Landrover alternator problem

[tytower]

I have an old landrover that used to be POSITIVE earth.
I tossed the generator and replaced it with a NEGATIVE earthed alternator quite some years ago.
I would like to convert it back to positive earth but without the generator.
How can I convert a neg earth alternator to make it a positive earth alternator?

 

[mneary]

Half of the diodes are probably seated in the frame. Isolate the diodes, and design a new regulator.

 

[tcmtech]

Find one of the many industrial application alternators that have both positive and negative terminals coming out the back. Then just choose which one you want for the ground side.

Why would you want to convert it back? Is being compatible with other vehicles and typical accessories causing problems?

 

[tytower]

Cars have been designed for negative ground because they rust away quicker that way . The electrons are all over the body of the car all the time looking for a path back to positive . If you doubt that then my Landrover is the proof you seek . It is 60 years old and goes perfectly and rust has suddenly become a problem in the last 5 years since switching polarity . It has lived outside and never been garaged in the 30 years I have owned it in the wetest part of NSW . Lismore ,where I bought it.(In Australia). They have aluminium body panels surely but all the structural framing is steel.

I have not seen such an alternator with both outputs.

Half of the diodes are probably seated in the frame. Isolate the diodes, and design a new regulator.

I don't understand that one . In my alternators all the diodes are in a frame earthed .Half face one way and half the other . So what do you mean . I seek a readily available alternative or an easy conversion not a redesign task.

 

[tcmtech]

System polarity is relative to the source of electron flow only.

Physics doesn't differentiate which is which polarity wise in regards to that actual metal in the vehicle. The vehicles metal can be both polarities simultaneously if two independent voltage sources are used.

A simple example of that would be this. Which polarity is the earth?

The rust problem is more likely due to a change in the conditions you are in environmentally. Or simply to the fact that the vehicle is 60 years old.
I suspect that even with the reversing of the system voltage it will continue to rust as fast or faster than it is now.

 

[tytower]

Well you are wrong . I don't expect I will convince you of that.

The vehicles metal can be both polarities simultaneously if two independent voltage sources are used.

No. if this is the condition you have a circuit

The earth has a constant positive charge at the body of the earth and electrons are created in the atmosphere in many ways.

Your argument though has been advanced many time in many ways but if you want to know the truth put two similar samples of a metal in the outside air and connect them to the same battery but positive to one and negative to the other.. Electrons will flow from the negative to the positive .

 

[kchriste]

The argument would be valid if one side of the battery was connected to earth ground and the other side to the frame. But it is not.

 

[tcmtech]

Sorry but the polarity of the electrical system causing a vehicle to rust theory has been debunked long ago. Any first year chemistry or physics student and some of the better high school students can understand how and why its just not a factor in the actual formation of rust on vehicles.

Given the complex bases and acids in common dirt and organic materials vehicles are exposed too its easily shown how environmental influences however do account for an oxidation or decomposition effect to occur on any metallic material. Its just basic chemistry in action.

Most likely what has happened is that your vehicles protective layers of paint and the more resilient outer shell of metallic oxides that form during the manufacturing processes has deteriorated and the more susceptible inner core of the metal is now exposed.
That tough outer skin has begun to break down after 60 years and the purer inner steel is exposed which corrodes and rusts far faster. Once it starts blistering it rapidly breaks up the surrounding skin and grows.
Thats why they call it cancer on vehicles. Once it starts it either has to be dealt with quickly and often with evasive efforts or it quickly takes over and destroys the very material its apart of.

This is a very common effect I see on antique machinery as well. After so many years the metal just starts to break down regardless of what polarity of electrical system is used. Even Machinery without any electrical systems has the same effects occurring in the same relative time periods. Its just natures way of reclaiming the materials.

If you would like I can put in a word with the local witch doctor and he can shake a magic stick in your general direction while doing a dance. That might prove itself to be just as useful as the reversing of the polarity of the electrical system will! (or it could counter act it too.)

 

[tytower]

I think you must work in the american car industry on their payroll at least to go to such lengths .
Thats bunkum and you know it

 

[Nigel Goodwin]

I think you must work in the american car industry on their payroll at least to go to such lengths .
Thats bunkum and you know it

Sorry, I'm with everyone else - battery polarity makes no difference - and your consiracy theory that it was changed to negative earth to make cars rust is ludicrous. Positive earth cars rusted just the same.

If you want to do it, for your bizzarre reasoning, as suggested you need to completely redesign the regulator and rectifier systems - but physical constraints are likely to be your biggest problem.

 

[magpie]

Cars have been designed for negative ground because they rust away quicker that way .

This is the most ridiculous statement I have ever heard in my life!

 

[shortbus=]

This is the most ridiculous statement I have ever heard in my life!

Of course it is! Everyone knows they use negative ground to keep them from getting better mileage

 

[tcmtech]

No No No! Everybody's wrong.

The whole reason vehicles and everything else rusts faster now is because of the billions of electronic devices that have the common negative side of their DC electrical systems tied to the earth ground line of the AC supply systems.
Because of that the earth is now a giant negative ground source.
Plus all those giant high voltage DC grid systems they are using around the world now have the earth tied to one line as well.

Where ever you get your information from is clearly wrong.
I know mine is right because my witch doctor friend told me all of this while doing a dance and pointing a magic stick at me! So I know its true!

 

[tytower]

The argument would be valid if one side of the battery was connected to earth ground and the other side to the frame. But it is not.

Years ago we used to have earth straps to get rid of static electricity. They worked well . Without them people got car sick often.

Tyres were developed with high carbon content to allow this charge to escape via the tyre and that practice is still in use today.
Consequently your negative terminal is always in contact with the earth and the body and the tyres always carry a negative charge. That charge flows to earth continuously. The positive terminal can be seen accurately as an air gap capacitor. Some capacitor leakage is always present and will be worse with moist or say moist and salty conditions.

Whether you clowns agree or not does not interest me . I know by lengthy practical experience . You know by rote pushing computer keys and practicing at giving the other guy a hard time with posts on reputation and such crap.

Continue as you wish . I answered why because one poster has the bad manners to , rather than simply answer the post , rudely question the reasons why. Why is my business anyway . So mind your own bloody business in future. Oh and Iv' given you some reputation back

 

[Hayato]

Ok. As far as I know, rubber has a high dielectric breakdown.

My car has rubber tyres and I get shocked some times, how can you explain that?

 

[tcmtech]

Pure rubber does but tytower does have a valid point.

They do in fact make the rubber in car tires very slightly conductive (its still in the several mega ohms per inch range) in order to bleed of the static electricity that is generated by the microscopic dust particles in the air that rub against your vehicle as it moves.
However being that resistance is very high it does take a few moments in order for the static charge to bleed down which is more than a long enough time for a person to get a shock from.
If your wearing fairly damp or conductive footwear or none at all and are touching a part of the door that has an conductive connection with the rest of the vehicle you will easily become the lowest resistance path and get shocked as you get out.
Just the action of certain fabrics rubbing on the seats as you get in or out can do it too!

Many fuel transport trucks still do have a flexible metal strap or small chain that hangs down below them and brushes the ground just as an added safety precaution against the unlikely but real possibility of accidental ignition of vapors from static electricity.

But they still rust just like everything else.

 

[Hayato]

I just think that the air moisture has the major role in bleeding the electrostatic.

The slightly conductivity is due the rubber vulcanization (Goodyear, 1839) in order to make it stronger and more durable, not to discharge the electrostatic charge.

When the humidity is too low I get shocked, when it is rainy weather I don't.

 

[tcmtech]

Thats likely possible as well.
I just learned it as having been on purpose for part of my Has-mat training for truck driving for a welding supply company some years ago. It was just one of the answers to a possible odd question that could have came up during the test.

I suspect that only a tire manufacture could tell us the real truth.

 

[Nigel Goodwin]

Ok. As far as I know, rubber has a high dielectric breakdown.

My car has rubber tyres and I get shocked some times, how can you explain that?

It's not the car giving YOU a shock - it's YOU giving the car a shock.

It's your trousers rubbing on the car seat that statically charges you, then when you get out and touch something (usually the car) it discharges.

A guy at work used to have the same problem, and we tried dangling things from the bottom of the van before we realised it wasn't the van

 

[mneary]

I suspect that only a tire manufacture could tell us the real truth.

The tire manufacturer won't tell you the truth. The real reason your car rusts is that today's tires only bleed off positive ions. (The negative ground battery helped promote rust, but now the tires do a better job.) The tire companies are also on the payroll of the auto manufacturers. These same tires keep the fuel charged to the wrong polarity, which is why half of your fuel is wasted.

It will do you no good to change the battery polarity unless you get special negative polarity tires.