Inherent Advantage to Negative Ground?

David in San Antonio

David in San Antonio

Well-known member
Is there any inherent advantage to a negative ground system vs. positive ground? Not 6 volt vs. 12, just the polarity of the ground.
All the car companies switched over, even the English ones (with new stickers warning of "Negative Earth")! Was this for a technical reason?

I propose to be incrementally less ignorant today than I was yesterday.
 
"I propose to be incrementally less ignorant today than I was yesterday."

Some of us go in just the opposite direction, Self included. :)
Marshall
 
Probably because traditional vehicle
construction utilized ferrous metals.
So that allowed a common return
path for DC voltage in the event
of a short circuit if proper bonding
was established.

Jim
 
One incidence where ground polarity made a big difference:

Solar systems have negative ground. This is traditional and not due to any performance advantage. When I worked at SunPower making solar panels (photovoltaic panels, PV), we shipped our initial production to systems with negative grounds. In a few months the panels were putting out about half their rated power. Why?

It turns out that glass is a semiconductor. It can conduct electricity but only very small currents. Over time the glass was becoming negative charged because of the negative ground on the frames. This caused the panels to behave like writable semiconductors where the semiconductors had a static charge. The semiconductors could be erased with a strong UV light. The semiconductors are called EPROMS.

The solar panels recovered their full output power by putting a positive charge on the glass by a film of water which was connected to a positive voltage. I discovered that they could also be recovered using a strong UV light which is how we discovered the reason for the power loss. We had to specify that a positive ground was used on our solar systems. This solved the problem. I was involved in the search for equipment (inverters) that could be used with positive ground solar systems.

The work resulted in a patent and I was named on the patent. The negative ground problem was unique to the SunPower panels due to their high efficiency design.
 
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What a very unique solution to a very odd problem congratulations on being part of a patent that's got to be really special!!!
 
I had a third grade teacher that made it her mission to drive the leftiness right out of the kids.She was pretty brutal about it.But,one of her success stories from about 10 years before me had quite an interesting job on a carrier in the Gulf of Tonkin.He stood behind a glass wall,and as orders for the pilots would come to him in real time,he would write all that info on the glass,backwards,so the pilots could read it and write it down.He could do it with either hand.
 
Leonardo da Vinci would write all his engineering and medical notes backwards so that people could not read them without a mirror.
 
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One gal at a place I worked could write backwards, one needed a mirror to read it. She told me that her grandmother had taught her how to do it when she was quite young.
 
Bob Bidonde said:
With a negative ground you can use modern electronics such as a GPS, cell phone charger, etc.
Click to expand...


You can do the same with a positive ground car, just switch the wires... I was understanding the op's question more as regarding any physical reasons for a negative ground...
 
In those earlier times, electrical engineers were instructed that it was an advantage in the direction of electron flow to have positive ground but further scientific research found the opposite was true. It took a while for that knowledge to catch up with the current technology of the times. The true amount of difference is nearly negligible but folks find out eventually that increased resistance from circuit deterioration make the big difference on how well a 6-volt positive ground system works. The advent of the change over to the higher 12-volt systems made resistance less of an issue no matter which way it was grounded. The British kept positive ground a bit longer than the US did but all eventually changed over.
 
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