positive to ground 6v

[Brent L]

I have just acquired a 1948 dodge B1D. I was told it is positive to ground 6v. the battery positive wire is connected to the starter? How do I determine if it is positive to ground? would it be on the generator?

 

Thanks,

 

Brent

[casper50]

if the positive goes to the starter then the negative goes to the ground.  It is negative ground

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Edited April 18, 2016 by casper50

[busycoupe]

These vehicles were originally wired with the positive battery post grounded to the engine block and the negative post connected to the starter charging circuit. Someone has apparently converted yours to negative ground. If your charging system and gauges are working OK then you should probably leave it the way it is. It is possible to change it back to positive ground, but that may involve re-polarizing the generator and possibly other changes. Get familiar with the way your truck works and get a service manual for it. Then tackle the electrical system if needed.

[Brent L]

Thanks guys, Just don't want to cook anything. It seems when power is on and I honk the horn the gauges go wonky but the engine still turns over but very slowly. still working on getting it running.

Also I put 10w-40 in it and was then told that I shouldn't put oil with detergent in it. Should I just drain it again and use straight 30W.

 

Brent L

[greg g]

What size battery cables are onthe car?  which wire on the coil goes to the distributor?  When the engine is running does the amp gauge show a positive charge? 

 

From the factory the 6V system is wired for positive ground.  most people, not nowing any better,  just assume based on modern vehicles that all vehicles have been negative ground.  Being that most folks think this way they often put the battery in the way they are used to ir negative ground.  The car will still run, the lights will work and the starter will work because they are notsensitive to ground.  But the coil should be wired to reflect the way the battery is installed.  Many thime the car will run fine through all driving conditions, but some may break down at higher RPM's and some will tend to burn out ignitionpoints then run rough because of that.  The is why I mentioned checking how the coil wires are attached.

[Brent L]

Not sure about the coil. Will look into it. What about the 10w-40 versus the 30w

[Reg Evans]

Drain the oil and stick your finger into the drain hole and feel the bottom of the pan.  If there's a thick layer of sludge don't use the detergent oil.

[Brent L]

Thanks will do

[Young Ed]

Drain the oil and stick your finger into the drain hole and feel the bottom of the pan.  If there's a thick layer of sludge don't use the detergent oil.

 

 

Thanks will do

 

Make sure to wear a glove. If you do find a layer of sludge at the bottom it's quite likely to be full of lead from leaded fuel.

[Bingster]

That's  a good point about the lead in the oil.  So where do you dispose of that oil after the first change?

[Young Ed]

That's  a good point about the lead in the oil.  So where do you dispose of that oil after the first change?

Same as any other used oil.

[Brent L]

Eco Station

[Brent L]

Yup. Just inform them. might go in the                                                                                                                                                                         ll

lead paint area

[dpollo]

There is absolutely nothing wrong with 6 volt positive ground systems.  All Fords, Chrysler Products and many other cars except General Motors were wired this way.  There are several reasons why,  including a little known phenomenon called Pelletier's Principal.

In practical terms it makes little difference as long as all components are compatible including the ignition coil.

 

The best advice I can give you is to restore your electrical system to factory specs.  Re polarizing a generator involves a two second procedure with a jumper wire across the cut out relay.

 

Nothing else is very complicated.

 

 If you want to "update" to 12 Volts, negative ground then go for it, but it is not a piecemeal process. It is necessary to reverse the ammeter connections so it will read correctly and  to install a voltage limiter in the gas gauge circuit.

[Dave72dt]

If you think you need non detergent, be sure to specify it.  A straight weight oil does not necessarily mean it is non detergent.  Non- detergent oil will say non detergent.

[HotRodHerman]

Hello to all forum members! My name is Tom, I live in Germany (Bavaria) and I am new here in this forum. The reason for joining this forum is that I have bought a 1950 Dodge Coronet about 2 months ago. Except a repaint it is original, completely rust free and in exceptionally good overall condition for it´s age. I have had several classics, but this is my oldest so far and it forces me to get familiar with some technical Mopar specialities… so here´s my first question: according to the manual and all informations I found so far, these cars have a positive to ground electrical system. But in my car I found the negative battery terminal connected with the ground (engine block and body) and the positive connected to the solenoid…. strange thing is: car starts, runs and everything works just normal, including the original radio (!), which still plays. I have heard, that the radios usually won´t work with changed polarity… is that true? If it is, someone might have intentionally converted the electrical system, but in my opinion it is more likely that someone unknowing had the battery installed the wrong way. Can anyone give me an advice how to proceed? How can I see if any conversion has been made or not? Should I change back to positive to ground or leave it as is?

 

@Greg: you say the coil should be wired to reflect the way the battery is installed – how can I see that (yes I admit, I am NOT an electrical expert…)?

 

I will be going  through the whole car in the near future and will come back with more questions for sure…

[Merle Coggins]

If the Ammeter swings to the Positive side when the engine is running I would suspect that the previous owner has made the change to Neg ground. And to answer for Greg, on your coil the two small wire terminals should be marked + and -. For a Negative ground system the + should be connected to the ignition and the - would be connected to the distributor. For Positive ground it would be the other way around (+ to the distributor)

 

Is it still 6 volt, or has it been upgraded to a 12 volt system? That would better explain the change to Neg ground.

 

Merle

[HotRodHerman]

Thank you Merle. Yes, it is still 6V and it still has all original components. I will check for the Ammeter and the connections ant will see what I can find out... Hopefully the radio has not been hurt so far... 

[Niel Hoback]

If the radio still has a vibrator in it, changing the polarity will not hurt the radio. The vibrator is an electro-mechanical device that changes the input power to AC from DC.

[DonaldSmith]

Vibrator- from DC to AC, so that the transformer can boost the voltage to 200 or so, then rectified back to DC, to work in the tubes.  

The heater circuit for the tubes, and the speaker circuit, remain at 6V DC.  Before supermagnets, the speaker needed a 6-volt electromagnet.  

[HotRodHerman]

So.. I checked the connections yesterday and found all of them to be correct (like original). Which means some dork (may I say that) has wrongly connected the battery. I just turned it 180° and recreated the positive to ground system. Now the amp needle ist moving in the "charging" direction with the engine running... can anyone tell me what the amp should show when idling? The needle will stay right before 20 and will not move up at higher revs...

 

Ah, and yes, the radio is still playing, so we have the proof that it can handle both polarities

[DonaldSmith]

The amp reading at idle will vary with the charge of the battery and the electrical load.

 

With the battery fully charged, and no loads like headlights or radio, the amp needle should be at or near zero. 

 

With a generator, the amp reading may be negative if there are loads like the headlights or an old-style radio.  With an alternator, the reading should be near zero.  If the battery is not fully charged, an alternator can charge it at idle, and the ammeter may show positive.  

[Young Ed]

So.. I checked the connections yesterday and found all of them to be correct (like original). Which means some dork (may I say that) has wrongly connected the battery. I just turned it 180° and recreated the positive to ground system. Now the amp needle ist moving in the "charging" direction with the engine running... can anyone tell me what the amp should show when idling? The needle will stay right before 20 and will not move up at higher revs...

 

Ah, and yes, the radio is still playing, so we have the proof that it can handle both polarities

 

It may be that the person who reversed the battery also reversed the wires on the gauge. Is it reporting the opposite of what it was before?

[Plymouthy Adams]

depending on the meter to gauge any level of charge is not a good method of check except to indicate direction of current flow...get a good ammeter and shunt across the battery and test your output...eliminate the guessing..

[dale]

When I was a young guy I put a Chevy 265 with powerglide in my 46 Plymouth. I changed to 12 volt battery and only changed light bulbs and reversed the ampmeter connections. Never changed anything else except put in a voltage reducer ahead of the radio. Never changed the fuel sender or horn relay. Drove it for several years trouble free. Didnt know much about electrical circuits etc. Everything worked fine.