Question of + Ground

With all the threads concerning systems with + ground, I got to thinking.  Yes, it hurts.  LOL  Seriously though, WHY did they have almost everything, back in the day, with a + ground?  Just curious.  Thanks

As I recall, Ford was negative ground and GM was positive ground. Either polarity functions so long as the loads are ignition and lamps, though ignition works better with the correct polarity and the ammeter indicates the proper charge/discharge with proper polarity. It still indicates with reversed polarity.

Thing is the generator has to be polarized by flashing when changing the battery polarity or the first time the engine runs it IS going to fry the contacts in the cutout section of the voltage regulator.

Best I can tell the polarity arguments were based on corrosion of the ground connection, but the two connections to ground, that at the starter and that from the battery will corrode in opposite directions so that argument is not great. There were great arguments between owners of underground water pipes and DC trolley operators because the direction of current would either eat holes in the pipe or add metal preserving the pipe. Again that depended on whether the pipe was close to the power substation feeding the trolley wire or distant and whether the water pipe crossed or ran parallel to the rails. If the pipe ran alongside the trolley for a long distance, one polarity would corroded the pipe near the power station, the opposite polarity would corrode the pipe at a distance and preserve the pipe near the power station. I think the auto makers based their argument on the trolley and the pipe corrosion.

The Society of Automotive Engineers, (SAE for short) for more than half a century accepted either polarity. Long about 1957 (and I posted a few times to the form a year or two ago on precise dates and standard numbers) the standard was issued saying that negative ground was preferred. And about 1960 the standard was revised saying SHALL be negative ground.

In the days before solid state, polarity wasn't a problem though radios had to have switchable polarity. A radio with the wrong polarity applied just didn't play, it wasn't destroyed. When solid state came along reverse polarity blew every transistor in the radio instantly. So polarity became more critical.

Gerald J.

Gerald, ya left out the points argument. In the early days they lasted longer with positive ground due to the arc direction and material problems. Later on I don't think it mattered much. Wish I could find the reference.

I had my d17 battery hooked up backwards for a coupler hours of runtime till I read my manual and it didn't seem to harm anything just the amp meter was reading funny... ? ? Now its hooked up right and all is well.. I think .

GM was Neg (-) ground on both 6 and 12 V systems . Ford used the Pos (+) ground up to the time they switched to 12 V. My 66 White truck uses (+) ground also with a Leis Nevill alternator.

Edited by Coke-in-MN - 24 Feb 2012 at 10:11am

I was taught both in school, electron theory and conventional theory but I liked the way he said that electrons go from negative to positive so I believed him.  LOL

Teacher Coke, you talk about copper ions being given off copper wire... Then in theory if you have an electrified electric fence thats charged at 15KV and  you crawl under it in the pouring rain and got both knees and hands  down in the wet grass while soaked to the bone, and electric fence wire is galvanized, Do the galvanized ions go trough your body or do they go around your body or is it just 15KV of human ions leave your body when you happen to get to close and the electricity jumps from wire to wet back?  I couldn't tell if any ions moved in the millie second of snap, All I know is it'll flatten you face first in the mud... 

I'm positively cornfused. I guess I look negitively at certain things?????

I just found a article and read it and posted it , so if it's to deep or wrong then guess I goofed but i thought the theory and ideas from the article were something to think on.