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Why positive ground?
- Thread starter Lonnie
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Bret
Yoda
Offline
[ QUOTE ]
Now Bret, I think if you saw a bunch of pot holes in the road commuting to or from work you would try to avoid them. Those little electrons are just as smart and they would try to avoid the pot holes, Rust Spots, too, preferring to travel easier in good metal.---Keoke /ubbthreads/images/graemlins/yesnod.gif
[/ QUOTE ]
Exactly, the point. Just as a driver is going to have to work harder to avoid the pot holes on his way to & from work. Its going to take a little more effort for all those electrons pass through the corroded body of the car.
/ubbthreads/images/graemlins/cheers.gif
Now Bret, I think if you saw a bunch of pot holes in the road commuting to or from work you would try to avoid them. Those little electrons are just as smart and they would try to avoid the pot holes, Rust Spots, too, preferring to travel easier in good metal.---Keoke /ubbthreads/images/graemlins/yesnod.gif
[/ QUOTE ]
Exactly, the point. Just as a driver is going to have to work harder to avoid the pot holes on his way to & from work. Its going to take a little more effort for all those electrons pass through the corroded body of the car.
/ubbthreads/images/graemlins/cheers.gif
Offline
[ QUOTE ]
Also,the spark jumps the opposite direction on the plugs. Take a look at the wear patterns on plugs pulled from each type setup. on a standard neg. ground car the center electrode wears. on a pos. ground car the electrode tab tends to wear more. It was reported to have increased plug life and provide a slight(and I mean very slight) performance advantage.
[/ QUOTE ]
Actually, the polarity of the spark can be changed by simply reversing the two low voltage connections to the coil. If you change from positive to negative ground, just reverse the coil connections. Here is a quote on the subject:
-------------------------------
"CHAMPION
Automotive Technical Service Manual
The subject of polarity often causes confusion and deserves a more
detailed discussion. Over the years car manufacturers have connected
either the positive or negative terminal of the battery to the chassis
but in recent years have adopted a negative earth as standard.
Most electrical components in the car have one of their leads connected
to the chassis, which acts as a common return path to the battery and
completes the electrical circuit of which the component is a part.
The ignition coil however is connected to the chassis only through the
closed contact breaker.
If the leads to SW and CB (or to terminals marked respective '+" and
"-") are reversed, the current flow through the coil primary is reversed
and this in turn reverses the polarity of the coil secondary voltage.
Coils are wound so that the output to the rotor arm is negative with
respect to the chassis but this depends on the correct primary
connections being made.
Spark plugs are sensitive to polarity and they will not function as
efficiently it the secondary coil voltage is of the wrong polarity.
The reason for this sensitivity is as follows. The centre electrode has
a higher temperature, normally, than the ground electrode so that more
electrons will be released from the hotter metal surface of the centre
electrode than from the ground electrode.
If the centre electrode polarity is more negative than the ground
electrode (which is connected to chassis) then the earth electrode will
attract electrons from the centre electrode; but if the coil secondary
voltage polarity is reversed, the voltage needed to cause electrons to
pass from the earth to the centre electrode (i.e. to make the gap
conductive) is increased.
Reversed coil polarity can be shown on an oscilloscope but a less
sophisticated test is to disconnect a plug lead with the engine running
and form an arc between the plug terminal and the end of the cable.
If the point of a soft lead pencil is placed in the path of the arc then
a shower at sparks will be created, either on the plug side (if polarity
is correct) or on the cable side (if the polarity is incorrect). The
condition of the plug will also indicate reversed coil polarity if this
situation has prevailed for some time. The use of the oscilloscope is a
more sophisticated means of determining the states of the engine,
ignition and fuel systems than the condition of the spark plug.
All the best
John Harper"
--------------------------------
D
Also,the spark jumps the opposite direction on the plugs. Take a look at the wear patterns on plugs pulled from each type setup. on a standard neg. ground car the center electrode wears. on a pos. ground car the electrode tab tends to wear more. It was reported to have increased plug life and provide a slight(and I mean very slight) performance advantage.
[/ QUOTE ]
Actually, the polarity of the spark can be changed by simply reversing the two low voltage connections to the coil. If you change from positive to negative ground, just reverse the coil connections. Here is a quote on the subject:
-------------------------------
"CHAMPION
Automotive Technical Service Manual
The subject of polarity often causes confusion and deserves a more
detailed discussion. Over the years car manufacturers have connected
either the positive or negative terminal of the battery to the chassis
but in recent years have adopted a negative earth as standard.
Most electrical components in the car have one of their leads connected
to the chassis, which acts as a common return path to the battery and
completes the electrical circuit of which the component is a part.
The ignition coil however is connected to the chassis only through the
closed contact breaker.
If the leads to SW and CB (or to terminals marked respective '+" and
"-") are reversed, the current flow through the coil primary is reversed
and this in turn reverses the polarity of the coil secondary voltage.
Coils are wound so that the output to the rotor arm is negative with
respect to the chassis but this depends on the correct primary
connections being made.
Spark plugs are sensitive to polarity and they will not function as
efficiently it the secondary coil voltage is of the wrong polarity.
The reason for this sensitivity is as follows. The centre electrode has
a higher temperature, normally, than the ground electrode so that more
electrons will be released from the hotter metal surface of the centre
electrode than from the ground electrode.
If the centre electrode polarity is more negative than the ground
electrode (which is connected to chassis) then the earth electrode will
attract electrons from the centre electrode; but if the coil secondary
voltage polarity is reversed, the voltage needed to cause electrons to
pass from the earth to the centre electrode (i.e. to make the gap
conductive) is increased.
Reversed coil polarity can be shown on an oscilloscope but a less
sophisticated test is to disconnect a plug lead with the engine running
and form an arc between the plug terminal and the end of the cable.
If the point of a soft lead pencil is placed in the path of the arc then
a shower at sparks will be created, either on the plug side (if polarity
is correct) or on the cable side (if the polarity is incorrect). The
condition of the plug will also indicate reversed coil polarity if this
situation has prevailed for some time. The use of the oscilloscope is a
more sophisticated means of determining the states of the engine,
ignition and fuel systems than the condition of the spark plug.
All the best
John Harper"
--------------------------------
D
Nunyas
Yoda
Offline
ok, I'll toss in my 2 pennies for this conversation. When I was in high school (many many moons ago), I remember my sister doing a science fair project that involved corrosion of metal plates. The experiment entailed her placing the small metal plates into mason jars filled with a saltwater solution. Container 1 was the raw unprotected bar in the solution. Container 2 was a wax coated bar. Container 3 was a painted bar. Container 4 raw bar protected via anode. Container 5 cathode. I can't remember her exact results, but it's easy enough for anyone to setup and run themselves and the visible results would be apparent wthin a day or two.
From a college Physics/Chemistry stand point, oxygen inheirantly carries a minute negative charge (electrodes placed in water can sepparate the covalent bond between oxygen and hydrogen; with oxygen being captured near the positive electrode and hydrogen being collected near the negative electrode). So, the theory would be; if your car is anode grounded, then the body of the car would have a minute positive charge, and therefore the body of the car would be more attractive to the oxygen in the air. Which in turn, would promote the corrosion of any exposed metal on the car.
Cathode grounded systems give the body a minute negative charge, which would have a tendency to repel oxygen in the air, and therefore retard the corrosion of exposed metals.
From a college Physics/Chemistry stand point, oxygen inheirantly carries a minute negative charge (electrodes placed in water can sepparate the covalent bond between oxygen and hydrogen; with oxygen being captured near the positive electrode and hydrogen being collected near the negative electrode). So, the theory would be; if your car is anode grounded, then the body of the car would have a minute positive charge, and therefore the body of the car would be more attractive to the oxygen in the air. Which in turn, would promote the corrosion of any exposed metal on the car.
Cathode grounded systems give the body a minute negative charge, which would have a tendency to repel oxygen in the air, and therefore retard the corrosion of exposed metals.
Roger
Luke Skywalker
Offline
[ QUOTE ]
I thought that my MG was postive ground because the English have to everything different. They do drive on the wrong side of the road.
[/ QUOTE ]
Steady on old chap. Matter of fact, most of the world kept left until Napoleon - frees up the sword-arm dont y'know, so you can defend against scurrilous villains.
I thought that my MG was postive ground because the English have to everything different. They do drive on the wrong side of the road.
[/ QUOTE ]
Steady on old chap. Matter of fact, most of the world kept left until Napoleon - frees up the sword-arm dont y'know, so you can defend against scurrilous villains.
1963MGBScott
Freshman Member
Offline
Cool lots of great ideas and thoughts but sorry to burst your bubble guys’ electricity does not flow, especially from negative to positive. If you place one atom of conductive material next to another with fewer electrons the atom with the greater number of electrons will join with the atom with fewer virtually spitting an electron into the atom with fewer electrons. If you put new electrons in a conductor, they will join atoms, and each atom will spit out an electron to the next atom. This next atom takes in the electron and spits out another one on the other side. This is what is commonly known as conduction (so the electrons only move a short distance). At the end of the day the energy can be released to perform work measured in WATTS. I am just full of IT!
I look forward to picking each of your brains for my 63 MGB project.
Thanks!
I look forward to picking each of your brains for my 63 MGB project.
Thanks!
danmas
Jedi Trainee
Offline
[ QUOTE ]
so, the theory would be; if your car is anode grounded, then the body of the car would have a minute positive charge,
[/ QUOTE ]
The body would have a positive charge with respect to what? Only to the negative post of the battery. It would be neutral with respect to anything else.
or would it?
so, the theory would be; if your car is anode grounded, then the body of the car would have a minute positive charge,
[/ QUOTE ]
The body would have a positive charge with respect to what? Only to the negative post of the battery. It would be neutral with respect to anything else.
or would it?
SilentUnicorn
Yoda
Offline
Face it fellas ...they still RUST
mark
mark
dklawson
Yoda
Offline
You know... all this discussion supposes that the folks at BMC, Standard Triumph, Rootes and the others actually sat down and had a discussion about rust, anodes, and cathodes.
I seriously doubt anyone at those companies said "Hey, I've got an idea to minimize rust". More likely, company 'A' said, "What ground is company 'B' using?" and copied them. Or... company 'A', 'B' and 'C'" all said to their radio or other electric accessory suppliers... "Hey, what ground are you designing those things for?" When there is a lack of standards, the suppliers dictate the norm.
I seriously doubt anyone at those companies said "Hey, I've got an idea to minimize rust". More likely, company 'A' said, "What ground is company 'B' using?" and copied them. Or... company 'A', 'B' and 'C'" all said to their radio or other electric accessory suppliers... "Hey, what ground are you designing those things for?" When there is a lack of standards, the suppliers dictate the norm.
Nunyas
Yoda
Offline
[ QUOTE ]
The body would have a positive charge with respect to what? Only to the negative post of the battery. It would be neutral with respect to anything else.
or would it?
[/ QUOTE ]
It would be positively charged with respect to anything that's less positively charged (e.g. an O2 molecule carrying that minute negative charge). Get some positvely charged iron and some negatively charged oxygen and you have the potential for a faster rusting chassis... at least that's one theory.
I may have to run out and find some scrap metal and 9V batteries to experiment with... just for kicks... /ubbthreads/images/graemlins/smile.gif
The body would have a positive charge with respect to what? Only to the negative post of the battery. It would be neutral with respect to anything else.
or would it?
[/ QUOTE ]
It would be positively charged with respect to anything that's less positively charged (e.g. an O2 molecule carrying that minute negative charge). Get some positvely charged iron and some negatively charged oxygen and you have the potential for a faster rusting chassis... at least that's one theory.
I may have to run out and find some scrap metal and 9V batteries to experiment with... just for kicks... /ubbthreads/images/graemlins/smile.gif