JD 24volt charging

[CraigM]

I am restoring an old 5020. It has a 24 volt starter. The wiring was pretty hacked up when we got the tractor, so there's almost nothing to copy or start learning from. I have been able to learn that the 24v parts for the electrical system (starting and charging) are isolated from the tractor frame, that the interconnect between the 12v batteries is grounded, and the lights and conventional 12v stuff is split between the two 12v batteries. What I haven't been able to figure out is how they charge the batteries with a 12v alternator.

Can anyone help?

 

[beenthere]

Have you looked for a service tech manual for the 5020? Some schematics of the wiring should show what leads to what.

If not available, a visit to your Deere dealer to get such schematics should be a possibility too.

A quick google search turned this up:
John Deere Ag - New Equipment: Technical Publications - Publications Search

or

John Deere 5020 Dsl OEM Service Manual: John Deere Manuals: Amazon.com: Books

 

[CraigM]

It should be that simple. The dealer is a little tight lipped about giving out too much tech stuff. I have gotten some diagrams from them, but they are different than the ones in my manual even though they are the same TM-1022 manual. I hesitate to buy another manual, especially at $100+.

 

[MORRISONSTEEL]

By now the bulk of the split system tractors have been converted to all 12v. Your biggest expense is a 12v starter, after that pretty minimal parts needs. There used to be a kit for 4010's, early 3020's etc but not aware of one ever for the 5020, probably because it already had an alternator. Can't really blame the local dealer for not stepping out every step that needs to be taken though in the greatest of detail, its how they make a living.

 

[beenthere]

You be close enough to Corporate at Moline, and I'd wander in there Monday morning and bum around with a few of the top dogs. Don't think they would throw you out if a visitor and would expect they would dig up some info at least to decide if there are different manuals out there.
Dealers are being combined now into large multi-dealer enterprises and want every minute accounted for on a ticket charged to a customer. Unfortunate, but the way it is happening. Don't know if that is your dealer's demise... yet.

 

[MORRISONSTEEL]

Any version of this tech manual will have the same information regarding the theory of operation, which should be enough to repair. That said, I still recommend converting the tractor. There will be gobs of aftermarket alternatives for a 12v starter and they will be heckufa lot cheaper than any 24v starter if you ever need to replace. Then you have simplified the "theory" by a bunch. Only thing to watch for when purchasing a starter esp if looking at a gear reduction is to verify there is enough room for the taller height. Good luck

 

[jd110]

If your tractor serial number is under 25000, It should have a 24 volt starter and a 24 volt charging system. It could have had a generator or alternator depending on exact serial number. If it is serial number 25000 or above, it should have a 12 starter and alternator.

 

[CraigM]

The tractor is under s/n 25000. Has a 24v starter, but the alternator says delco 12v negative on it. The alternator has 2 output terminals on the back that are both isolated from the frame. There are also 2 flat faston type terminals in the side of the alternator. For voltage to power the regulator and field? Do you have anything on how to connect the fastons or how to charge a pair of 12v batteries in series? I haven't opened the alternator up to confirm that the regulator is 12v. If it had been modified to 24v, that would make it all simple. The wiring diagrams I have show 3 terminals on the alternator, so this is probably not the original alternator. Still, the original alternator is listed as 12v, so there is that persistent problem of how did they charge 24v of batteries with a 12v alternator?

 

[Tx Jim]

There is no way to my knowledge that a 12 volt alt. can be utilized on a 24 volt system. All I think you'll see is smoke.

 

[pmsmechanic]

These tractors charged with a 12 volt alternator because the alternator or generator has two separate 12 volt terminals. One for each battery. The battery's are isolated from each other so then it works. The battery's are connected in series for starting. I don't understand how it all works and they whole setup is an interesting bit of engineering that works as long as you don't pull too much power from one battery as there is only one voltage regulator.

As long as you keep all your light's working and don't add something to one battery like a monitor for a round baler for example then the load is pretty even on both battery's and one voltage regulator can do the job. The whole system is a bear to figure out and most people just switch to a 12 volt system as it's not hard to do and it's easier to understand.