6V Positive ground system

[Mrbill]

Question to the group please. I believe I have a 6V positive ground system on a project tractor I picked up (my first ). It had a newer 6V battery, but I was getting nothing from it. I checked it and it shows 6V after a charge, but it shows -6V. I took it to the auto parts store, and they confirmed. He said the battery was bad. If I hook it direct to the starter, it will turn a couple of times slowly, then stops. So wanting to confirm 6V+ system? Do I need to replace with a specific type of 6V battery? (the one in the tractor had 700 CCA). I have a 12V lying around, can I use that to see if I can get the thing running and/or starter turning? Or will I mess something up? Thank you in advance for your help!

[tst]

yes that is a 6 volt positive ground, 1 start with making sure all your battery and connections are clean and tight, then if it still has a problem look at the switch on the starter, the contact inside can go bad

[ricky racer]

I suggest not using the 12v battery. It will save you from fixing things later. If the battery is truly bad, replace it with a group 1 6v battery. Rural King has the best pricing around here.

[staninlowerAL]

If the battery tested NG then you need to get a good 6v battery like Ricky said. Once you get that solved and all the connections bright shiny clean and tight (remember that the starter grounds through the frame of the tractor), if the starter turns over slowly (or not at all) get your starter tested. Your starter could be in need of a rebuild. Your coil in the pictures might need a better ground than the strap tied with a piece of wire. JMHO

[Jim Becker]

You said the battery shows -6 volts. Are you saying it is charged backwards? If so, that may be why the parts store declared it bad. If that is the case, completely discharge it by hooking a light to it until it is completely dead. Then recharge it the correct way. It may recover. In the other hand, it may not.

[halftonstude]

if a battery is reversed long enough to hold a charge in the reverse direction considerable damage has been done to the plates and active material. the plates are generally pure lead or a lead calcium alloy (to make the plates stiffer and stronger) and the chemistry after charging is pretty different: positive grids are lead dioxide and negatives are pure lead. The reversing of the charge will convert much/some of the positive to pure lead and some/much of the negatives to lead dioxide which will cause the plates to change shape and the little pouches of active material (picture the plates looking like a waffle and the active material being the butter smeared into the holes) will not only lose contact with the grids, but some will/may fall out to the bottom and pile up, which is sediment that can foster short circuits between plates later on. reversed cells can recover if they were only reversed for a short amount of time and didn't stay there long. Just in case anybody was wondering... if the red lead of the meter is plugged into the + hole on the meter, and touching the + post of the battery, and if the black lead of the meter is plugged into the - hole on the meter, and touching the - post of the battery, and if the meter shows -6.xx, the battery is reversed. ground connection to the tractor is only a reference and will not influence what the meter indicates - the meter merely reads magnitude. Direction (+ or -) is determined by the location of the leads. Location and placement of the ground cable of the tractor is what determines whether the electrical system is +6v or -6v... or positive or negative ground. Connect the + post of the battery to the frame of the tractor you have positive ground. Ground isn't necessarily earth. The NEC defines ground pretty well: either earth, or a body that serves in place of the earth like the chassis of a vehicle. hope that helps.
c

[Eugene]

12 volt battery will easily power a 6 volt starter without damage and start the tractor. You will need to add a ballist resistor, Chrysler ballist resistor from auto parts store, to the coil for continued operation.

Use the 12 volt battery to conduct compression tests. Ignition off. No need to start the tractor for compression tests.

[halftonstude]

many old hot rodders keep the 6 volt starters with their flathead engines. gives a great spin for fast starting. the starter is engaged so little there's not really a chance of overheating the windings.