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Old 07-12-2018, 11:15 PM   #1
hb32
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Default 6 volt positive ground

I am sure it has been covered but can some one school me on this ? Will be 6 volt in my 32 pickup with a 59A flathead and a pre 39 generator so do I need to have positive ground or can it be negative ground ? Also, have an original amp gauge and does it require positive ground? Can not wrap my head around the concept 🤔
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Old 07-12-2018, 11:21 PM   #2
J Franklin
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Default Re: 6 volt positive ground

Make it + ground and then your wiring diagram will be correct. Why change things?
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Old 07-12-2018, 11:23 PM   #3
Charlie Stephens
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Default Re: 6 volt positive ground

Positive and negative ground will both work. The real question is why change it and confuse those that work on the car? If you go to negative ground the you will need to reverse the wires on the back of the ammeter as it only measures the flow of electrons. You will also need to reverse the wires on the coil. The starter motor will spin the same way with either positive or negative ground. You need to polarize the generator for the negative ground.

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Old 07-13-2018, 07:25 AM   #4
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Default Re: 6 volt positive ground

I would leave it as it is. Remember you don't want to be that "jerk" spoken about by the next owner who "did that".
I know there are current owners that have called me at least a jerk when they inherited some of my teenage electrical bird nests.
Let you without "ingenious short cuts" in your past cast the first stone, Chap.
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Old 07-13-2018, 07:43 AM   #5
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Default Re: 6 volt positive ground

The only REAL difference between positive and negative ground is how the battery is connected.

If you're trying to think your way through imagined differences, your head is going to explode.
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Old 07-13-2018, 07:48 AM   #6
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Default Re: 6 volt positive ground

Leave it positive ground. Remember, these vehicles were driven for many years and thousands of miles as Henry intended. Still works 4 me. m
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Old 07-13-2018, 07:58 AM   #7
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Default Re: 6 volt positive ground

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Originally Posted by Mike51Merc View Post
The only REAL difference between positive and negative ground is how the battery is connected.

“If you're trying to think your way through imagined differences, your head is going to explode”.
I think this is excellent advice. I’ve done a lot of wiring on on neg. ground equipment and I always “ over think” the pos. ground issues.... Mark
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Old 07-13-2018, 08:17 AM   #8
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Default Re: 6 volt positive ground

Agree with Chap, keep it pos. ground as it was originally and it will be easier to remember down the line just what you did. I changed my '39 to negative ground when I replaced the generator with and alternator....the alternator was wired to be negative ground....and I always had to look at the battery to remember what I had done when I replaced things like the electric fuel pump, etc. It's easier for me to remember the "red" wire goes to ground!!!
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Old 07-13-2018, 10:04 AM   #9
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Default Re: 6 volt positive ground

Just a side note. When people change to 12 volts the only reason they change to negative ground is to be compatible with newer electronics that are 12 volts negative ground. Other than the compatibility issue there is nothing better about negative ground. Leave your car positive ground, if it isn't broke, don't fix it until it is.

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Last edited by Charlie Stephens; 07-13-2018 at 10:10 AM.
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Old 07-13-2018, 10:14 AM   #10
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Default Re: 6 volt positive ground

Lots of good advice but still can't figure out why there was a positive ground. My electrical background doesn't comprehend putting a cable from the positive terminal to the frame of a vehicle, am I missing something here?
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Old 07-13-2018, 10:37 AM   #11
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Default Re: 6 volt positive ground

At one time it was considered an advantage to use positive as the groung. With the addition of more modern electronics the advantage switched to negative ground and the manufactures slowly switched over. Solid state devices, diodes, transistors, etc are concerned with polarity, but most of our flathead devices do not and the ones that do (coil, generator, ammeter) are easily adapted. Positive and negative are just names, very few devices care. If you want to add to the confussion, AC is changing + & - 60 times a second!

Last edited by JSeery; 07-13-2018 at 12:56 PM.
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Old 07-13-2018, 10:44 AM   #12
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Default Re: 6 volt positive ground

Both Ford and Chrysler used positive ground for decades. Dont try to overthink what is proven to work, work well, and be reliable. Screw the red wire down and go have a drink.
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Old 07-13-2018, 10:53 AM   #13
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Default Re: 6 volt positive ground

I have heard that positive ground is less susceptible to corrosion problems. With only 6 volts to "push" through the system, I suspect lessening corrosion was more important than it is with 12 volts.
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Old 07-13-2018, 10:54 AM   #14
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Default Re: 6 volt positive ground

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Originally Posted by hb32 View Post
Lots of good advice but still can't figure out why there was a positive ground. My electrical background doesn't comprehend putting a cable from the positive terminal to the frame of a vehicle, am I missing something here?
Doesn't direct current flow from negative to positive? So why not?
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Old 07-13-2018, 12:54 PM   #15
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Default Re: 6 volt positive ground

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Doesn't direct current flow from negative to positive? So why not?
All depends on how you look at it. Electrons have a negative charge, and move toward a positive charge. However you can also look at it as positive holes (missing electrons) moving from positive to negative. It is really not important unless you are into theoretical stuff. There is current moving through a wire and it produces an electric/magnetic field around it. For most applications in older cars it doesn't make any difference which direction the current is flowing as long as it is consistent to the application.
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Old 07-14-2018, 01:07 AM   #16
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Default Re: 6 volt positive ground

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I have heard that positive ground is less susceptible to corrosion problems. With only 6 volts to "push" through the system, I suspect lessening corrosion was more important than it is with 12 volts.

That is true, well maybe. But I think it is so minuscule to other factors like moisture, normal wear, and road conditions.


6v I'd just stay pos ground. Keep it simple. 12v well... go neg ground.


But maybe these work? I don't know... https://www.youtube.com/watch?v=I2B7ozAEe2w

Last edited by Tinker; 07-14-2018 at 01:22 AM.
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Old 07-14-2018, 01:23 AM   #17
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Default Re: 6 volt positive ground

Just to add to your confusion, you can buy a step-up transformer which converts to 12v neg ground to run modern devices. But you have to make sure they are isolated from the car.
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Old 07-14-2018, 08:17 AM   #18
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Default Re: 6 volt positive ground

The question is can it be changed to neg ground? The short answer is yes. Others pointed out how to do it but the original post did not say why he wanted to change it around. If he had we might have been able to give him more pointers. I have 6v pos grnd in my 49 but float a power point to run my GPS. Works fine for me.
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Old 07-14-2018, 09:00 AM   #19
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Default Re: 6 volt positive ground

6-volt systems always needed all the help they could get for reliable service. It was known after the Model T era that the flow of electrons worked better for positive ground. Once the 12-volt era change came in, it was determined that the higher voltage would be fine using negative ground. A lot of electronics were already based this way for non automotive use so it was natural to go this route. In the UK, they still used positive earth on 12-volt systems for a while since they went to 12-volt first but it was eventually changed over for essentially the same reasons.
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Old 07-14-2018, 11:11 AM   #20
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Default Re: 6 volt positive ground

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Originally Posted by Jembow View Post
Just to add to your confusion, you can buy a step-up transformer which converts to 12v neg ground to run modern devices. But you have to make sure they are isolated from the car.

Not with this one. http://www.antiqueautomobileradio.com/


POSITIVE GROUND POWER INVERTERS
Operate modern 12 volt negative ground accessories from positive ground 6, 8, or 12 volt electrical systems!
Our Power Inverters are very small (1"x1"x1"), lightweight (only about 9 oz), quiet, and extremely efficient.
They use a common ground, so isolation is not necessary.
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