posted
which is the better way to ground an electrical system positive or negative ? someone was saying something to me about a positive ground being better. i know some imports have a positive ground as well as some dodge vehicles. does anyone have any technical insight to inform me with ?
posted
There has not been an american made car with a positive ground since the 40's (or 30's).
Posts: 31 | From: Chicago, IL | Registered: Apr 2003
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posted
Negative ground is the standard and is what all automotive electrical devices are made for. Only some old cars have positive ground and since negative ground is what all cars now use there is probably a reason why this has been the standard for years. In terms of electricity there should be no difference between the two grounding methods. I am not sure why negative grounding is always used but I think it may be because of the chemistry of metals, and the very slight advantage that negative ground has over positive ground for corrosion protection.
Posts: 327 | From: Pleasanton & Sacramento Ca | Registered: Dec 2001
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posted
I know of no advantage to positive grounding. Even the terms positive and negative come from common use. It's just better if we all understand that the ground is the negative terminal. It just avoids a lot of shorts.
The answer to your question is...Neither, they're both the same.
Posts: 768 | From: Ottawa, On, Canada | Registered: May 2000
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Thank Henry Ford for "negative grounding". If you think of it as electrons flowing from negative to more negative, then the terms and colors go out the window.
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wait a second don't electrons (-) flow from - to + therefore the ground is actually the first place where the electrons go before whatever is attached to the rest of it. or are they just trying to confuse me?
-------------------- SQ Here I Come... HC 15 + MMats D300hc = Sounds DAmn Good And IS ve"RE" Loud i love ported boxes and really big unheard of subs http://members.sounddomain.com/oldsjbl Posts: 283 | From: Salinas CA | Registered: Oct 2002
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posted
Depends on what you believe. Many think it is the way you just described(including myself), but others think the opposite. Might be an interesting topic to research and form an opinion.
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As was stated before electrons do flow from negative to positive. But what gets people confused is that current flows from positive to negative, or by its definition it is the direction in which positive charge carriers flow. A long time ago they thought that electricity was the flow of positive charge carriers but they turned out to be wrong and thus today the definition of current flow seems to be backwards from what would be logical.
Posts: 327 | From: Pleasanton & Sacramento Ca | Registered: Dec 2001
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posted
I belive it to be negitive to positive for electron flow
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posted
i learned it from neg to pos also. electrons are - charged and is what does the "flowing". they go from an area of higher concentration to lesser. wether it be a lesser - area, or to an even lesser area that is +.
Posts: 542 | From: nor cal | Registered: Aug 2004
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DDSTANG hit it right on the head...electrons, which represent a NEGATIVE charge, flow from - to +. "Current," usually meant as the flow of POSITIVE charge, is therefore in the opposite direction of electron flow. Kid of confusing, but thats the way it is.
In electrical engineering, there's a charge carrier called the "hole" thats often used to represent a positive charge. Physically, a "hole" is simply the absence of an electron, much in the way that "dark" is really the absence of light.
Ash
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a positive ground on a car theoretically could work, however there are a few problems to say the least as shadow star was giving clues to...
I just wanna see what happens if someone were to have a positive ground to the chassis/frame/engine block crash into a metal light pole! Or even better try to jack up the axle to change a tire....lol
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quote:Originally posted by jnealg: hmmm electron flow or hole flow.... an ages old argument.
What's the arguement? If you look at what I previously posted, that is exactly like all texts on the subject would describe it. Back in the 1800's and early 1900's there was arguement, but there hasn't been any for a long time.
quote:Originally posted by Bumpin' Yota: I just wanna see what happens if someone were to have a positive ground to the chassis/frame/engine block crash into a metal light pole! Or even better try to jack up the axle to change a tire....lol
Why would you want to see this? It would be exactly the same as any other car. If you don't know why this would be, you should learn more about electricity. The reason why is a very basic electrical principal.
Posts: 327 | From: Pleasanton & Sacramento Ca | Registered: Dec 2001
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quote:Originally posted by jnealg: hmmm electron flow or hole flow.... an ages old argument.
What's the arguement? If you look at what I previously posted, that is exactly like all texts on the subject would describe it. Back in the 1800's and early 1900's there was arguement, but there hasn't been any for a long time.
quote:Originally posted by Bumpin' Yota: I just wanna see what happens if someone were to have a positive ground to the chassis/frame/engine block crash into a metal light pole! Or even better try to jack up the axle to change a tire....lol
Why would you want to see this? It would be exactly the same as any other car. If you don't know why this would be, you should learn more about electricity. The reason why is a very basic electrical principal.
Hmmm there would be no commonly shared ground however I don't believe that makes a difference. You energize the car's body with 12v, then ground it out to the earth. Guess what happens - battery discharges as there will be current flow to the earth.
secondarily loose the attitude
quote:Originally posted by ShadowStar: Well.. A car's negative terminal more closely represents earth ground, doesn't it?
I mean.. with a positive ground, aren't you raising your cars common conductive surface to a larger potential above earth ground??
ShadowStar
ddstang you might want to read this, as this is what im refrencing.
So what is this 'basic principle of electricity' that I supposedly need to learn?
quote:Originally posted by Bumpin' Yota: Hmmm there would be no commonly shared ground however I don't believe that makes a difference. You energize the car's body with 12v, then ground it out to the earth. Guess what happens - battery discharges as there will be current flow to the earth.
secondarily loose the attitude
For the battery (or any other power supply) to supply a current there has to be a complete circuit; there is no exception to this rule. Since a cars electrical system is completely electrically isolated from the earth, there would be no way to create a short circuit between it and the Earth.
What is called ground in a car is kind of misleading since it has no electrical connection to the Earth unlike household power which does always have a reference connected to the Earth's ground. The ground in a car is just the negative (or positive in the rare case of positive grounded systems) electrical return and is the reference potential for the car. When measuring a voltage in a car you measure the potential difference between the ground (reference voltage) and whatever you are measuring the voltage of. If you tried to measure the voltage between either of a car's battery terminals (or any battery for that matter) and the Earth's ground you could not measure any potential difference because there is no complete circuit between the battery and ground.
One somewhat common thing that you see sometimes in electrical systems is to have two batteries (or power supplies) with the negative of one and the positive of the other connected to ground; the ground just serves as a reference potential. If you measure the voltage difference between ground and the first batteries other terminal you will measure a positive voltage, just like normal, but if you measure the voltage between the second battery and ground you will have a negative voltage. This is fairly common for DC power supplies (such as inside you computer) where it makes both positive and negative voltages.
Posts: 327 | From: Pleasanton & Sacramento Ca | Registered: Dec 2001
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quote:Originally posted by ShadowStar: Well.. A car's negative terminal more closely represents earth ground, doesn't it?
I mean.. with a positive ground, aren't you raising your cars common conductive surface to a larger potential above earth ground??
ShadowStar
ddstang you might want to read this, as this is what im refrencing.
So what is this 'basic principle of electricity' that I supposedly need to learn?
What he said is wrong too. Since the battery of a car is completely isolated from Earth there is no potential difference between either terminal and the Earth.
The basic principle that you need to know and completely understand is that you need a complete circuit for current flow. This is about the most basic electrical principal that there is. Go and get a battery by itself and a voltmeter and try to measure a voltage difference between either of its terminals and an Earth ground. I guarantee that you will never measure a potential difference.
If the chassis of a car were above Earth's ground potential and it did make contact with the ground it would make a short circuit. But what would make the complete circuit? Current could flow from the car to Earth but how would the circuit be completed from the Earth back to the car?
quote:Originally posted by ShadowStar: Well.. A car's negative terminal more closely represents earth ground, doesn't it?
I mean.. with a positive ground, aren't you raising your cars common conductive surface to a larger potential above earth ground??
ShadowStar
The basic principle that you need to know and completely understand is that you need a complete circuit for current flow. This is about the most basic electrical principal that there is. Go and get a battery by itself and a voltmeter and try to measure a voltage difference between either of its terminals and an Earth ground. I guarantee that you will never measure a potential difference.
If the chassis of a car were above Earth's ground potential and it did make contact with the ground it would make a short circuit. But what would make the complete circuit? Current could flow from the car to Earth but how would the circuit be completed from the Earth back to the car? [/QUOTE]
I was rolling with the analogy that the car's common conductive surface represents earth ground, IE, the battery +12 is +12 above the ground when the negative is grounded. If you wire the +12 to the ground, then you are just raising the common conductive surface +12v over what it would be if it was to the negative, but you'd still need a return to the negative terminal anyway.. (sorry I wasn't very clear here) but obviously you need a circuit for current flow
ShadowStar
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