24 Volt Confusion

Joe Mindy

Member
Lately there have been some 24 Volt questions. There seems to be a tremendous amount of confusion concerning this system.

1) To POLARIZE, momentarily jumper between BAT and GEN at the regulator. If the regulator is inaccessible, jumper between the big terminal on the starter solenoid to the A1 terminal on the generator. Do this with the tractor not running.
Do NOT use a stick to close the cutout relay as one person suggested.

2) If the tractor does not charge, Jumper between FLD on the generator to A2 on the generator with the tractor running. As an alternate you can jumper between FLD on the regulator and GRD on the regulator. NOTE, the 24 Volt regulator has a ground terminal as it is isolated from the tractor frame as is the starter and generator. If the tractor now charges, the problem is most likely the regulator. If still no charge, the generator itself needs more testing. This procedure is known as FULL FIELDING the generator.

3) The small wire between the batteries has ABSOLUTELY no effect on the GEN light. If you don't use the lights or worry about the fuel gauge, the middle wire can be removed with no effect.
 

What is wrong with a stick to operate the cutout? It's fail safe to get the correct terminals.
What polarity is the 24V system?
 
You state "There seems to be a tremendous amount of confusion concerning this system"

I AGREE

Its really not that difficult if you understand it and have a grasp on basic DC circuits. Unfortunately, many of those confused persons you speak of have a hard time with it. I highly recommend people get and read John Deere Service Bulletin 268 from which I copied and pasted the info I pasted below.

Best wishes and Merry Christmas

John T
 
(quoted from post at 14:43:02 12/12/14)

3) The small wire between the batteries has ABSOLUTELY no effect on the GEN light. If you don't use the lights or worry about the fuel gauge, the middle wire can be removed with no effect.

Joe
Welcome to YT.

I guess you've never seen the headlights turned black & burn out the filaments from getting 24 volts instead of 12 volts?? Also the engine oil pressure light will not function properly without the wire in question.
 
"If you don't use the lights or worry about the fuel gauge, the middle wire can be removed with no effect. "

I DO NOT recommend removing that wire nor am I aware John Deere ever recommended it. I've seen weird things take place when its not present. But hey a person is free to remove that or any wire on his own tractor as he pleases...You were sure right, there is indeed a ton of confusion out there, it may not have been Mother Deere's best moment lol

Merry Christmas to everyone

John T
 
You're right Tech 7, but I think its just as the poster noted, there is indeed a lot of confusion out there and its probably impossible to stop all that in a few sentences posted here. A good study of SB 268 would sure help the gents.

John T
 
(quoted from post at 00:47:24 12/13/14) Have you ever done it? Did the points stick together like I said they would? How did you get them apart?

Of course they open. They are the same spring loaded HD silver plated contacts that the main generator output passes through.
 
Confusion?? Yeah. Like which 24 volt Deere system are you trying to discuss? The split Delco-designed system e.g.used in some 3020s/4020s? The series-parallel system e.g. used in some 1010 diesels? Deere used at least 4 different 24 volt systems. Some very different and some with subtle differences.
 
Stop and think of what is happening. When you close the points the flow in the big windings is opposite the flow in the pull-in windings so they tend to cancel each other. Maybe the spring will open them. But you have the fields and armature energized & when the points open without a condenser it puts a strong jolt to the pull-in windings which are not insulated for that high a voltage. In a 24 volt system I would not want to be touching anything when that jolt hits. It may fry the cut-in windings too.
 
I worked on a 3020 diesel that was having problems I never did figure out. I wired in a circuit breaker in that ground wire & it corrected it. Never did understand why.
 
(quoted from post at 21:18:29 12/13/14) Stop and think of what is happening. When you close the points the flow in the big windings is opposite the flow in the pull-in windings so they tend to cancel each other. Maybe the spring will open them. But you have the fields and armature energized & when the points open without a condenser it puts a strong jolt to the pull-in windings which are not insulated for that high a voltage. In a 24 volt system I would not want to be touching anything when that jolt hits. It may fry the cut-in windings too.

Teddy26

Pull up the wiring diagram and tell me how an external jumper runs current through the armature and fields in any different direction. Than using a a piece of wood or plastic to momentary close the main cut out contact?
The momentary closing of the cut out contacts eliminates any chance of bubba jumping the wrong terminals.
 

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