Three-Wire Delco 10SI/12SI Alternator Question - Hot Rod Forum : Hotrodders Bulletin Board
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Old 03-15-2011, 03:36 PM
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Three-Wire Delco 10SI/12SI Alternator Question

There's a lot of information out there about the three-wire versus one-wire alternator setup, and I'll just share this:

One-Wire versus Three-Wire
http://www.madelectrical.com/electri...hreewire.shtml

Explanation of how the idiot light circut is wired and how it works.
GM 3 wire alternator idiot light hook up

Explanation of how the voltage sensing circut is wired and how it works.
http://www.madelectrical.com/electri...esensing.shtml

And a picture of the wiring using a 1N5408 diode and NOT using the voltage sensing circut.



While the picture suggests a 10-guage wire from the alternator stud, my perference is to use 8-guage wire. And rather than pig-tail the voltage sensing line to the stud, I run a wire to the feed stud of the fuse panel so I can atually get some value from voltage sensing.

Anyway, enough sharing. My question is this:

In all I 've read it's not been clear whether any Delco 10SI/12SI can be used in three-wire mode just by connecting all three wires or if only some of the built-in regulators are capable of doing it.

What's the answer?

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Old 03-15-2011, 04:04 PM
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The main difference between a 1 wire and a 3 wire is the regulator. I have read that some of the 1 wire regulators will work exactly like a 3 wire if you connect all three wires and some wont. Depends on the manufacturer. Maybe this is why there is no clear cut information.
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Old 03-15-2011, 08:13 PM
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I don't think Delco ever made an OEM alternator that was designed for 1 wire operation. If you have a real OEM Delco 10si or 12si alternator, or equivalent, it should always be a 3 wire. However, if you have a Delco that was converted to 1 wire it would have a self energizing regulator.

These links explain what regulator is used in a 1 wire alternator.

http://www.purplesagetradingpost.com...o/onewire.html
http://search.waiglobal.com/partnum.aspx?part=D10SE12

Bruce
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Old 03-16-2011, 07:31 AM
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Quote:
Originally Posted by T-bucket23
The main difference between a 1 wire and a 3 wire is the regulator. I have read that some of the 1 wire regulators will work exactly like a 3 wire if you connect all three wires and some wont. Depends on the manufacturer. Maybe this is why there is no clear cut information.
That is what I've seen as well. If you look at the two tabs for the connector that stick through the alternator housing, some one-wire units actually have these two tabs connected by a little metal bridge strap. Obviously, this won't work as a three wire unit. I have never seen an OEM one-wire unit, though some marine applications may be set up that way.
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Old 04-01-2012, 01:42 PM
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why would be practical to have only one wire to the alternator?

if for looks, the 3 wires can go inside a nice loom and would make no difference,

I have used one wire alternators and they need to be revved up to start charging, I don't like that much.

so why going one wire if 3 is fine?
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