Classic cars forum & vehicle restoration.

[oldtimer]

I have been challenging this claim for years,relating to vehicles.While I readily accept the benefits, in the marine environment,I refute claims that this,automatically,makes the case for land base vehicles.This assertion has,again,reared its head in a recent conversation in the Halls of Accademe,namely The Cook and Barker,my local.
I am curious which of the many erudite chaps on the forum will agree or oppose my contention in my ongoing search for fact or fiction.As Jim Walker says "The fact that somebody claims to have known someone who knew someone whose aunt's second cousin would verify something or other won't do!"
oldtimer (John Nicoll)

[Keef]

[oldtimer]

Hello Keef
The assertion is that this conversion from positive greatly increased resistance to corrosion in vehicles
oldtimer

[47p2]

There are still numerous cars around that are positive earth John, proof it must work
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ROVER
One of Britain's Fine Cars

[oldtimer]

Hello John
Do I take it you are with me that,unlike the marine evironment,it does nothing to benefit land based vehicles?

[47p2]

From what I've read over the years there was no benefit to having positive earth vehicles. The manufacturers didn't seem to keep making them long which must mean that they also found no significant benefit.
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ROVER
One of Britain's Fine Cars

[Peter_L]

Changing from +Pos Earth to -Neg Earth very likely has a great deal to do with the power of GM (General Motors America) and less to do with the "rust issue"

Nasa's Apollo space program used the first silicon based semiconductors and systems were constructed with -Neg earth. It is likely that GM recognised that the new age of Silicon based semiconductors could be utilised in car production.

GM proposed a standardised - Neg earth system for the auto industry, which was, at first, opposed by Ford, but their objections were more political than practical and they too complied.
GM also owned Delco, so they were already a big wheel in the auto electric industry.

Their defense research organisation manufactured the wheels for the Lunar Lander, so all in all, it was very much a case of what GM wanted GM got.

Once the changes came into place, then so did the stories of polarity and corrosion. However the corrosion issue may have had more to do with a change in materials and manufacturing rather than any electrolytic advantage.

[peter scott]

Hi John,

I'm not sure I understand or agree with all of this but apparently it was writ by Lucas: http://www.rrec-northeast.co.uk/positive_negative.pdf

Peter
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https://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

[Keef]

[oldtimer]

My ancient,chainsmoking Science master explained it thus;salt is sodium and chlorine.Sodium + charge;chlorine - They bond (opposites attract)
Boatbuilders take advantage of this.The negative terminal of the boat's batteryis fitted to themetal hull (marine equivalent of negative earth)The positive is attached to a steel terminal ,an anode,which protrudes through the hull but is isolated from it. The result,in a marine environment,is the boat is afloating battery.Chlorine,being negative is repelled by the hull and attracted to the anode which was designed to be sacrificial and to be replaced from time to time,thus minimising the corrosion damage to the hull.This box of tricks does not transfer,however,to landbased set ups .These are not constantly and continuously immersed in brine,a prerequisite for the system to function and so trying to translate the system to be used on terra firma where the conditions are quite different,and quoting the maritime experience as proof of potency is just to confuse matters further.

[Riley Blue]

[47p2]

[Roger-hatchy]

Must be reference to NASA, looking for ET.
They kept that a secret, space travel in the 30's?
Must have been, thats when NASA decided everybody should be Negative.

[Jim.Walker]

Most continental cars (post war anyway) seemed to have -ve earth before transistors etc. were even dreamed of. The consideration of solid state electronics can therefore be discounted.
There is no doubt in my mind that corrosion build up around the positive terminal of a battery was a continuing problem with +ve earth systems. Cleaning and coating with Vaseline being a regular service item.
That corrosion never seemed to happen with -ve earth, but it was often noticeable that the various electrical connections around the vehicle showed signs of some corrosion build up.
Today I believe the the production of NPN (negative earth) transistors is much cheaper than PNP, which makes the use of -ve earth much more attractive. The only vehicle I have ever come across with a +ve earth alternator and battery is the Daimler DR450 (Majestic Major) series. Lord knows why they differed.
I doubt very much that GM had a crystal ball capable of seeing far enough into the future to predict solid state electronics.
Jim.
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Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then!

[Peter_L]

My posting above, related to the standardisation of polarity, which appears to have been finally agreed on in 1970.

The polarity issues could only go one of two ways. Ford wanted to retain their +ve earth, GM wanted -ve earth.

Anything that may have happened with polarity before then was not the part of the question that I was attempting to answer.

That's it... done.....