Farmall M charging issue - must rev engine for charge

[KentS]

Hello, i have a 47 Farmall M that has a 12V AC Delco alternator conversion on it. the alternator tested bad a while back so i put a new one on it.
when i start the tractor, the amp meter shows discharge unless i rev the engine way up. then it will kick in and charge the whole time i'm using it.
when i shut it off, same thing again every time i use it.
seems like this shouldnt be necessary. would appreciate any thoughts you have. it has the internal regulator like 1980's GM type products. thank you ! Kent

 

[Nebraska Kirk]

One wire or three wire alternator?

The one wire alternator on my M needs the engine to rev up to start it charging

 

[mac rusty red 1010]

This is common on 12 volt conversions especially with the one wire set up. There are smaller o.d. pulleys, 60 mm rather than 80 mm available just for this issue.

 

[Bob M]

Hello, i have a 47 Farmall M that has a 12V AC Delco alternator conversion on it. the alternator tested bad a while back so i put a new one on it.
when i start the tractor, the amp meter shows discharge unless i rev the engine way up. then it will kick in and charge the whole time i'm using it.
when i shut it off, same thing again every time i use it.
seems like this shouldnt be necessary. would appreciate any thoughts you have. it has the internal regulator like 1980's GM type products. thank you ! Kent

Pretty much normal with the Delco 10SI (internally regulator) alternator - both the one wire and 3 wire versions.

Either live with it, or replace the alternator sheave with a smaller one to spin it faster.

 

[Brownie450]

We had trouble with the 10SI 3-wire on the 1066 after the mechanic
didn't reattach the wire to the #1 R terminal up by the inst. panel.
I made a 2" wire that is stripped on both ends, & shaped into a U.
After the engine is running, momentarily touch the wire to the output
[hot 12 Volts--battery] & the #1 terminal. If you get the wrong terminal
on the alternator, it won't matter since #2 is the battery sensing term.
Jim

 

[old]

Hello, i have a 47 Farmall M that has a 12V AC Delco alternator conversion on it. the alternator tested bad a while back so i put a new one on it.
when i start the tractor, the amp meter shows discharge unless i rev the engine way up. then it will kick in and charge the whole time i'm using it.
when i shut it off, same thing again every time i use it.
seems like this shouldnt be necessary. would appreciate any thoughts you have. it has the internal regulator like 1980's GM type products. thank you ! Kent

Is it a true Delco 10SI with 3 wires or is it a modified Delco 10SI one wire. If a one wire that is the problem they have and need high RPM to self excite. If it is a 3 wire if it needs high RPM to excite you have either a bad alternator of it is wired wrong

 

[Janicholson]

You can pronably put a clearance light bulb (incandescent, not LED) in series with the ignition switch (coil side) and the #1 terminal and have it start earlier. Jim

 

[Bob in wc Ia.]

The Tractor Doctor had a good article about how to fix this problem in the March-April 2018 issue of Red Power Magazine.
I haven't tried it myself. It's a simple short wire assembly with a diode he ordered from Tisco at the time. Looks like the company
is called SMA now. The part # is 6X10301D.

 

[BarnyardEngineering]

Frankly I wouldn't even consider it a problem. Our M has been like that for somewhere between 35 and 40 years. One-wire alternator. Just goose the throttle, and it starts charging. If you forget, it starts charging the first time you rev it up anyway. Not like the battery is going to go flat dead in 30 seconds, or 30 minutes for that matter.

 

[KentS]

thanks everyone. it is indeed a 1 wire alternator and that makes perfect since. my WD45 has a 3 wire alternator and i dont have that issue. i think i will live with it for now, i just wanted to understand why it didnt excite until revved up.

appreciate the responses !!!!!!

 

[Ellis Kinney]

I have three Farmall M tractors converted. They all do that and I don't even consider it a problem. I always wait until the tractor is slightly warmed up and goose the throttle once and problem solved. Ellis

 

[old]

thanks everyone. it is indeed a 1 wire alternator and that makes perfect since. my WD45 has a 3 wire alternator and i dont have that issue. i think i will live with it for now, i just wanted to understand why it didnt excite until revved up.

appreciate the responses !!!!!!

By the way a 1 wire alternator can also cause a slow discharge of a battery over time

 

[Turkeyfoot]

My 49 uses a one wire. It also still has a magneto and it starts on the first crank. So as long as that one-wire comes on every now and then to charge the battery for the next start, it's not an issue.