single wire alternator

[snaus32]

I have a new motor im instilling in my 67. Its a crate L31 vortec and has a single wire alternator on it. How do i wire it? My 327 had the two wire set up, I have the positive wire but where do i hook up the white lead for the voltage gauge? do i just put them both on the same terminal?

[sleepertruck72]

https://www.summitracing.com/parts/p...ss-performance

I did not use a volt gauge, but I used this painless wiring pigtail...after I found out my alternator fried because I didn't have a charging lamp as a load in the circuit

[VetteVet]

The best place to wire it is to the same place the original alternator output wire was ran. Inside the harness is a soldered junction with four red wires connected together, it is located in the main harness by the left headlight. They are all 12 gauge wires and one of them comes from the battery over the radiator, one goes from the junction to the firewall connector for cab power, one comes from the external voltage regulator, and the fourth one is the output wire for the alternator. If you don't plan to upgrade this wire to a 10 or 8 gauge, you can just splice it to the red wire from the voltage regulator since you will not use it any longer.





Here is what the junction looks like in my 67 harness. If you have a gauge dash panel you will also have a black or black/white stripe wire also connected with the four red wires. It is for the battery gauge (ammeter), and there should be a solid black wire connected to the junction bolt on the right fender by the battery which is the other battery gauge wire. If you wire the one-wire alternator to this junction bolt like so many guys do, the alternator will charge but the battery gauge will not show any charge or discharge.

Here's a picture of the soldered junction.

[AK49Watson]

I also used a new internally regulated single wire capable alternator, but wired it the original way using the same method above. Works great. I have a factory ammeter, didn't bother wiring it up though.

[VetteVet]

After posting the diagram above I noticed that it was the one that shows how to convert to the internal regulator alternator by jumping the wires in the external regulator plug. All that's needed is an adapter plug for the SI alternator,which is about $5.00 at the auto parts store. No resistor is needed for this conversion and running the blue wire to the no. 2 terminal on the alternator will reduce any voltage drop on the circuit.

With a one-wire alternator, the blue and white wires would not be used and only the large red wire from the back of the alternator needs to be run to the main junction.

Here is how I convert the alternators. It is much cleaner and eliminates the external voltage regulator plug and it's wiring.




Simply run the brown wire from the firewall connector to the no. 1 terminal on the new alternator and run the red wire from the junction to the no. 2 terminal on the alternator. Then upgrade the 12 gauge wire on the back of the alternator to 10 or 8 gauge and run it to the main junction.

[jjzepplin]

I am doing a little hijacking on this thread as I did not want to start a new one but maybe I need to. I have a one wire alternator on my brothers car that I am trying to figure out. It was not showing any charging at the battery so I followed the big red wire on the back to find it disconnected. It had come loose from the not so good squishing of the terminal and not being crimped. I did not have my soldering iron with me and did have my voltage meter. I tested the rear lug and it showed a massive 62 ish volts. Could this be right? I am not connecting that wire before much further testing.

[SeanB242]

If it’s the factory alternator the yes I believe that voltage is right.

Sorrymy bad. I read that wrong. 14 volts. I was thinking you was taking about the output amps.

[jjzepplin]

Its a one wire Powermaster. Shouldn't it be about 14.5 volts?

[VetteVet]

Originally Posted by jjzepplin

Its a one wire Powermaster. Shouldn't it be about 14.5 volts?

You are correct, but if the alternator isn't connected to the vehicle wiring circuit the internal regulator can't sense the vehicle current draw and it defaults to full output, which is usually 16 to 18 volts. You may have a faulty regulator or blown diodes in the alternator.

The output voltage is high but if the amperage is low, less than a few amps, it won't burn up anything. I would be safe and take it to one of the auto parts. stores like AutoZone and get them to test it.

Were you getting DC volts or AC volts on your reading?

[jjzepplin]

DC volts. OH I see what you mean.

[bMr]

FYI. This is a great read: http://www.madelectrical.com/electri...hreewire.shtml

[BCOWANWHEELS]

I run ano 8 wire straight to battery, no problems in severral years

[SeanB242]

Fusible links confuse me. Is it just a matter of a smaller diameter wire in line of what your booking up. Say I have a 12g wire from alternator to my junction block on my core support. I just put like a 6” piece of 14g wire in there or is there more to it than that?

[BCOWANWHEELS]

You,ve got to have a wire thats able to handle alts. Max output.......

[SeanB242]

Amps? I assume. And how do I figure that out?

[VetteVet]

Originally Posted by SeanB242

Fusible links confuse me. Is it just a matter of a smaller diameter wire in line of what your booking up. Say I have a 12g wire from alternator to my junction block on my core support. I just put like a 6” piece of 14g wire in there or is there more to it than that?

Fusible links are special wires made of special material that is designed to burn in two slowly, without flaming up and causing a fire. The current surges drawn by starting motors initially, would blow most fast blow glass fuses used in our trucks or the newer blade types used in the later model vehicles.
There is a slow blow fuse called a maxi-fuse that is designed to handle surges that might work as well.
You shouldn't just slap in a short piece of wire unless it's an emergency and not until you've found the cause of the blown fusible link.

Originally Posted by BCOWANWHEELS

You,ve got to have a wire thats able to handle alts. Max output.......

True, 12 gauge was fine on the factory trucks but as the more modern stuff was added the amperage draw is more than it can handle and the alternators
can now generate well over 100 amps. The thing to remember is not what the alternator can output, but how much is the system going to draw. if all the loads are on at once how many amps are being drawn and is the wire large enough to handle that much current.

Most of the time the system is not running full blast, and the thing to remember is that the alternator is not putting out it;s full capacity all the time. A 12 gauge wire would be enough on our trucks if they were stock even with a 200 amp alternator.
A 10 gauge would be plenty and the 8 gauge will handle about anything short of a winch.

Originally Posted by SeanB242

Amps? I assume. And how do I figure that out?

Your alternator amperage max output is hard to determine without an amp meter. and several loads, and You have to know the rated amps of each load and add them all up, then measure the amperage draw with the alternator running at full output. The rated amperage of an alternator is seldom what it's capable of. In other words a 100 amp alternator most likely will not put out a full 100 amps. Advertising plays a role as always.An easy way to tell how much you need is to add up all the fuses in all the circuits and multiply by 80%. Then add in the amperage of the fans and motors and that will give you an idea of the size of the alternator that you need.

In most cases a 100 amp alternator will do. If you are running compressors or a winch then you'll need more. The newer CS alternators a capable of more output especially at idle but remember, a CS 130 or CS 144 is not the amperage output of the alternator the 130 and 144 means the size of the alternator body in mm. AKA the circumference. Converting to one of these is as simple as converting to the internal regulated SI 10 or 12.

[BCOWANWHEELS]

Most 1 wires are 100 amp

[SeanB242]

Awesome explanation Vette. I can always count on you. I seen someone mention the fusible link should be 4g smaller than the wire you putting it in is that a good general rule?

[VetteVet]

Originally Posted by SeanB242

Awesome explanation Vette. I can always count on you. I seen someone mention the fusible link should be 4g smaller than the wire you putting it in is that a good general rule?

It's pretty much a given. VV