12 volt alternator

[khouse6]

i have a older tractor, converted to 12 volts. alternator is a one wire , delco. is not charging. yesterday , i checked the wire and it seems to be correct, as far as i can determine.

local rebuild shop, advised, a few years ago, that alternators lose their excitement, as he phrased it. so he did his thing and i went out the door. is there something that i can do, without removing the alternator and carrying to repair shop.

perhaps John T will chime in here.

 

[22778]

DOES YOU ALTERNATOR HAVE 2 SMALL SPADES ON THE OUTER EDGE?

 

[Janicholson]

There is very little polarization involved in a one wire Delco 10SI alternator is most common. They have two spade connectors on the edge of the back frame. if so, it could have a rubber/plastic plug in the recessed hole. If so pry it out. The housing will have a "1" and a "2" cast into it near the hole. With a 1/4" female spade connector, attach a wire to the #2 terminal With it running, touch that wire to the positive battery post, or the ignition coil on the supply side. If it now charges, and continues to charge, you could hook it up as a 3 wire. By adding a diode with the band on the diode toward the alternator, and the connection to the ignition, or a marker lamp, or a 10 ohm resistor. Any of those will work to keep the engine from running when shut off with the key/switch.
If no joy, buy a new one or rebuilt to replace it. I don't like one wire alternators, but they do work. Always disconnect the battery when putting a one wire to sleep for more than a month. They keep drawing a small amount of electricity when the tractor is not running. The three wire does not. Jim

 

[Ken Hansen]

(quoted from post at 11:27:45 06/04/20) i have a older tractor, converted to 12 volts. alternator is a one wire , delco. is not charging. yesterday , i checked the wire and it seems to be correct, as far as i can determine.

local rebuild shop, advised, a few years ago, that alternators lose their excitement, as he phrased it. so he did his thing and i went out the door. is there something that i can do, without removing the alternator and carrying to repair shop.

perhaps John T will chime in here.

Here's a link to a video that may help:
https://www.youtube.com/watch?v=QPl7CTb685I


And here's a link to a tech tip from Delco:

http://www.delcoremy.com/the-latest/2013/march/tech-tip-flash-the-field

Either one should help explain it for you.

 

[old]

One of the problem with the 1 wires is what your having. I have a 1 wire on an 8N and it charges when it wants to and doesn't at other times. They also tend to need high RPM to self excite

 

[old]

Question
You say the #2 connector but isn't that the sense connector which tells the volt regulator when to turn off

 

[Janicholson]

#1 you are correct and I am wrong. Jim

 

[John T]

KH, Im better on 12 Volt DC gennys and such then I am on Alternators, Professor Jim is better on them. But FWIW unlike the iron field poles in a DC genny which CAN loose magnetic strength and polarity, an alternator doesn't work that way. With an alternator the field is the inner Rotor and when spinning it induces AC into the fixed outer Stator. The magnetic field in the inner Rotor is created via the slip rings passing current through the Rotors windings. UNLIKE a genny, it doesn't have big heavy soft iron field poles that retain some degree of magnetic field strength that requires polarization, excitation current through the rotor is what creates its strength. In the old 3 wire units the 1R small side spade terminal is where the initial excitation current enters to create the Rotors magnetic field strength until there's enough RPM that its now self excited.

Sorry I cant tell you how to fix it but some so called "one wire" units just have a black rubber plug over the 2 small 1R and 2F terminals and you might apply voltage to the small 1R and see what happens

If Im wrong (its happened lol) hopefully Professor Jim can enlighten me !!!!!!!!!!!


John T More of a Genny then an Alternator guy so noooooooooooooo warranty

 

[Janicholson]

Good to go John. Jim

 

[John T]

Yayyyyyyyyyyy thanks Jim. If I'm not mistaken I think they made a cheap so called three wire to one wire alternator conversion plug and all it did was have a high ohm resistor from 2F to 1R which provided a small amount of rotor excitation current for initial excitation but that would, of course, cause a constant small battery drain. But maybe I imagined that ???? lol

John T This is gettin above my pay grade

 

[old]

Guess maybe you had a senior moment? Was not trying to make you look bad by the way

 

[khouse6]

wow thanks

 

[khouse6]

thanks

 

[CenTex Farmall]

I have heard other people complain about the one wire alternators not kicking on until a higher RPM is reached. Some have to rev the engine up close to high idle to get the alternator to do its thing.

I use the regular 10si when I convert something. It only takes two wires to hook one up. I hook the #2 terminal right to the output on the alternator so I only have the big wire going to the battery and the #1 wire going to a switch. Done.

You can do as Jim says and use a diode to prevent backflow from the #1 so it won't keep powering the ignition when you want to shut down OR you can use a kill switch with two poles and have the ignition on one pole and the alternator on another.

In particular, The last couple of alternators I've brought home will power up and charge as soon as the tractor is running at idle.

Residual magnetism isn't a thing on alternators since the field is generated by applied voltage. What can lose magnetic field over time are magnetos and old ALNICO magnets on speakers.

 

[wore out]

(quoted from post at 16:21:29 06/04/20) I have heard other people complain about the one wire alternators not kicking on until a higher RPM is reached. Some have to rev the engine up close to high idle to get the alternator to do its thing.

I use the regular 10si when I convert something. It only takes two wires to hook one up. I hook the #2 terminal right to the output on the alternator so I only have the big wire going to the battery and the #1 wire going to a switch. Done.

You can do as Jim says and use a diode to prevent backflow from the #1 so it won't keep powering the ignition when you want to shut down OR you can use a kill switch with two poles and have the ignition on one pole and the alternator on another.

In particular, The last couple of alternators I've brought home will power up and charge as soon as the tractor is running at idle.

Residual magnetism isn't a thing on alternators since the field is generated by applied voltage. What can lose magnetic field over time are magnetos and old ALNICO magnets on speakers.

"Residual magnetism isn't a thing on alternators since the field is generated by applied voltage."

CenTex, how do you think "one wire" alternators build up rotating field voltage at startup to "excite"?

Some versions that excite at low RPM's use special low forward voltage drop diodes in the diode trio, and some use voltage regulators that turn on the field current (sourced from the output stud) when they detect rotor rotation.

And how is rotor rotation sensed, well, from the low voltage AC the stator puts out under influence of the residual magnetism in the rotor.

So at least SOME residual magnetism IS needed to get the charging process started in a "one-wire" alternator.

 

[old]

Many 1 wire alternators I have seen right in the instructions state VERY clearly 2000RPM need to excite so if the paper work say that who do I believed the paper or you

 

[CenTex Farmall]

I don't disagree with what you're saying.

I could have been more clear in my statement. In the original concept, GM was not relying on residual magnetism to make the thing
work. In an OE setup the residual magnetic field strength is moot.

 

[FBH44]

I have not read all these replies, so maybe someone has answered. But my H did the same thing, I bought a diode gizmo from Charlie U at From Charlie Uthke, Charlie's Repair, 22195 State Hwy 56, Austin, MN  55912 [email protected]. Installed it, and fixed! The Delco 10SI immediately goes into charge mode, tapers off, works perfectly. Very economical too. And I understand nothing about electrical systems.

 

[John T]

Yo CenTex I agree with your statement "GM was not relying on residual magnetism to make the thing work." While sure there's going to be some degree or residual magnetism in iron components around which current carrying wire was wrapped, in an Alternator it's not the same amount of residual magnetism as in the huge heavy soft iron field poles in a Generator. Even if there's some degree of residual magnetism in an Alternators Rotor and even if that's what gets initial excitation started, the primary cause of its magnetic field strength is due to the current that passes through the Rotors windings. The residual may get it started but its NOT enough for full blown output....

No warranty but I believe that's correct

John T Where you located?? my favorite daughter lives near Austin. We are allowed to visit there but since were not thirty something like most in the City, we cant stay too long lol

 

[khouse6]

not that i see, at the moment

 

[Janicholson]

I manage that OK by my self, and would never consider what you say as personal. Jim

 

[khouse6]

took alternator to shop. feller says, alternator is working.
hmmm

 

[old]

If it is the 1 wire you have to bring the RPM up high to self excite

 

[CenTex Farmall]

I am closer to Waco.

Austin started growing in the early 90's and I don't believe it has stopped yet! A very popular place.

 

[khouse6]

it is and it is a farmall 140. cannot get lots of RPMs