Pos or neg ground

earlgrimm · Feb 21, 2011

My 8N was converted to 12volt. But they left it Pos ground? Should I change it to neg ground? Anything to check or just turn the battery around?

Also battery cables. Any good supply and part Number?
Earl

old · Feb 21, 2011

Does it have a generator or alternator on it? If it is an alternator then you have to stay with how it is grounded or you will let the smoke out of it the moment you hook the battery up. But it is also not likely to be + ground with an alternator

Ultradog MN · Feb 21, 2011

If it starts and runs good why fix it?

KL-VA · Feb 21, 2011

Absolutely no way to tell what is right for your tractor without seeing what you have. Maybe with some really good photos, the electrical wizards could figure it out. There is no guarantee that your conversion was done anything like any other conversion. Even the battery cable question depends on the battery group size, type of terminals, and location of terminals on the actual battery you are using. Part numbers become meaningless when you are dealing with a conversion.

souNdguy · Feb 22, 2011

ditto what old said. positive ground alts are out there.. but rare.

what do you have.. alt or gen?

soundguy

earlgrimm · Feb 22, 2011

(quoted from post at 06:59:28 02/22/11) ditto what old said. positive ground alts are out there.. but rare.

what do you have.. alt or gen?

soundguy

I have a gen. What is the advantage of Neg ground?

Bruce (VA) · Feb 22, 2011

The debate went on for years as can be seen by the number of vehicles that were positive ground, then negative ground, then back again.

There seems to be (IMHO) a slight advantage to keeping a front distributor N positive ground because the coil polarity can not be changed. That being said, there are plenty of front distributor N's out there w/ alternators that are negative ground & they run just fine.

If the tractor is positive ground w/ a 12v generator & a frontmount, I'd leave it be. If it has a side distributor, make sure the coil is connected correctly (tip # 33). However, if you want to change the polarity, make sure you polarize the generator before you start it up. (tip # 23).

Lastly, one advantage to negative ground is that it could prevent the "electrically challenged" from polarity reversals that could explode a battery.
50 Tips

JMOR · Feb 22, 2011

(quoted from post at 10:59:09 02/22/11) The debate went on for years as can be seen by the number of vehicles that were positive ground, then negative ground, then back again.

There seems to be (IMHO) a slight advantage to keeping a front distributor N positive ground because the coil polarity can not be changed. That being said, there are plenty of front distributor N's out there w/ alternators that are negative ground & they run just fine.

If the tractor is positive ground w/ a 12v generator & a frontmount, I'd leave it be. If it has a side distributor, make sure the coil is connected correctly (tip # 33). However, if you want to change the polarity, make sure you polarize the generator before you start it up. (tip # 23).

Lastly, one advantage to negative ground is that it could prevent the "electrically challenged" from polarity reversals that could explode a battery.
50 Tips

ruce, you speak of auto makers switching back & forth & not being able to make up their minds.......well, I think John Deere with tractors such as 4010, 4020, & others just couldn't make up their minds at all, so they simply (or not so simply) used BOTH Positive Ground AND Negative Ground on the SAME tractor simultaneously! And that's the truth. :lol:

Dell (WA) · Feb 22, 2011

hey earl........didja know Henry Ford and Thomas Edison were great buddies???

Ol'Tom found out that positive ground made for longer lightbulb life and sparkplug life. Also Henry hated LAWYERS and ol'Boss Kettering had "patented" negative ground electrical starter scheme on the "Cadallac" and he used negative ground. And Henry did NOT like to pay patent rights, so positive ground.

But the real reason for 12V negative ground is the diodes in the alternator. It was physically eazier to manufacture diodes so the anodes were "heat-sink" to the frame of the alternator. Power handleing diodes must have a way to stay cool or they will "melt".

Gennys can be either positive or negative ground because they use "mechancal" switches (armature and brushes) to change alternating current to direct current. Diodes are a 1-way switch that is used to convert alterating current to direct current. And in this case, alternator internal solid-state diodes DEMAND NEGATIVE ground.

More better to ask why 6-volt??? 'cuz that was the smallest (cheapest) battery that Boss Kettering could find to turn the Cadallac electric starter motor so m'lady didn't need a "chauffeur" to drive her to town fer tea'n'crumpetts........Dell wants a biscotti, eh?

JMOR · Feb 22, 2011

(quoted from post at 14:08:56 02/22/11) hey earl........didja know Henry Ford and Thomas Edison were great buddies???

Ol'Tom found out that positive ground made for longer lightbulb life and sparkplug life. Also Henry hated LAWYERS and ol'Boss Kettering had "patented" negative ground electrical starter scheme on the "Cadallac" and he used negative ground. And Henry did NOT like to pay patent rights, so positive ground.

But the real reason for 12V negative ground is the diodes in the alternator. It was physically eazier to manufacture diodes so the anodes were "heat-sink" to the frame of the alternator. Power handleing diodes must have a way to stay cool or they will "melt".

Gennys can be either positive or negative ground because they use "mechancal" switches (armature and brushes) to change alternating current to direct current. Diodes are a 1-way switch that is used to convert alterating current to direct current. And in this case, alternator internal solid-state diodes DEMAND NEGATIVE ground.

More better to ask why 6-volt??? 'cuz that was the smallest (cheapest) battery that Boss Kettering could find to turn the Cadallac electric starter motor so m'lady didn't need a "chauffeur" to drive her to town fer tea'n'crumpetts........Dell wants a biscotti, eh?

Dell, now , we all know that you are a 'good-ol-boy', but sometimes I (we) have to wonder where you get your information! Cadillac was Positive ground until 1946, & got first electric starter in 1912. You won't be able to produce one iota of evidence that a light bulb will last longer, positive gnded, negative gnded, or not grounded at all. "...solid-state diodes DEMAND NEGATIVE ground. ". Horse pucky!! Open up a Delco 10DN sometime. There are 6 diodes....half (3) are pressed into the case (ground) and those are ANODE-to-case AND the other half are cathode to case and are pressed into an insulated aluminum heat sink. The maker even made the printed markings on them RED (cathode to case) or BLACK (anode to case), so duffuses could tell a cathode-to case diode from an anode-to-case device. simple eh? Further more, swap the blacks & reds and wallah! Now you have a Positive ground alternator which has a Negative output. Regulating it is another subject. And I won't address the "why 6v battery", because unlike some folks, I don't speak authoritatively about matters that I do not KNOW about.

tractorfix · Feb 22, 2011

I just modified a 10SI to positive ground for a 50 8N. You can buy the rectifier for 15bucks on eBay. The only caveat is that there are no pos grd regulators so you have to wire it up correctly to work right. I did it because of the coil polarity, although I've done them neg grd lots of time with no ill effect. I guess its just a "so I can say I did it" thing.

KL-VA · Feb 22, 2011

JMOR hit the nail. Converting GM 10-SI alternators to 6 volt positive ground is easy. You just buy the positive ground bridge rectifier instead of the negative ground bridge rectifier. I have a diagram saved somewhere that shows which screws get insulated and where to install an insulated jumper. When you are done you now have a one wire, positive ground, internally-regulated alternator. Of course, I'm thoroughly baffled why anyone would WANT one. It's too darn easy to let the magic smoke out of an alternator to confuse things by making one that's positive ground. Somebody is sure to toast it unless you stick 6 inch labels on everything.

JMOR · Feb 23, 2011

(quoted from post at 19:06:06 02/22/11) JMOR hit the nail. Converting GM 10-SI alternators to 6 volt positive ground is easy. You just buy the positive ground bridge rectifier instead of the negative ground bridge rectifier. I have a diagram saved somewhere that shows which screws get insulated and where to install an insulated jumper. When you are done you now have a one wire, positive ground, internally-regulated alternator. Of course, I'm thoroughly baffled why anyone would WANT one. It's too darn easy to let the magic smoke out of an alternator to confuse things by making one that's positive ground. Somebody is sure to toast it unless you stick 6 inch labels on everything.

ep, 99.44% of people walking up to a tractor with a Delco alt hanging off the side will jump to conclusion/assume that it is NEGATIVE ground....& be right about that same % of time.

Pos or neg ground

earlgrimm

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old

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Ultradog MN

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KL-VA

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souNdguy

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earlgrimm

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Bruce (VA)

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JMOR

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Dell (WA)

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