wants to run an exciter circuit and a voltage sensing wire, but not sure how to connect them - or if they can be connected. I'm familiar with a 10si unit, but have no idea what to tell him when it comes to this alternator. On my 10si I ran an exciter from terminal 1 to a light then to the ACC post on my starter switch. Terminal 2 went to the + post on the starter. The Battery lug goes to the + side of my ammeter. Then to the starter post connected with my main battery cable and the terminal 2 wire.

There are no labels for the 2 terminals (like 1 and 2) but he does have a diagram his brother gave him and I'm attaching that. The diagram says the terminals are IG and L (L/Trio)...?

The alternator is like new, but I believe this is an aftermarket thing for an older GMC or Chevy pickup.

Can this alternator be excited and can he run a sensing wire from the alternator to the starter motor connection?

Any help would be much appreciated!!!

Alternator Terminals.jpg

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If reg. Type IR means internally regulated. Then this is a two wire alternator. IG would be your exciter wire. L is not needed. Voltage will be internally sensed. If IG is connected to ignition plus as indicated. Diode may or may not be required. If hooked to accessory as you did . No diode needed. Also will work with or without a light or resistor in that line

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THANKS to all of you!!

Yeah... after some more research I found out that this one wire alternator is fairly common on Asian made vehicles. No name on the thing at all!

Sooo... I talked to m buddy and told him we'll connect the output of the unit to the starter bus, add a voltmeter and he'll be able to monitor whether it's charging the battery or not. That said, it worked flawlessly and exited when the tractor reached about 750RPMs. He's happy that he has another gauge that works as his ammeter has measured its' last amp!!! LOL!

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Normally you would run the alternator through the ammeter.

As a shortcut you can move the wire from the GEN terminal on the regulator to the BAT terminal on the regulator.

Then, install your one-wire alternator and use the wire from the A terminal on the old generator as your charge line.

Finally, swap the leads on the ammeter so it reads right when charging.

This allows you to use the tractor's existing wiring.

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I'm not at all familiar with one wire alternators and don't recall ever seeing one.

I'm pretty fair at 12V systems but not alternators. They do have their drawbacks. Knowing that an alternator has to have electricity to produce electricity, supplied juice is 12V DC but produces AC which in turn gets turned into DC voltage on output. Advantage of the old generator system is that it needed nothing to produce DC power or AC power whichever it was designed to produce. Biggest drawback of generators is they were heavy, more than alternators. 

Whichever way you go make sure it's as simple as possible, which in effect makes it more trouble free. As throughout my entire life, I've discovered that more complex is simply that, more complex, with more to go wrong (break). Technology and modern engineering are good, but not good in all things. In my simplified world, high tech is not your friend, only more complex. After all, the first tire was round - yup, last I looked - it's still round....

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