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.

 

[Tx Jim]

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

.

JD had no 24 volt system charged with a 12 volt alternator as you describe. Maybe some other company but not JOHN DEERE!!!!! There is a 12 volt alt listed in 5020 parts catalog # 978 sn< -024,999 but this is how the footnote reads (A) 24-VOLT TO 12-VOLT START/CHARGE CONVERSION KIT

 

[pmsmechanic]

JD had no 24 volt system charged with a 12 volt alternator as you describe. Maybe some other company but not JOHN DEERE!!!!! There is a 12 volt alt listed in 5020 parts catalog # 978 sn< -024,999 but this is how the footnote reads (A) 24-VOLT TO 12-VOLT START/CHARGE CONVERSION KIT

So at first I was going to hotly contest this as I was sure that I was right. Then you started me thinking and I went and pored through my books to see if I was right or not. The books I have (I&T manuals) didn't really give a whole lot of details but it did show me that one battery is charged on the + terminal and the other is charged on the - terminal suggesting two separate charging circuits of 12 volts each.

So I waited till my favourite electrical repair shop was open and I phoned him and asked whether the 3020,4020,5020 had a 24 volt generator on a 24 volt system. He told me the same thing I told you guys. It's a 12 volt generator with two separate charging circuits. One for each battery. I quote "The only thing on those tractors that is 24 volts is the starter and part of the dash depending on the serial number break".

Now as far as the John Deere conversion kit goes yes you would have to change both the starter and the generator if you are converting to 12 volts. The generator for a 24 volt system is different that one for a 12 volt system because of the two separate charging circuits in the 12 volt generator for a 24 volt system.

Now my buddy did look it up in his parts books and he told me that there were only two different generators available for John Deere 24 volt systems. I'm not 100% sure on this but if the tractor has a factory alternator then it should have a 12 volt starter. The only exception to this would be if someone has installed an alternator and a series/parallel switch so that they can still use a 24 volt starter. A series/parallel switch is a heavy duty solenoid which changes battery connections to serial for starting and leaves the connections parallel the rest of the time. John Deere's do not come from the factory with a series/parallel switch so if your tractor has one it's been added by a previous owner.

 

[Tx Jim]

So I waited till my favourite electrical repair shop was open and I phoned him and asked whether the 3020,4020,5020 had a 24 volt generator on a 24 volt system. He told me the same thing I told you guys. It's a 12 volt generator with two separate charging circuits. One for each battery. I quote "The only thing on those tractors that is 24 volts is the starter and part of the dash depending on the serial number break".

As I previously stated JD 24 volt system didn't come from the factory with a 12 volt generator or alternator no matter what your "favorite electrical repair shop person" stated!!!!!!!! I was employed by a JD dealer in parts,repair & sales from '66-'87 and I know what I state is FACT. The starter,generator or alternator & regulator is isolated from the tractor frame IE NO GROUND connection.

 

[pmsmechanic]

As I previously stated JD 24 volt system didn't come from the factory with a 12 volt generator or alternator no matter what your "favorite electrical repair shop person" stated!!!!!!!! I was employed by a JD dealer in parts,repair & sales from '66-'87 and I know what I state is FACT. The starter,generator or alternator & regulator is isolated from the tractor frame IE NO GROUND connection.

So I talked with a John Deere service tech this morning. His words are that both the battery's are charged in parallel and the starter draws the current in series. That's what the wiring diagrams that I have show too. So you aren't going to charge a 12 volt battery with 24 volts, therefor the generator is 12 volts unless you want to add up the two outputs and say it's 24 volts.

All I know is that if you want to repair the system you need to understand it. The generator has two separate 12 volt charging circuits in it. Both are controlled by one voltage regulator. If you add a load to one battery like a radio, or a fan for the cab, or a monitor for a round baler sooner or later you are going to have one dead battery. It was definatly an ingenious engineer that developed the system. What he forgot about was that over time a burnt out light bulb, some extra resistance somewhere, or accessory's would change the way the battery's needed to be charged. That's why John Deere came up with a change over kit. I just buy the starter and do the rest myself as the John Deere kits are pricey. A 12 volt 3020 starter on eBay used to be around the $200 mark.

Tx Jim I don't really want to get into a big argument with you. If You want to stay with the idea that everything you say is fact go ahead. Maybe John Deere built tractors differently for the Texas market. There are lots of things I don't know, but i do have a basic understanding of how a John Deere 24 starting system works. Thanks to you I now understand it better that I did before.

 

[Tx Jim]

pmsmechanic
The JD tech you talked to this AM needs to attend a 24 volt seminar as JD 24 volt system batteries are charged in series not in parallel. Texas 24 volt tractors rolled off the same assembly line in Waterloo,Ia as the rest of the world. I'll bet you CAN"T provide this forum with a John Deere part number for this phantom 12 volt alternator with 2 separate posts designed to independently charge two 12 volt batteries on a 24 volt system on a JD 3020/4020 or 5020. Maybe you can get the JD tech you talked to this AM to provide you with this phantom part number for alternator you refer to?? Plus very few JD 24 volt system tractors rolled of the assembly line with alternators as they had generators. IIRC the only tractors with alternators had cabs with AC. IIRC JD did have a unique 24 volt system on some industrial equip that I have zero experience on because I was employed by an "ag only" dealership.

Back when I was the JD service manager for over 10 yrs I diagnosed many problems on JD 24 volt systems on the 10 & 20 series rowcrop tractors so this ain't my 1st Rodeo.
Jim

 

[MH8675309]

I had a 4010 and it had a 24 volt system. They were noted for sometimes having electrical fires related to that system. Its about $1000 to pay someone to switch it over to 12 volt. The tractor was a 1961 model.

 

[Tx Jim]

JD had a field install circuit breaker kit to help alleviate the fires you referred to. A JD 24 volt system can be changed from 24 volts to 12 volts by installing a 12 volt starter & alt for less than $500. On wiring all one needs to do is connect circuit A & B(brown & blue) wires to top post on 12 volt starter solenoid and wire up a Delco alternator. I can't remember exactly which fuel gauge & sender one needs.

 

[buickanddeere]

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?

Some wild tinkerer has removed the 24V generator which floats electrically isolated from the chassis and probably jammed on a 12V neg chassis alternator?
It maybe time to entertain a 12V conversion using the mighty Delco 44MT. It's a PM gear reduction starter that will wail an engine over like few starter can.
Lots of warm weather uses install a 4KW nipper but there is a 5Kw nipper that turns a 531 cu better .

 

[buickanddeere]

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?

Ain't so

 

[buickanddeere]

So at first I was going to hotly contest this as I was sure that I was right. Then you started me thinking and I went and pored through my books to see if I was right or not. The books I have (I&T manuals) didn't really give a whole lot of details but it did show me that one battery is charged on the + terminal and the other is charged on the - terminal suggesting two separate charging circuits of 12 volts each.

So I waited till my favourite electrical repair shop was open and I phoned him and asked whether the 3020,4020,5020 had a 24 volt generator on a 24 volt system. He told me the same thing I told you guys. It's a 12 volt generator with two separate charging circuits. One for each battery. I quote "The only thing on those tractors that is 24 volts is the starter and part of the dash depending on the serial number break".

Now as far as the John Deere conversion kit goes yes you would have to change both the starter and the generator if you are converting to 12 volts. The generator for a 24 volt system is different that one for a 12 volt system because of the two separate charging circuits in the 12 volt generator for a 24 volt system.

Now my buddy did look it up in his parts books and he told me that there were only two different generators available for John Deere 24 volt systems. I'm not 100% sure on this but if the tractor has a factory alternator then it should have a 12 volt starter. The only exception to this would be if someone has installed an alternator and a series/parallel switch so that they can still use a 24 volt starter. A series/parallel switch is a heavy duty solenoid which changes battery connections to serial for starting and leaves the connections parallel the rest of the time. John Deere's do not come from the factory with a series/parallel switch so if your tractor has one it's been added by a previous owner.

Nope, ain't so