Delco Alternator

I have a Delco Alternator on my C and it works great. I got a kit on Ebay years ago and I rebuilt it myself and it was easy to do. I do not understand the differences with a 1 wire and a 2 wire model. All the kits I see on Ebay now are for a 1 wire model and mine is a 2 wire. Are the voltage regulator and diodes and brush holder the same on both models?
I once heard that the 1 wire model did not kick in until the engine was like 2000 rpm. My 2 wire works at once. Why would anyone want the 1 wire model over the 2 wire model? Can someone educate me on these!

(quoted from post at 01:58:11 10/10/19) I have a Delco Alternator on my C and it works great. I got a kit on Ebay years ago and I rebuilt it myself and it was easy to do. I do not understand the differences with a 1 wire and a 2 wire model. All the kits I see on Ebay now are for a 1 wire model and mine is a 2 wire. Are the voltage regulator and diodes and brush holder the same on both models?
I once heard that the 1 wire model did not kick in until the engine was like 2000 rpm. My 2 wire works at once. Why would anyone want the 1 wire model over the 2 wire model? Can someone educate me on these!

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I guess it's just personal preference. I've wired them both ways. The second wire serves to excite the regulator. On a 1-wire, you use a self-exciting regulator. The speed needed to excite would be dependent on the pulley diameters. With the stock 2 1/2" pulley it wouldn't take much more than a whack on the gas and it would start charging. With a 5" pulley you would have to rev it up a lot more. The biggest downside I've noticed with the self-exciting type is they don't seem to last as long and you usually have to order them on the internet.

(quoted from post at 17:58:11 10/09/19) I have a Delco Alternator on my C and it works great. I got a kit on Ebay years ago and I rebuilt it myself and it was easy to do. I do not understand the differences with a 1 wire and a 2 wire model. All the kits I see on Ebay now are for a 1 wire model and mine is a 2 wire. Are the voltage regulator and diodes and brush holder the same on both models?
I once heard that the 1 wire model did not kick in until the engine was like 2000 rpm. My 2 wire works at once. Why would anyone want the 1 wire model over the 2 wire model? Can someone educate me on these!

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Nothing wrong with wanting to use a 3-wire system, so long as you know how to wire it up. (And lots of good reasons!)

Some don't know how and will never figure it out no matter how much help they get, MANY MANY threads in the archives will back this up, a "one-wire" alternator is a blessing for those. And even then, they ask "how go a wire up a "one-wire" alternator"!

As to the 10SI and 12SI Delcos used in factory setups, virtually ALL were 3-wire.

A (rare) one-wire version was supposedly sold, but I have not been able to have anyone tell me a single application they were used on, "from the factory". If anyone knows of such an application, let's hear about it!

A 3 wire is a factory made alternator made by delco. A one wire has been modified to work but is not done as it was made to be done by delco. No such thing as a 2 wire since if one wires it up as a 2 wire the sense wire is not hooked up so it does not know when to stop charging so can/will over charge

(quoted from post at 06:13:28 10/10/19) A 3 wire is a factory made alternator made by delco. A one wire has been modified to work but is not done as it was made to be done by delco. No such thing as a 2 wire since if one wires it up as a 2 wire the sense wire is not hooked up so it does not know when to stop charging so can/will over charge

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A two-wire is just a 3-wire where they put the jumper either inside the case or just outside the case. If you follow the three wires in a factory setup you'll see that two of them merge together a few feet away from the alternator. I've always wondered why they do it that way, figuring an automotive electrician would probably know.

Maybe I do not understand the difference of 1,2,3 wire alternators. I assume they all use the large terminal output as one of the these wires. The wire marked #1 in my case goes to a diode and on to coil with 12v continuous. The #2 wire goes directly to the alternator output stud with 12 volts continuous. I think that is my present hook up, does that sound right?
I still do not know how the internal components differ in a 1 wire alternator and a 3 wire or 2 wire alternator. That is, are the voltage regulators and diode rectifiers inside the case the same? The reason I ask is that repair kits on Ebay all refer to a 1 wire alternator! Will these kits have the right parts for a 3 wire alternator?

(quoted from post at 17:21:26 10/10/19) Maybe I do not understand the difference of 1,2,3 wire alternators. I assume they all use the large terminal output as one of the these wires. The wire marked #1 in my case goes to a diode and on to coil with 12v continuous. The #2 wire goes directly to the alternator output stud with 12 volts continuous. I think that is my present hook up, does that sound right?
I still do not know how the internal components differ in a 1 wire alternator and a 3 wire or 2 wire alternator. That is, are the voltage regulators and diode rectifiers inside the case the same? The reason I ask is that repair kits on Ebay all refer to a 1 wire alternator! Will these kits have the right parts for a 3 wire alternator?

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If you are using classic view, you might not see that I have answered your questions. Or, I suppose you may not believe me. Either way, it's time for me to move on.

Wayne, what you describe is commonly referred to as a 3-wire alternator. BAT, #1, and #2... three wires.

A 1 wire alternator only has a BAT connection, and a special self-exciting regulator. The 1 wire repair kit would convert a 3 wire alternator into a 1 wire.

One wire: Is internally connected to the Output terminal so the sense connection is made. It also has an internal connection to that terminal that feeds a small amount of current to the regulator part. This causes it to use a few milliamps all the time (always on) so it begins to charge when the engine starts. The issue is that small draw can discharge the battery in a month or so of non use.

A 2 wire is not really a 2 wire, it is that the short wire from the #2 terminal is just not included in the count. (really a 3 wire because it is counted by me and most)

An automobile with electronic computers and controls needs accurate voltage control. All wires have loss. From the sense wire to the output stud fails to account for the loss in the main wire going to the battery through a fuseable link (this is car/truck stuff, where these were OEM) So in cars and trucks, the sense wire is not connected to the output stud, it is connected very near the battery to assess really accurately the charge voltage at the battery.

Us tractor fixers choose to shorten and simplify directly to the output stud.

A 3 wire uses a voltage supplied from the ignition to excite the alternator, thus preventing drain. The excite terminal operates like this: When the alternator is not turning, the #1 terminal appears to be grounded (regulator electronics) When the Ignition is turned on, but not started, There is voltage supplied to that terminal. If there was a light ulb in the circuit it would light up. With no light bulb, the voltage just excites the regulator to begin charging when it turns. _____But_____ when the alternator starts to charge, that #1 terminal goes to charging voltage, and with just a wire to the ignition, the alternator will feed charging voltage to the ignition coil keeping the engine running with the switch off.
That is the reason for the use of a small lightbulb, a diode, or a 10 ohm resistor. Each of those will supply excite voltage, but be a block to the current trying to keep it running with the switch off.

I hope I make sense, and have connected the ideas. Jim

Sorry to be late in getting back to you. I think I understand and would
have to convert to a 1 wire system if I rebuild it. Seems odd that there
would not be as many kits for 3 wire systems! Wonder why not! Thanks
for the info............

Thanks for the detailed info on these, I am sure lots of guys on this site are grateful for your help.
I read your post several times and think I understand it. I do not understand why all the repair kits on Ebay are for 1 wire systems when there are so many 3 wire systems in service!

The one wire is a bastardized Delco 10SI and made to work with only 1 wire which also can/will cause odd problem like having to bring up the RPM real high to make self excite but also so simple to wire up a 5 year old can do so

when they started making a one wire everyone was complaining about having to rev up the engine to get it to charge. I just put one on my 961 for. it shows charge at 900 rpm which is where I usually start the tractor. easy to install for sure. you will get both arguments of here but in reality either will work fine.

The kits are retail driven. The demand for one wire regulators and Kits are targeted toward those who choose simple over best. (arguable) Regulators and Diode packs for 3 wire are cheap and common. Bearings are commodity items. Thus knowledge drives the rebuilding of three wire alternators. Way cheap rebuilt, or cloned new alternators are about all that is in the supply chain. The last 3 wire I purchased from O'Reilly's charged and was at correct voltage before hooking up the #1 or #2 terminals. (A one wire in disguise) Hooking up the wires made no difference! Jim

(quoted from post at 15:10:47 10/10/19) Sorry to be late in getting back to you. I think I understand and would
have to convert to a 1 wire system if I rebuild it. Seems odd that there
would not be as many kits for 3 wire systems! Wonder why not! Thanks
for the info............

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"I understand and would have to convert to a 1 wire system if I rebuild it.

That's utter NONSENSE. Any part needed to rebuild your conventional 3-wire Delco is available on ebay and other 'net sources, as well as ANY autoparts store (if they have the knowledge to look them up and order them for you).

First off, you need to look beyond your notion that you need to buy a "kit", simply buy the parts you need individually, and look beyond fleabay, as well.

Here's 3 links to sites that will sell you any and all alternator parts you may need, and there's a zillion more out there!

https://www.dbelectrical.com/alternator-parts/

https://alternatorparts.com/

http://www.nationsautoelectric.com/altparts.html

"All the kits I see on Ebay now are for a 1 wire model and mine is a 2 wire."

I did a search for "Delco 10si kit" and within a couple pages came up with these 2 possibilities for 3 wire kit that you want.

131792679746

190857948768

I have already rebuilt the alternator using a kit I bought on Ebay over a year ago and don't know if the regulator is a 1 or3 wire model! I did not know there was a difference. I will put it on the tractor tomorrow and hope it works!
If the regulator is a 1 wire model, will I damage anything by plugging in the #1 and #2 wires? Could I just leave them disconnected and use it?
I can see why lots of folks would use a simple 1 wire model if all you have to do is connect the main bat lead to somewhere there is a 12v connection to charge the battery. Glad to learn that there is a battery drain with 1 wire models, thanks to you guys here on this site.
Thanks for all the info, I have learned a lot and found that rebuilding the unit is quite simple once you have the parts!

Wiring a one wire as a 3 only makes a difference if the factory put a plastic plug in the hole to keep you out. Wire it up. Jim