(800) 853-2651
SHOP NOW

Alternator question

N

notjustair

Well-known Member
My Farmall M is 12 volt. It has a Delco three wire alternator on it. I have it set up with a multiple pole toggle on/off switch to excite.

During the summer it works just as it normally should. Charges about 10 amps and then backs off. During the winter it is squirrelly. If it is below freezing it doesn't charge when I first start it. I start going about my chores and about 5 minutes later it starts charging normally. It is like it has to warm up first. It doesn't matter whether I give it a larger load (I just chored and turned on the lights right when I started it). If I shut it down and then start it again it works normally. It isn't like it needs more throttle to get it started - that doesn't make a difference. It got a new battery a while back - that wasn't it either. The only variable that could be causing it is temp. I have eliminated all other variables.

I have put Delco units on several other tractors around here and they don't do it. What would need to warm up in there to make it charge? It's got me puzzled. I expect it and it is just fine like it is, but I always wonder about it.
 
I had the switch as it was in the cheap rack at the hardware store. The others I use an idiot light. I like how it works - it was less to mess with.
 
Nutter reason to ditch that useless amp meter and install a volt meter... BTW if you can double flare steel tubing I can help you add a oil switch so it will excite with oil pressure...
 
Cold belt equals less fiction and less fiction means more likely to slip. As for your switch I have a set up on one machine that you have to turn on the head lights to excite the alternator. Did it because I did not have a diode on hand at the time
 
I would agree, check the fan belt. I have "fixed" several non charging M generators / alternators by tightning the fan belt. An M will run cool with the fan hardly turning, much to slow to make a generator / alternator work.

Have also seen a few worn or sticky alt brush sets that would not make contact when cold.
 
They make a resister that bolts on the back of the alternator so you don't need a switch. An idiot light does the same thing as the resistor. Actually they're both resistors but the light glows when current flows thru it.
 
What this resistor does is it allows enough current from the ignition switch to flow thru the alternator to excite it. But once the alternator starts charging it back feeds current thru this resistor to the ignition switch but this resistor cuts the current down low enough so when you turn the ignition switch off the engine will shut off. With out the resistor enough current would be back fed up to the ignition switch to feed the ignition circuit and not let the engine shut off.

Best way to wire in this wire to excite the alternator is to wire it to the accessory terminal on the ignition switch not the ignition terminal. You won't need a diode, idiot light or resistor then.
 
Stepfather was a mopar mech so I learned to carry a spare resister. I picked up a dual element resister so I always knew where to find the spare :)
 
John, have you ever tried a diode? I use 3 Amp 1000 PIV units, why are WAY over-rated, but don't fail. $.99 and up (shipped) on ebay. (#321024828925)
 
You must log in or register to reply here.

Similar threads

R
Alternator Confusion, Positive Ground
2
Replies
29
Views
2K
used red MN
U
R
Alternator question
Replies
16
Views
489
RodinNS
R
grandpa Love
Alternator issues fixed
2
Replies
23
Views
2K
JOCCO
J
C
Ford 8N question
Replies
12
Views
621
Fixingfarmer
Fixingfarmer
M
Electronic ignition questions.
Replies
12
Views
596
buickanddeere
B
Tractor Parts Tractor Manuals

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Copyright © 1997-2024 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy

Back
Top