Ok thanks guys! RScotty, let me make sure I understand you. If I hook up the cables like you said. Pos to the rh side front terminal and neg to the frame it will charge both batteries? And I can do this with a 12 volt charger right?
Yes, but there are some "ifs" to check first. JD used several different systems back then. That's when many manufacturers were changing from six to twelve volts, from generators to alternators, and away from specialized "floating" dual battery diesel starting systems.
So best to check these things:
1. BTW, I'm assuming that yours is a gas tractor - NOT a diesel - and also that you really do have two six volt batteries like you think. If you do have a diesel, they had an unusual dual battery system and we had better start over.
2. You said that you think it has two six volt batteries hooked in series. That makes sense...it was a common way to make 12 volts at a time when 12 volt batteries were not as common. But I want to double check that we are right. Look at the vent caps on one of your batteries. Six volt batteries have three caps; twelve volt batts have 6 caps per battery. Also, how are the batteries connected together?
3.Check what the frame polarity is on your tractor. If the frame is negative that means that one of your batteries will have it's negative terminal connected directly to the frame. The stock frame connection was an large flat braided cable about an inch wide and a quarter inch thick...and it did not have any insulation on the cable, it was just a big flat bare braided cable. If yours still has that flat braided cable going to the frame...check which battery terminal that cable is connected to.
Take a look and we'll get this system right for you.
If it is gasser.....and those really are six volt batts in series....and the negative terminal of one of the batteries is connected to the frame then connect the 12 volt charger just as you say.
luck, rScotty