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View Full Version : Positive and Negitive ground mix



Jay Goddard
07-04-2007, 10:59 AM
I just bought back my 1950 Starlight coupe and in the process of getting it back on the road I re-wired the entire back portion of the car. I now notice that the guy I sold it to has put the negative cable to ground. Do I dare just swap the cable to the correct positive ground? Also, what are the effects on engine performance by having the grounds reversed?

curt
07-04-2007, 11:05 AM
I think the voltage regulator is specific for a neg or a pos ground system. I would suspect the radio may also be specific as to ground. I suspect the amp cables need reversing to keep the amp meter reading correct. There may be other considerations some one elso can help on or correct me.

Tom B
07-04-2007, 02:20 PM
Uh. Regulators are supposed to be "polarized" when installed, or is it the generator that gets polarized. This sometimes is mentioned as needing to be done whenever the battery is disconnected.

The reversing of polarity is something that needs study.

[img=left]http://www.alink.com/personal/tbredehoft/Bothcars.jpg[/img=left]
Tom Bredehoft
'53 Commander Coupe
'60 Lark VI
'05 Legacy Ltd Wagon
All three Indiana built OD cars

curt
07-04-2007, 02:46 PM
Polorize genarator or Voltage regulator, one has a choice. Tom B. if the amp terminals are fine as to reading with a neg ground, then they will stay fine as long as neg ground is ground.

Mike Van Veghten
07-04-2007, 05:51 PM
Jay -

I "personally".....attached the cables on my 54 Champian one day while installing a new battery!!
While I can't say as far as the radio (didn't work before the mishap!)...everything worked fine! Well...the amp gage worked backward...but the engine ran fine, the gas gauge worked fine.
I'd guess the radio might not like being connected backward...but nothing on my car ws hurt by doing this.

By the way...I did swap the cables back to where they are supposed to be...did NOT mess with the regulator...it charges correctly after the mishap all by itself.

How the starter knew which way to turn baffles me...but it started fine also.

First hand experience!!

Mike

studelover
07-04-2007, 07:11 PM
if the system is 6volts pos. and you reverse the cables on the battery
the fans on your blowers will turn backward and the battery will discharge, the amp gauge will read to the left and the radio tubes will blow.I had a shop try to start my stude and ran the battery down, they hook up a battery charger to it and reverse charged my battery, I had to remove the battery and have it discharged and then charged correctly I don't remember if my regulator suffered however I had to send my radio back to florida and have them repair it, it was a am/fm solid state unit with a inverter.

Studebakers forever!

Mike Van Veghten
07-05-2007, 12:17 AM
Studelover -

The battery will discharge??????

NO sir...it doesn't.
As the post above notes...I've done this. During my little battery install gone backward...I connected a multi-meter to the battery while the engine was running...battery connected to pos. ground....the generating system worked just fine...charging a normal amount...low at idle and higher at higher rpm!

Don't believe...try it or..come by..I'll show you on my own car.
But you are "probably" correct on the blower motors..I didn't try the fans.

Mike

gordr
07-05-2007, 01:12 AM
No, the blower motors or the starter won't run backwards. They are series-wound universal motors, and don't care about polarity. They could even run on AC, if the correct voltage were supplied.

OTOH, if you have more recent, permanent-magnet DC motors, like modern power windows, etc., they WILL run backwards.

Gord Richmond, within Weasel range of the Alberta Badlands

John Kirchhoff
07-05-2007, 02:17 PM
I know this has absolutely nothing to do with cars and batteries, but I can see why automotive style electrical systems were orginally positive ground. In a cloud to ground lightning storm, the clouds are negatively charged and the lightning bolt then travels to the positively charged earth. So whether it's us Yanks calling it the ground connection or the Brits calling it the earth connection, it kind of all makes sense. That also makes sense why electronics have positive grounds and the electricity flows from negative to positive. Well, so much for that foray into the world of useless trivia.