12 volt conversion. The smart choice. Done on my 1966 4020 D. No regrets. 24 volts for cranking only....Batteries have come a long way in improvements.
 
(quoted from post at 17:00:42 05/15/18) What happened to the 24 Volt questions and comments? Formerly, there were a couple every week.

We got 'em all fixed!

Got three of 'em in my life, and they work with not many more issues than any other tractors their age.
 
There are a lot of misconceptions about the system. The foremost is that there are two 12 volt systems for the lights one positive ground and one negative ground. If you think about it just a little, the batteries have little to do when the tractor is running. The GENERATOR is supplying the power and voltage and current out the generator can't be flowing both ways at the same time! The lights are in series with 12 volts dropped in the first light and the remaining 12 volts dropped in the second light. To make it easier to visualize, imagine no batteries and just the generator powering the two lights. Thinking of it this way, it would be absurd for current to be flowing both ways at once. There is more to the system than this but this concept of one series circuit is fundamental to understanding the system. This explanation of the system should bring some of the pundits and "experts" out of hibernation. I hope this helps.
 

erskine2017
You're ""stirring the POT"' so here goes.

I don't know if you refer to me as a pundit or "expert" & I really could care LESS but way back about 40 yrs I've experienced a lot of ""hands on 24 volt experience"".

You state JD 24 volt system headlamps will operate without a ground connection by current flowing through both headlamps please explain what takes place when light switch is turned to "D"(dim) & only 1 headlamp on each fender is burning? Also I remember way back in the 60's-80's seeing 12 volt headlamps that wouldn't illuminate & were black on the inside my guess is this black look was caused by too much voltage being applied to headlamp. Where did this excess voltage come from? What's your opinion on what caused "black inside" headlamps?

If no chassis ground for lights is required where does flashing(warning) lamp(key 19) which has a 12 volt bulb get it's 12 VOLTS?????

mvphoto16638.png
 
The reason I believe (for no questions) is the system is actually simple for most so there's no need for questions here on the board. The majority (NOT all) of the fine gents here understand it...........

As JOHN DEERE Wiring Diagrams and JOHN DEERE Publications and JOHN DEERE Service Bulletins plainly show and how JOHN DEERE built them, its really ONLY a TWO WIRE 24 volt FLOATING (NOT Pos Ground as one person here has claimed) system AS FAR AS the Starter and Charging System are concerned, and two 12 volt banks (One POS Ground other NEG Ground) for 12 Volt loads.

With the center series (of two 12 volt banks) tie point bonded to frame/ground, one 12 volt bank is POSITIVE GROUNDED with respect to the center tie point, while the other is 12 volts NEGATIVE GROUNDED with respect to the center tie point to frame/ground. NOTE it can also be a wire used for current return instead of the frame like on some later model tractors but still its two 12 volt circuits fed off the A or B feed (One Neg other Pos) to the switch !!!!!!!!!!

Then two A & B feeds (One POS ground other NEG ground w/ respect to center series tie point) are ran up to the light switch SO SOME LIGHTS ARE WIRED TO THE NEG GROUNDED BATTERY (Via A feed to switch) WHILE OTHERS ARE WIRED TO THE POS GROUNDED BATTERY (via B feed to switch) to balance loads among the two batteries ITS REALLY QUITE SIMPLE YALLLLLLLL !!!!!!!!!!!!!



DONT TAKE MY WORD FOR IT READ WHAT JOHN DEERE HAD TO SAY ABOUT IN THEIR OFFICIAL PUBLICATION !!!


John Deere Service Bulletin # 268 August 1958

"The electrical system used on John Deere Diesel ( E l e c t r i c Cranking) Tractors is a 24-volt split-load system using 24 volts for the cranking and charging circuits and 12-volt circuits for the lighting and accessory load. Figure 41A is a schematic draw--ing of the system A 24-volt generator, controlled by a 24-volt regulator, supplies current to carry the electrical load and charge the four 6-volt batteries connected in series which supply current at 24 volts for cranking the engine.

The cranking circuit and the charging circuit are two-wire circuits- the entire circuit is carried through wires and no part of it is grounded to the tractor frame.

Two 12-volt circuits are obtained by installing a ground wire between the second and third batteries in the circuit and the tractor frame. Also, the combination switch is in reality two separate switches enclosed in a single housing and operated by a single lever. One of these switches controls current to approximately ll2 of the load, the current being supplied by two of the batteries. The other switch controls current to the remaining L 12 of the load, current being supplied by the two remaining batteries.""


JOHN DEERE built them that way,,,,,,,,JOHN DEERE described the system in THEIR Official Publications,,,,,,,,,,,,,JOHN DEERE wiring diagrams showed them that way,,,,,,,,,,,,,,The system WORKS,,,,,,,,,,,This is DC not AC current, current flows in one direction at one time WELL DUH

NOTE the Batteries supply energy to power lights and 12 Volt loads, The Charging System charges the batteries WELL DUH


SOOOOOOOOOOO if anyone believes the above isn't correct take it up with JOHN DEERE not me, tell them how they were built and diagrams show is incorrect but YOU ARE CORRECT LOL LOL These are THEIR WORDS and how THEY were built and how wiring diagrams show THEY were built and how official publications describe THEIR operation.

My advise is to believe JOHN DEERE and the "go to guys" on this Forum as far the 24 volt system is concerned such as Tx Jim and Bob and Buick (gave 24 volt seminar at Two Cylinder Expo), dont take my word for it TAKE A LOOK AT WHAT JOHN DEERE SAYS AND PUBLISHED

If anyone doesn't understand how JOHN DEERE Deere built them and how JOHN DEERE described them and how JOHN DEERE explained them in JOHN DEERE publications (and they work remember) do some research and study and post back any questions BUT AGAIN THE REASON THERES NO MORE QUESTIONS is its really not all that hard to understand it for anyone with basic DC circuit knowledge..

Believe John Deere not meeeeeeeeeeeee lol

Best wishes and God Bless all here, hope this helps

John T Retired Electrical Engineer
 
Every one with BASIC DC electronics understands the system so no need for questions. I just started a friend's 730 that had sat all winter and the batteries (still has four 6Vs) were down. Used a battery pack that has its own built in jumper cables (quite a neat rig) that is capable of 12V or 24V and the tractor fired right up. Charging system is working good at about 27 Volts output.

Retired EE here too!
 
Retired EE's and Techs and Electricians ROCK !!!!!!!!!!!! Yeppers DC circuits 101 was the first and by far easiest course to master Freshman year. It was AC circuits and Solid State Physics and Maxwells Equations and Electromagnetic Field Theory that got complicated, so glad those old Deere's didn't use all that stuff lol

Take care Ron

John T
 
Tx Jim, On bright with dual headlamps 24 volts come from battery A, through the light switch and feeds 24 volts to a headlight on each side of the tractor. 12 volts are lost or dropped in these bulbs. Current now flows from the base of the lights, through the metal of the fenders and enders the other pair of lights through the base of the lights and the remaining 12 volts are lost here. Current flows out the wire of the lights and back through the light switch to Battery B. 12 volts are lost in one pair of lights and the remaining 12 in the other pair since it is a series circuit. If the switch is on dim current flows from a pair of lights like before, but this time it returns to battery B through the rear light and warning light. If every thing is balanced there is little current in the middle wire. If the middle wire is broken, the fuel gauge and dash won't work. However they will when you turn the lights on! Burned out bulbs have several causes. This is explained in detail in my three articles in "Green magazine."
 
I see you are pontificating again. You should move to Italy and run for Pope. I hope you know more about the law than you know about series-parallel circuits. Are you sure you didn't skip class the day they were explained. A high school physics student would know that a generator can't charge negative and positive at the same time!
 
Thanks for the bulletin John, it makes everything crystal clear. I've never really got into the 24 volt discussions, not really knowing much about them, but now that I know the starting and charging are isolated circuits, everything falls into place. A lightbulb moment, if you will, lol!

Cheers,
Lyndon
 
(quoted from post at 15:17:57 05/17/18) Tx Jim, On bright with dual headlamps 24 volts come from battery A, through the light switch and feeds 24 volts to a headlight on each side of the tractor. 12 volts are lost or dropped in these bulbs. Current now flows from the base of the lights, through the metal of the fenders and enders the other pair of lights through the base of the lights and the remaining 12 volts are lost here. Current flows out the wire of the lights and back through the light switch to Battery B. 12 volts are lost in one pair of lights and the remaining 12 in the other pair since it is a series circuit. If the switch is on dim current flows from a pair of lights like before, but this time it returns to battery B through the rear light and warning light. If every thing is balanced there is little current in the middle wire. If the middle wire is broken, the fuel gauge and dash won't work. However they will when you turn the lights on! Burned out bulbs have several causes. This is explained in detail in my three articles in "Green magazine."

You must be smoking something other than tobacco. I don't have access to Green Magazine plus I have more important things to do than read your undocumented ideas. How does 24V travel from left fender to right fender without a wired connection? Then you have the audacity to state on dim continuity travels from frt lamps to rear lamp & warning light.

You never attempted to explain how warning light(flashing) gets it 12 VOLTS!!!!!!!!! It must have been explained in 1 of your 3 articles in GM.
Jim
 
You're most welcome Lyndon. Glad it makes all "crystal clear" And as I noted THATS HOW JOHN DEERE BUILT THEM AND THEIR WIRING DIAGRAMS AND THEIR SERVICE BULLETINS EXPLAINS THE WORKINGS OF THE 24 VOLT SYSTEM NOTTTTTTTTTTTTTTTT ME.

You can choose to believe John Deere and/or me who as an Electrical Engineer,,,,,,,,,,As a used tractor dealer,,,,,,,,,,,,,, And one who farmed with those tractors found them to be orrrrrrrrrrrrrrrrr someone who has no understanding whatsoever of basic DC circuits 101

In my humble opinion if you chose to believe John Deere you made a wise choice

John T
 
With all due respect to a dear old friend and as an Electrical Engineer and a past tractor dealer and one who farmed with and worked on those tractors I BELIEVE JOHN DEERE (and Tx Jim and Buick (who gave an informative 24 volt seminar at Two Cylinder Expo) and others who agree with John Deere as I described above) INSTEAD OF YOU, A RETIRED HISTORY PROFESSOR, but that don't make you a bad person and unlike you I will not make personal attacks or resort to name calling but will take the high ground and hope you can understand that system someday like most of the rest of us do already. I'm more then willing to help you out NO PROBLEM my old friend !!!!!!!!!!!

I consider you a friend and kind old gentleman Tom, so don't take it bad that I agree with John Deere instead of you. The John Deere wiring diagrams and service bulletins were the same as I found them to be !!!!!!!!!!!!! They show one 12 volt bank as POS Ground and the other as NEG Ground and each feeding the A & B circuits up to the light switch to balance the 12 volt lighting loads THATS JUST HOW IT WORKS TOM regardless if you believe it or not, sorry..........

I hope all is well with you and your family, God Bless you.

Sincerely,

John T
 
Tx Jim, you seem like a real nice guy and I appreciate your kind remarks. Unfortunately, my cat knows more about 24 Volts and basic electricity than you!
 
(quoted from post at 20:46:15 05/17/18) Tx Jim, you seem like a real nice guy and I appreciate your kind remarks. Unfortunately, my cat knows more about 24 Volts and basic electricity than you!

Well if your cat understands the JD 24 volt system so well maybe you can talk your cat into answering the questions I asked you to answer BUT since you didn't answer my questions it appears you must not know the answers so maybe your feline will help you.
 
erskine2017 I have been sitting on the sidelines watching the show. You seem to be an educated man but, please tell us all how many years of hands on experience you you have with these systems. Myself and several other posters here spent time in a JD service shop and we worked on these systems. We trouble shoot them and fix them. Some like the system and others hate the 24v system. No matter how many words you type you can't take real world experience and knowledge away from us. I don't call myself an expert on these systems or anything I fix. As soon as a man claims to be the expert he is quickly humbled. You should except your flaws and not come onto this forum looking for trouble.
 

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