John deere

They used a split 12 volt system 12 volt positive ground for the armature, if I recall correctly and 12 volt negative ground for the fields, they also split the lights to keep the voltage balanced. Some positive ground and some negative.

I'm thinking one bad battery could do this, pretty sure the solenoid is one or the other because of the split electrical.

 

It wasn't a good way to do it, in 1969 they used 2 six volts in series, possibly the 5020 still used 4 six volts in series parallel.

I switched a 3010 diesel to 12 volt when the starter went, had a starter off a newer one that I had rebuilt and put on a Delco alternator, just simple, really, as long as you could come up with a 12 volt starter.

 

The ones with the pony motors had less electrical problems.

A neighbor had a 730 diesel, electric start, it smoked like a steam engine when it was pulling hard.

The 830 had the same engine run at higher rpm, again if i recall correctly, and got better fuel economy by horsepower hours per gallon. He had one of those later on and I drove it for an afternoon. It was different.

 

I found something about the John Deere 24 volt electrical system on petcare.net.

I know, very funny. It explained it pretty well. It's pretty long to read and has diagrams. Those systems worked well until they didn't and few knew how to fix them.

One thing I do remember is it takes much more capacity in the wiring and components, the 24 volt starter was much lighter in weight than the 12 volt Delco.