positive ground

[tuney443]

Just noticed the previous owner has the battery polarity backwards on my newly aquired 440ICD.I see it's supposed to be positive ground.What damage do you think was done?

[CELSESSER]

Does it have the original generator on it or has it been converted to a GM alternator? If it has an alternator on it then it has been changed to negative ground. There have been a number of posts in the past on that conversion and what needs to be changed.
I don't know what effect it would have on a generator setup.

Chuck

[Stan Disbrow]

Hi,

The generator can be polarized either way. If he had it neg gnd, and you go pos gnd, then you'll have to repolarize the generator. He might also have reversed the ammeter wires, if he didn't like it reading Discharge when it was Charging after the polarity swap.

Later!

Stan

[JD440ICD2006]

I read where someone somewhere back then thought that running the electrons back wards resulted in less corrosion. Not sure if it was more than just a bad perception.
The alternator will care, but a generator will not, as long as you polarize it before start up once you have changed it.

[jdemaris]

I read where someone somewhere back then thought that running the electrons back wards resulted in less corrosion. Not sure if it was more than just a bad perception.
The alternator will care, but a generator will not, as long as you polarize it before start up once you have changed it.

A generator doesn't care as it can be polarized either way. Some mechanical regulators do care however. If the reg. is marked for a particular ground - that's the only way it will work. Many are marked for both pos. and neg.

In regard to corrosion - no way is better overall than the other. Some types of corrosion in certain applications are exceptions. The reason why some cars and tractors had or have positive or negative ground is this. There are two competing theories of the flow of electicity - the Electron Theory and the Hole Theory. None have been proven and both are still valid. 50-100 years ago - different engineering schools had different preferences - just like Chevy and Ford owners, Deere and IH, etc. Engineers from colleges that adhered to the Hole Theory tended to make systems with positive ground. Engineers who favored the Electron Theory worked with negative ground. No system is better or worse. But . . . when semiconductors e.g. diodes, transistors, etc. came into common useage - a standard had to be picked for general use - and that was/is negative ground.

[Lavoy]

I had read a rather lengthy deal on why they thought that positve ground would result in less corrosion back then. Don't remember where I read it, it was a while back. I think a couple of electrical engineers were discussing as well, seems to me the general concensus was that the benefit was minimal if at all.
Lavoy

[jdemaris]

I had read a rather lengthy deal on why they thought that positve ground would result in less corrosion back then.

Positive ground is still used in certain specific applications to prevent special types of corrosion - mostly in military and marine equipment. In general useage - it's a crap shoot and there is no overall gain one way or the other.

[Stan Disbrow]

Hi,

Back when positive ground was selected in these things, there *was* an electro-migration issue with the points contacts themselves. Essentially, if you positively grounded the system, there was less migration of metal from one point contact to another than with negative ground.

As time went by, the issue became better understood and the metalurgy changed and so it mattered not which way things were polarized. This was all before WWII.

After the war, everything could well have changed over to negative ground, but someone somewhere decided not to bother with changing what was with 6v systems, probably to avoid confusion. 12v systems were negative ground, and eventually 6v died out, and the problem solved itself.

As far as electron flow vs. hole flow goes, that was all proven by the time I got into electrical engineering school. Basically, for simple R/L/C (resistor, coil, capacitor) circuits it's all electron flow - which is all we're going to see on this sort of equipment. Even vacuum tubes operate on electron flow. For most semiconductors, though, it's hole flow. Not that this matters one whit when talking about crawlers! Not unless we're talking about the 'hole flow' of the dirt off the blade, that is!

Later!

Stan

[jdemaris]

Hi,

Back when positive ground was selected in these things, there *was* an electro-migration issue with the points contacts themselves. Essentially, if you positively grounded the system, there was less migration of metal from one point contact to another than with negative ground.

Neither choice of ground polarity elimated metal transfer. A few older ignition systems used both - i.e. they either switched polarity back and forth as they ran automatically - or some used a manual polarity switch - often found in Atwater Kent and some Delco automotive ignition systems.

[hunter41mag]

Here is my 2 cents on this subject. I have been around farm machinery for most my life and in the trucking side for 33 years. I have always noticed there was less electrical connection corrosion with positive ground systems than negative ground systems even when both types were operated side by side in the same environment. The information I read on this (do not remember where) is that with a negative ground electrons have the ground circuit energized and with a positive ground system they do not. If the ground side would be all insulated cables there would not be any difference but since we use metal parts as part of the ground circuit (frame, brackets, engine block, etc) that are not insulated is where it creates some difference. Not allot but some.

Also with todays newer maintenance free batteries you do not see as much battery terminal corrosion as we did in the past with full maintenance type that vented gases and caused more corrosion. Unless its a hot day and the battery temp gets to high. This happened on my 2004 JD 4310 compact tractor last year and I did not catch it in time and the corrosion ruined my oil cooler. Leave it to mother Deere to mount the battery up against the oil cooler which is in front of the radiator and fan. The fan pulled the vented gases right back into the oil cooler core and till I saw it the oil cooler had a big solid section of corrosion. I have a new cooler but am not going to put it in until I get a new gel mat type battery for it.

[JD4302010]

Hi,


After the war, everything could well have changed over to negative ground, but someone somewhere decided not to bother with changing what was with 6v systems, probably to avoid confusion. 12v systems were negative ground, and eventually 6v died out, and the problem solved itself.


Later!

Stan

The positive ground application did not die out with th 6V system. JD used positive ground for many years in the New Generation 12V and 24V tractors.

[jdemaris]

The positive ground application did not die out with th 6V system. JD used positive ground for many years in the New Generation 12V and 24V tractors.

True enough. Neither ground system is any better then the other overall. The adoption of negative ground had to be adopted as a standard after the use of modern semiconductors - especially diodes, and transistors. In regard to Deere, they never made a tractor with an alternator that used positive groun

There are still some electrical systems with postive ground AND modern electronics - but the components are specialty items and very expensive.

[Lavoy]

I believe Deere quit positive ground in 69 when the side console tractors came out.
Lavoy