John Deere 2640 Delco Alternator Conversion

[DWalker2640]

Ive been working on converting my 2640 from the Motorola style alternator to a Delco one wire (self exciting) alternator. Ive got everything mounted up, and tried it today and the alternator is only putting out 12.5-12.6 volts at the alternator. I reused the factory battery hook ups for the Motorola style alternator. Im wondering if I need to run a wire directly from the alternator to the battery, so the alternator will sense the voltage drop on the battery, instead of going to the starter like the factory. Im sure one on here has run into this before.

 

[wore out]

(quoted from post at 14:54:13 03/10/22) Ive been working on converting my 2640 from the Motorola style alternator to a Delco one wire (self exciting) alternator. Ive got everything mounted up, and tried it today and the alternator is only putting out 12.5-12.6 volts at the alternator. I reused the factory battery hook ups for the Motorola style alternator. Im wondering if I need to run a wire directly from the alternator to the battery, so the alternator will sense the voltage drop on the battery, instead of going to the starter like the factory. Im sure one on here has run into this before.

"Im wondering if I need to run a wire directly from the alternator to the battery, so the alternator will sense the voltage drop on the battery, instead of going to the starter like the factory."

No. It should work just fine as it was originally ASSUMING there's not a failed connection in the original wiring.

(You could have just as well used a "three wire" alternator and connected the lead from the powered dashboard indicator lamp to the alternator's #1 terminal and jumpering the alternator's #2 terminal to it's 9large) output stud.)

 

[DWalker2640]

The wiring should be good, I put all new wiring harness in it 3-4 years
ago (Deere sourced). Im puzzled why its only putting out 12.5-12.6
volts. It doesnt charge the battery at that rate, learned that the hard
way today, and the output stays the same regardless of the engine
RPM. I wonder if I need a smaller pulley to spin the alternator faster?

 

[Jim.ME]

Could be you got a bad alternator. It happens.

Just to confirm the alternator you got has a plug blocking access to the two spade terminals in the side, correct? If there is no plug, I would suspect it is a three wire alternator.

 

[Jim.ME]

As far as needing a smaller pulley. It doesn't need a smaller pulley to charge. A smaller pulley will spin it faster and it will start charging sooner, but if it hasn't started charging at 1/2 to 3/4 throttle, it's not a pulley problem in my mind.

 

[DWalker2640]

Yes it has the rubber/neoprene cover over the terminals.

 

[Jim.ME]

Assuming your wiring is correct, I would lean towards a bad alternator. If you just bought it I would say take it back.

If it is one you had you could remove the rubber plug and use a jumper wire to put power to the #1 terminal (terminals have been there on the ones I've had), and see if it charges.

Here is a Delco Remy Tech tip sheet.

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

 

[cannonball]

you probably have a external voltage regulator..try jumping a wire to battery and post on alternator ...on my 2840 the motor has to be moved to full throttle and after it is it will charge at any throttle..

 

[DWalker2640]

Ill check and see if those are still there. I had the alternator rebuilt
prior to putting it on the tractor, and told them I wanted the self
exciting style, but it may need that wiring hooked to the No. 1
terminal to make it kick on.

 

[J.Wondergem]

I had one that I converted over to self start. It wouldn't work, had to change it back to three wire.

 

[miangus]

Not sure why you would want a one wire on that vintage of tractor. Wouldn't it work best to use the Delco with the internal regulator and run it through your light? Everybody else seems to have good luck with the one wire alternators, I have not, after going through one alternator and a regulator on my Farmall 400, I installed a standard three wire regulator and a light. It's not a fancy light in the dash like you would have but it works fine.