Positive ground or negative ground?

[Clay L]

Originally Posted by TQ60

The reason for positive ground is related to how magic happens at the atomic level and I can not remember specifics this morning.

Telephone systems are all positive ground and transmission sites are variable as most 48 volt sites are positive ground but 25 volt ones depend on manufacturer.

There may have been some old truck equipment that was positive ground but my memory of the old oddballs were some that had a weird starting system that had 2 batteries that starter selenoid would series to 24 volt for starting and we had to be real carefully hooking up the radios but that was a long time ago...

Back in the 70s as I recall, White Trucks still used positive ground. The Chief Engineer at White was a campaigner for positive ground and published a paper claiming that it reduced corrosion. I probably still have the paper packed away in my engineering records somewhere.

[frankdamp]

Positive ground was used on most British motorcycles on into the 1970s. The last ones were the mid-1970s Norton Commandos, just before Norton-Villiers shrank to its present role as parts supplier for the old bikes.

I left N-V in mid-1968 to join Boeing. The shrinkage was just beginning then after the Norton product line was moved from Birmingham to London. The new Norton company in the UK has no connection to the old one, except it still calls its bike the "Commando". They've added "961" in the name to denote its engine size.

[mccsix]

Here is a negative ground car, 1928 Model A...........

[rgvtexan]

[QUOTE=Gary RVRoamer;2643534]I don't think any vehicle has used a positive ground in the last 60 years. I'm sure there is an exception somewhere (there always is), but nothing you are likely to ever encounter./QUOTE]

Just a SHORT 48 years ago, my 67 MGB-GT had positive ground.
We will probably never see it again.

[Ray,IN]

Ya'all might find this thread interesting: Cadillac explains why they used positive ground for so long.

[bthomforde]

In 1975 I bought a new White Road Commander semi truck, I didn't realize it was positive ground until I hooked my 8 track up and it "ate" the tape as in ran backwards.
It was always fun trying to get somebody to jump start it, they didn't want to blow up their batteries or charging system.

[chboone]

I remember Ford used Positive ground at least till the late 50's, and maybe later.

[sirpurrcival]

So just out of curiosity, wouldn't a positive ground car give you bit of tingle if you happened to be in bare feet and touched something metal?

[stink]

Originally Posted by sirpurrcival

So just out of curiosity, wouldn't a positive ground car give you bit of tingle if you happened to be in bare feet and touched something metal?

Nope! A bit of electrical theory/fact, electrical flow is electrons moving from a negatively charged item,aria (neg post of battery) to a positively charged aria, item (pos post on battery). Electrons do not like each other just like similar poles on a magnet repel each other. Electrons are negatively charged particles (very small) and are always trying to get away from each other and get to a positively charged item,aria. A positive charge is just a lack of a negative charge.
With a positive ground car there is no electrons available to give tingle and some beleive (britts) that a neg ground system has electrons on the surface of the charged item (car) promotes corrosion. So,,, yup electricity flows from neg to positive!

[eaglestar]

Originally Posted by chboone

I remember Ford used Positive ground at least till the late 50's, and maybe later.

Ford used 6V positive ground through the 1955 model year. In 1956 they changed to 12V negative ground. My first car was a 1955 Mainline with a fried 6 cyl engine. I replaced the engine with a 1956 V8 I was given. Rather than try to retro the ignition and charging system I upgraded the chassis to the 12V neg, mostly just bulb changes (I think I just had to change out the radio and gauges, too many years gone by to remember clearly). Everything ran great until I blew a main bearing, but that's a tale for another time and another forum.

Ray

[Gary RVRoamer]

Ford used 6V positive ground through the 1955 model year.

That's what I was thinking of when I mentioned "the last 60 years". My old 48 Dodge coupe had a positive ground too.

Just a SHORT 48 years ago, my 67 MGB-GT had positive ground

LOL, I should have guessed something like that. MG (and Lucas electrics) was always 20 years behind the times. Even my 1960 Fiat Spyder was "advanced technology" in comparison!

[t55watson]

If ya liked to mess with old tractors you would soon learn about Positive ground. Most are wired that way.

[JRNOLL]

For those that have had Lucas electrical systems know that "Lucas was the prince of darkness. Or the reason the Brits drank warm drinks was that "Lucas made their refrigerators". I have owned 3 different 60s British autos.

[Gary RVRoamer]

The tech literature says that negative vs positive ground is a tradeoff of where you are willing to suffer some background galvanic corrosion. Back in the day that was a concern, but in modern vehicle design that has been largely eliminated. If they were to do it all over again today, the choice might be positive ground rather than negative, but there is so little difference pro or con that it's not worth changing an established manufacturing standard.