John Deere 5020

[Bill from Scotland]

So I haven't had the 5020 out in 14 years. Tried fitting batteries today 2 12v in series but when I touch the linking
cable they just flash. What am I doing wrong? Am I correct in saying they are 24v (alternator stamped 24v) and the their
is no earth (ground) in the syatem. Any thoughts welcome.

 

[WTW]

Tractor is / was originally a split 24 volt system. 12 + 12 = 24 volt Connect battery cross over Positive to Negative. If it arch's when connecting you have a short to ground somewhere. Either line can be shorted to frame?? To determine which line is shorted just connect one cable to one battery and temporally ground that battery to frame it should not draw current if all switches are shut off. Once you find which side is shorted, and get it corrected, you will then connect a frame ground wire between the two batteries / cross over to individualize each battery for the 12 volt circuits on tractor. Starting and charging is 24 volt no ground to frame. Lighting and instrumentation is 12 volt half on one Positive ground battery and half on the other Negative ground battery. Not as complicated as some people like to make it! DW

 

[Bill from Scotland]

I understand your logic. I just shorted out each battery to the frame but nothing showed up. As soon as I try to link the batteries I get an arch, in actual fact it would easily melt the battery polls. Could there be an issue with the starter solenoid in that its drawing power to starter? Any thoughts welcome.

 

[buickanddeere]

(quoted from post at 12:33:22 05/07/21) I understand your logic. I just shorted out each battery to the frame but nothing showed up. As soon as I try to link the batteries I get an arch, in actual fact it would easily melt the battery polls. Could there be an issue with the starter solenoid in that its drawing power to starter? Any thoughts welcome.

Try one battery at a time to check the +12V system and then the -12V system independently . To check if half the lights and half the instruments function on their own without sparks .

 

[WTW]

Remove cables from starter but keep wiring connected to cable ends. If still shorted the short is still in chassis wiring If not sorted short is in starter motor. You can also disconnect the two live lines at alternator to rule out short in alternator. DW

 

[SVcummins]

The one cable on the starter side is a ground not hot

 

[buickanddeere]

24V starter has one 12V battery always connected directly to and energizing the windings but no current flow unless there is a fault .
The 2nd battery is connected to the starter solenoid .
The regulator is wired in a similar manner to the starter .
Bad things will happen if the regulator body is not floating isolated from chassis on its rubber bushings .
For the typical user . Best to place the 24V components safely away in a well labelled box . And install a 12V system .

 

[Tx Jim]

(quoted from post at 16:06:16 05/08/21) The one cable on the starter side is a ground not hot

JD 24 volt electrical systems components such as the starter,gen & regulator are isolated/insulated from tractor frame with ""NO ground"".
Ground(+/-) is utilized to spit 24 volts for 12 volt lights/accessories