Will a 6 volt postive ground car still run if you reverse the battery terminals and negative ground it?

[marcapra]

I just saw a video of a mechanic hired to get a 48 Chrysler Town and Country sedan fixed up to sell.  The mechanic is not that familiar with Mopars of this era, so he assumes that it is negative ground.  I thought that it wouldn't run if he grounded the negative post of the battery, but it did run that way.  Does that sound right?  Also the lights worked, but he didn't mention if the gauges read correctly.  In your experience, what would happen if you grounded the negative post of the battery on a postive ground car?  

 

Edited November 17, 2023 by marcapra (see edit history)

[41 Su8]

Probably nothing major. Your gauges May read backwards and you may get metal migration at the points and plugs.

[Bloo]

Not recommended, but it will probably run and charge. Ammeter will read backwards. Spark might be weak. If it's got an M6 transmission, it might not shift (not sure). Sometimes even the radio will work, but I wouldn't count on it. You might damage something. Voltage regulators in those days had various precious metals on the various point contacts, and those would be backwards, so the regulator points might not last long. Gauges could vary. Any electric ones in a Chrysler are probably thermal, and might even read correctly (not sure).

[Steve_Mack_CT]

Working on sorting my first Model A I remember reading a common mistake with "A"s was to reverse coil polarity when replacing the coil.  Car will run but as noted above a weak spark is an issue.  I checked and sure enough, prior owner had the coil backwards.  I did see a noticeable improvement after that correction!

[Old buicks 2]

You need to also repolarize the generator

[DFeeney]

I believe when coils are designed, they are polarity concuss for maximum output.  A engine by itself will run with the battery input reversed but will only achieve about 90% of the maximum coil output.  I am looking forward to reading the post from the "Theory Experts".  I have learned many things from this forum. 

[Farmallregular]

2 hours ago, DFeeney said:

I believe when coils are designed, they are polarity concuss for maximum output.  A engine by itself will run with the battery input reversed but will only achieve about 90% of the maximum coil output.  I am looking forward to reading the post from the "Theory Experts".  I have learned many things from this forum. 

The issue with the ignition coil is that you want the center post on the spark plug to be negative.  It's hotter than the ground electrode, and therefore emits electrons easier. 

 

Starter & bulbs don't care, ammeter will read backwards (can be fixed by simply swapping the terminals on the back), generator will likely need to be re-polarized.  Not sure what'll happen with electric gauges.

 

Keith

[marcapra]

The only electric gauges on a 48 Chrysler are the ammeter and the fuel gauge.  The oil gauge and the temperature gauge are directly connected to the engine.  I wonder how many modern day mechanics have hooked up 6 volt Mopars and Fords with the negative post of the battery to ground without checking the shop manual or Chilton's?

[Rusty_OToole]

Years ago a friend of mine had a Triumph TR3 with a dead battery. He got someone to boost it but they connected the cables backwards. He did not know this, drove about 50 miles and charged up the battery backwards. Apparently this is possible but once the battery polarity is reversed you can't change it back without ruining it. At least that is what he said. Never heard of this happening to anyone else.

[c49er]

I had a guy charge a 6 volt backwards too.

Stupid.

[John n Miller]

I believe that any electrical component will run backwards.  Motors like blower and wipers 

 

[Frank DuVal]

9 minutes ago, John n Miller said:

I believe that any electrical component will run backwards.  Motors like blower and wipers 

Motors that have permanent magnets will run backwards, as the magnetic field is the same as it was, now the armature magnetic field from the current running through it is opposite, so the shaft turns the other way.

 

Motors that have electrically derived fields will run the same way, as now the field and the armature have the same relationship. Hence why starters operate fine on reversed polarity. 🐳 🐈‍⬛🚋

[Highlander160]

You're all missing the elephant in the room. Yes it starts and runs, but backwards! 1 fwd speed and 3 reverse!🤭 🤪😅

[28 Chrysler]

1 hour ago, Highlander160 said:

You're all missing the elephant in the room. Yes it starts and runs, but backwards! 1 fwd speed and 3 reverse!🤭 🤪😅

You forgot , the wipers will not wipe the water off but will add more.

[DFeeney]

Also remember, If the battery polarity is reversed the dome light will bring "Darkness" into the car.

[Highlander160]

That above reminds of the guy who bought Super ign system said to give 30% better gas mileage, a wonder carburetor said to make mileage 50% better, and set of low resistance tires that claimed 25% better fuel mileage. Put it all on and the dadgum gas tank overflowed!

[californiamilleghia]

OK.....thinking about this for positive ground British cars if  battery put in as negative ground.......

 

Will the starter turn the right direction ?

and will the fuel gauge work ?

Wiper motor ?

 

I doubt the radio will work , but will it be damaged ?

 

Thanks for your thoughts

[28 Chrysler]

Who made the wiring? 

The starter won't care, could you tell if the wiper motor turns backward? The fuel gauge will work backwards.

I used this to my advantage friends would give me gas money when I had most of a tank of gas.

A solid state radio could get fried.

[ron hausmann]

The car will start and run. Lights will Likely work. The ammeter will read backwards. If you know it’s hooked up negative ground, I would just reverse that connection and be done with it. 
Ron Hausmann P.E.