I have a 4010 diesel, been converted to 12-volt, one wire alternator, has two 12-volt batteries hooked parallel,575 cold cranking amps each. Would it be better to have two 6-volt batteries hook in series at 850 cold cranking amps. Current batteries will not hold a charge overnight; alternator is putting out 14.2 volts. Seems to me when I bought this tractor it didn't spin like it should, maybe the batteries were going south at that time. Has an aftermarket starter on it, could be part of the problem, I'll see if I can if Ican get a picture so somebody can tell me if it is the right one.