Alternator wiring

I have come across this on several old tractors. Two wires with the ends exposed but not connected. What does it mean?

Thanks, SE

The alternator you are looking at is a Delco 10SI. If it is a standard alternator,it can operate (kinda) with only one wire hooked up. In your
picture, the white short wire should go to terminal #2 in the side slot.
The redish wire should go to a voltage source that is powered when the ignition is on, BUT, it needs to be connected in series with a diode, or small
light bulb, or 10 ohm resistor. The wire is connected to terminal #1 in that slot. It provides "excite" voltage that starts it charging, but when
started, it will then have 12v applied in the alternator. The bulb, diode (with the line facing the alternator to allow volts to go only toward the
alt, and resistor, which would also limit the current (only one of these is needed) are used to keep the alt voltage from allowing the engine to keep
running with the key off.
Many new replacement and rebuilt one wire alternators do not need any extra wires to that slot. All one wire alternators are actually turned on to a
limited "pilot" standby setting. They will draw a small amount of battery milliamps, so the three wire is preferred by me and others here. While many
feel the tractor is used enough to keep that small parasitic drain irrelevant. Jim

Thanks for the reply Jim. I will study on your answer when my brain is more awake. :wink:

Unlike the excellent technical description given below, I would venture this:
It means that the person who owns that tractor is not very careful and a limb, branch or other obstruction has ripped the wires loose. LOL!

On the technical side, those 10SI alternators can be "CLOCKED" so that the wires are not exposed to abuse.
You do that by carefully removing the 4 bolts holding the rear and front together. You then rotate the rear in relation to the front. Clockwise in this case.

With the one in the picture, if you start that one up then touch the loose red (almost orange) to the hot terminal, I would venture that it would start to charge.
That is IF that alternator is still good. That is a big IF.
HTH
Keith

(quoted from post at 00:16:18 03/04/20) Unlike the excellent technical description given below, I would venture this:
It means that the person who owns that tractor is not very careful and a limb, branch or other obstruction has ripped the wires loose. LOL!

On the technical side, those 10SI alternators can be "CLOCKED" so that the wires are not exposed to abuse.
You do that by carefully removing the 4 bolts holding the rear and front together. You then rotate the rear in relation to the front. Clockwise in this case.

With the one in the picture, if you start that one up then touch the loose red (almost orange) to the hot terminal, I would venture that it would start to charge.
That is IF that alternator is still good. That is a big IF.
HTH
Keith

Click to expand...

"It means that the person who owns that tractor is not very careful and a limb, branch or other obstruction has ripped the wires loose. "

In my experience, it may also mean the tractor "lives" with horses.

I have been working on a friends naa and it only has one wire tomorrow I will have a closer look at it. My old ford pickup only has one too and it charges. Maybe I should have a closer look at too.

(quoted from post at 00:53:06 03/04/20) I have been working on a friends naa and it only has one wire tomorrow I will have a closer look at it. My old ford pickup only has one too and it charges. Maybe I should have a closer look at too.

Click to expand...

Your setup may be correct.
Some of those 10si can be bought or changed to a "Self exciting regulator"
Meaning you only need the single heavy Battery wire to charge.
Sometimes you need to momentarily raise the throttle to excite it.
Tom

Some of those 10si's all you'd have to do is get the engine running and touch the wires to energize it.

The tractor only has about a 16 ga. wire. Not sure about my truck. It's been awhile since I've seen it. Showed it to the guy who works on my starters and such. He said it was ok. I dont worry about charging systems on my tractors much as they sit most of the time. Throw a charger on them a few times a year. Thank you for the info.