Polarity

[JeffaH20]

Why did manufacturers produce positive ground systems and negative ground systems. Is it because of the 6volt/12volt or some other benefit. Maybe no reason at all. Help please.

 

[old]

Part of it was they way they believe electrons flowed years ago, but they have changed there minds on that one so they switched it to - ground.
Hobby farm

 

[Jerry Coulter]

Don't know. Back about 1950, GMC came 6v+ and Chevrolet trucks came 6v-. We sold GMC and there were mechanics around who were everlastingly putting new batteries in GMCs backward.

 

[Anonymous-0]

I wonder if there is any truth to the story I once heard,that early battery powered telegraph / telephone systems had less corrosion of the ground rods when the battery was connected positive ground.
The story was that because of this, pos ground was considered 'correct" for any battery power system, even though tractor / car electrical systems had no connection to ground.

 

[Coloken]

While I realy don't know, I think that there is some basis for this.

This question comes up about every 3 months here.

 

[Allan in NE]

Absolutely no reason whatsoever.

Allan

 

[Anonymous-0]

Back in the hayday of electric trolleys, the side grounded affected underground metal water and gas pipes. Electrolysis would eat holes in some pipes. So the polarity that added metal to the pipe was used. Trouble is the pipes at a distance needed the opposite polarity of pipes close to the power plant. Whichever pipe owner yelled the loudest got the preferred polarity.

In vehicular batteries, there has been the postive negative argument that lasted from the first ones until a mixture of alternators and solid state radios came out, and even for a while solid state radios (both AM/FM and two way) were made with a switchable polarity to work with either side of the DC system grounded. Before that tube type two way radios had polarity switch provisions for decades. Eventually, SAE, I think, decided the various arguments were poorer than the consistency of one universal ground polarity and so decreed negative ground.

Fact is, either polarity works and always has. And if the wiring design is going to use the frame and major castings for one side of the circuit, there just has to be that choice of polarity made. In the 30s automotive engineers argued at length for one or the other, some makes were positive ground, some were negative ground. I have forgotten their arguments, but I think the main one was about corrosion of connections at the frame.

Besides which, when we learned current was electron flow and by convention electrons have a negative charge, all our polarities are backwards anyway. We can blame that inversion on Ben Franklin. He had two choices and guessed wrong.

In another way, positive and negative are simply mathematical concepts arbitrarily applied to electric polarity. Either works, we just have to agree on which one to use so we can swap measurements. When we develop the freedom to work with either polarity, we are no longer bothered about one or the other and I had to develop that freedom going from designing vacuum tube circuits to germanium transistor circuits, then switch back for silicon transistor circuits. Now I don't care which way is up, the numbers all come out and the circuits work so long as the power and the circuit polarity match.

I used to have a book by B.G. Lamme with a collection of articles and I think it may have had one on the automotive polarity arguments.

There were many more options on the choice of frequency for AC systems and settling on only a couple frequencie world wide (neglecting trolleys) took half a century of discussion.

Gerald J.

 

[Drill]

Some of the early British equipment used positive ground (or earth as they called it). Why, same reason they drive on the "other" side of the road. No one knows.

 

[John T]

From what Ive gathered prior to Neg ground becoming the industry standard, Ford N Chrysler n some others believed there would be less corrosion where frame members were joined if the battery was attached with its Pos to frame ground i.e. the current flow through frame members back to the battery is what was at stake. Where I was an enginer we used to pass DC current a particular direction through buried metallic pipes to help reduce corrosion (cathodic protection)

John T

 

[Anonymous-0]

M y wife is Neg ground in fact she is neg all over.....

 

[KEB]

Same reason home video tape came in both VHS and Betamax formats. I've never been able to find a good technical reason for one way or the other; lots of opinions, some of which are listed below, but nothing definitive. Like VHS winning out over beta for no particular reason other than marketing, negative ground won out over positive ground.

Keith

 

[John T]

Maybe swap her wires sometimes when shes not lookin lol

John T

 

[John T]

Keith, I find a lot of people get too much all bent outa shape over this, I tell em a battery really dont care which post you hang a big hunk of iron onto and chassis grounding of EITHER battery terminal just allwos the use of tractor iron as a return current conductor so you dont have to run 2 wires to everything.

take care

John T

 

[Dan-IA]

I'm told neg. ground is planned obsolescence, as + ground tends to prevent rust. I have an old JD A that looks faded but not rusty. My other tractors have some rust.

 

[Anonymous-0]

When you move from standing to walking, which foot do you lead with? Whichever you start with, you define the following sequence of alternating feet.

Choice of battery polarity has about the same significance, just that the coil, generator polarity, and battery have to match. Different makers had different preferences for polarity and if you maintain those three parts, everything works.

Some claim that gas gauges in some JD are polarity sensitivity and work poorly on the wrong polarity. So far I believe changing the polarity on my gas 4020 the gas gauge problems were worn out sending unit, and with that fixed, it indicates reassonably well. Yes the calibration for empty is off, but I bent the float wire while working on the sensor. I haven't checked it a full because if I filled it, I'd have to mortgage it to pay for that much gasoline.

Gerald J.