Negative ground advantage?

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Thanks Danno! We'll be in the Bath, England for 5 months, Jun-Oct and I'll check it out!

Book 'em! ;)
 
I did a bunch or research re neg ground/pos ground and discovered:

In the USA Neg ground became the standard in 1955. Up to that time, Ford was predominantly Pos ground, Chevy was Neg. Other manufacturers were mixed in their usage. The impetus to make the change originated with suppliers of ancillary electric parts. The major points for Neg ground was: 1. The single biggest manufacturer volume wise (Chevy) was using it. 2. Neg ground was less expensive because it used approximately 1/2 the wire -at the time, Neg ground used the chassis as a return (as per today); Pos used a wire. Pos ground was seen as better quality-wise because it used dedicated two-way wiring but Neg ground was seen as less complicated, much cheaper, and "good enough" circuit-wise. So here we are!
 
If one were to swap polarities from positive ground to negative ground, does this require a different polarity smoke?
 
MexicoMike said:
I did a bunch or research re neg ground/pos ground and discovered:

In the USA Neg ground became the standard in 1955. Up to that time, Ford was predominantly Pos ground, Chevy was Neg. Other manufacturers were mixed in their usage. The impetus to make the change originated with suppliers of ancillary electric parts. The major points for Neg ground was: 1. The single biggest manufacturer volume wise (Chevy) was using it. 2. Neg ground was less expensive because it used approximately 1/2 the wire -at the time, Neg ground used the chassis as a return (as per today); Pos used a wire. Pos ground was seen as better quality-wise because it used dedicated two-way wiring but Neg ground was seen as less complicated, much cheaper, and "good enough" circuit-wise. So here we are!
Click to expand...


Eons ago I was taught in U.S. Navy electronics school there are two theories of electron flow. One, electrons flow from positive to negative, conventional theory, the other being electron theory where electrons flow from negative to positive. I recall the instructor at the time, a somewhat short, very rotund Chief Petty Officer, saying the British favored the electron flow theory, whereas on the other side of the pond electrons where considered to flow from positive to negative. Hence, I assumed this was the reason for early British motorcycles and cars having a positive ground electrical system. Your research indicates other factors.
 
It was posited that current flowed from + to -, before it was realised that there was a flow of electrons from cathode (-) to anode (+).

The term “conventional current” is sometimes used, meaning a current from + to -, which might be imaginary, or might be the spaces between the electrons moving the opposite way from the electrons.

Frame or chassis return is as poor a system with either polarity.
 
My wiring was in good shape so I saw no reason to change it. I have wiring for a GPS, USB, alarm and battery charger. The LED headlight bulbs I have tried don’t seem to care either way. LED taillight bulb was sourced for (+) earth application. As long as they are fused properly and not chassis grounded there should be no problems. The only issue I had was the alarm, it needed +V switched power. I had to install a relay to get that to happen.
If I was to start from scratch I would seriously consider (-) earth because it is the standard now and honestly more instinctive for me to work with.

Pete
 
If you are going with a stock bike or a full restoration, stick with positive ground. As soon as you start modifying you may want to seriously consider switching.
 
Deets55 said:
My wiring was in good shape so I saw no reason to change it. I have wiring for a GPS, USB, alarm and battery charger. The LED headlight bulbs I have tried don’t seem to care either way. LED taillight bulb was sourced for (+) earth application. As long as they are fused properly and not chassis grounded there should be no problems. The only issue I had was the alarm, it needed +V switched power. I had to install a relay to get that to happen.
If I was to start from scratch I would seriously consider (-) earth because it is the standard now and honestly more instinctive for me to work with.

Pete
Click to expand...


If the lights work with either polarity they are not LEDs. LEDs will only emit light when forward biased.
 
MexicoMike said:
What specific LEDs did you use for the various lights - headlights, blinkers, tailight/stoplight?
Click to expand...

I cannot answer specifically, as I am on the road, and do not have access to my notes. I will PM you with this info when I return home in 3 weeks. Anyone else wishing this info, PM me.

Slick
 
JimC said:
If the lights work with either polarity they are not LEDs. LEDs will only emit light when forward biased.
Click to expand...


Jim,
The headlight has a solid state box in line with the power plug. What ever that box does allows the bulb to function either way. Interesting fact, I cut the three prong plug off the power wire to hard wire it in. The bulb stopped working, I reinstalled the factory plug and everything worked as normal. That would seem to indicate there is something in that plug assembly also. It’s absolutely a LED bulb. I’m not the only person with this bulb as a got the lead on this forum. It’s been in for almost 5 years so I probably can’t find any paper work on it. I never really tried to overthink it. I installed it and it worked, then I moved on to the next project.
Pete




EDIT:
Specs on a different bulb, but look at where it says polarity sensitive
Negative ground advantage?
 
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All the Headlamp LEDs I have bought are dual polarity out of the box, they have a rectifier array included to cope with any polarity and also voltage bucks which down rate up to 30v down to 5v for the led diodes, so they also work in 6V,12V and 24V systems of both polarity.
 
So what it seems to come down to is this. If you want to use a device that uses the chassis as a ground return, and requires a negative ground system, you can either work out a method of isolating it from the chassis and using a wire return to the battery instead, or you can change the bike to a negative ground system. If you don't have that need, you can stick with the positive ground, or change to negative, just to annoy the purists, as you wish.

Otherwise, no technical reason to choose one or the other. Lots of practical reasons to stick with positive ground, i.e. why fix something that isn't broken. But if you plan to make major changes (on-board computer systems, EFI conversions, extensive sensors and data logging, traction control and ABS, SATCOM, surface-to-air missile control:)), it might be simpler to just convert to negative ground.

Ken
 
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