Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 06-15-2024, 11:15 PM   #1
Ezombie
Junior Member
 
Join Date: Dec 2012
Location: Arizona
Posts: 2
Default Canít determine battery ground

I recently acquired in 1929 tudor that has been stored for 40 years. It was a running car when stored but someone has removed the battery so I have no way to know whether it is a standard positive ground or a negative ground system. Is there an easy way to determine this with no battery present?
Ezombie is offline   Reply With Quote
Old 06-15-2024, 11:40 PM   #2
Charlie Stephens
Senior Member
 
Join Date: May 2010
Location: Southern California
Posts: 7,089
Default Re: Canít determine battery ground

Install the battery using your best guess. Note the positive post is slightly larger so that might be a clue. Turn on the lights. If the ammeter goes positive you have it backwards.

Charlie Stephens
Charlie Stephens is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 06-16-2024, 06:57 AM   #3
nkaminar
Senior Member
 
nkaminar's Avatar
 
Join Date: Jan 2012
Location: Western North Carolina
Posts: 4,244
Default Re: Canít determine battery ground

The connectors for the battery terminals are different sizes. I forget which one is slightly larger. Try to fit the connectors and if they do not fit reverse them and try again.
__________________
A is for apple, green as the sky.
Step on the gas, for tomorrow I die.
Forget the brakes, they really don't work.
The clutch always sticks, and starts with a jerk.
My car grows red hair, and flies through the air.
Driving's a blast, a blast from the past.
nkaminar is offline   Reply With Quote
Old 06-16-2024, 07:03 AM   #4
Bob Bidonde
Senior Member
 
Bob Bidonde's Avatar
 
Join Date: May 2010
Location: Long Island, NY
Posts: 3,586
Default Re: Canít determine battery ground

It does not matter which ground polarity you decide to run with. After the many years in storage, the generator lost its residual charge. However to be authentic, hook the battery positive terminal to the frame cross-member. After a few minutes of running, the generator will remember the ground polarity you selected.
__________________
Bob Bidonde
Bob Bidonde is offline   Reply With Quote
Old 06-16-2024, 08:57 AM   #5
Rob Doe
Senior Member
 
Join Date: Apr 2021
Location: Central Illinois
Posts: 552
Default Re: Canít determine battery ground

Are you installing a 12v or 6v battery. If 6v, install as positive ground to the x member. If the car was set up as 12v, negative, the ammeter wires will have been reversed????
__________________
"It ain't what you know for certain that gets ya in trouble. It's what ya know for certain that just ain't so!"
Rob Doe is offline   Reply With Quote
Old 06-16-2024, 11:50 AM   #6
nkaminar
Senior Member
 
nkaminar's Avatar
 
Join Date: Jan 2012
Location: Western North Carolina
Posts: 4,244
Default Re: Canít determine battery ground

Sponsored Links (Register now to hide all advertisements)
Rob Doe brings up a good point. Do you know if it was 12 volts or 6 volts? One way to check would be to take a bulb out of the tail light and hook it up to a 6 volt battery. If it is dim then the chances are that the car had a 12 volt battery. If you hook up the bulb to a 12 volt battery and it burns very bright or burns out then it was a 6 volt battery.
__________________
A is for apple, green as the sky.
Step on the gas, for tomorrow I die.
Forget the brakes, they really don't work.
The clutch always sticks, and starts with a jerk.
My car grows red hair, and flies through the air.
Driving's a blast, a blast from the past.
nkaminar is offline   Reply With Quote
Old 06-16-2024, 12:22 PM   #7
stevests
Senior Member
 
stevests's Avatar
 
Join Date: May 2010
Location: Longbranch, Washington
Posts: 533
Default Re: Canít determine battery ground

Aren't most light bulbs marked for voltage or check the number if still visible ?
stevests is offline   Reply With Quote
Old 06-16-2024, 02:06 PM   #8
Jim/GA
Senior Member
 
Jim/GA's Avatar
 
Join Date: May 2010
Location: Young Harris, GA
Posts: 1,859
Default Re: Canít determine battery ground

Any car that has been stored for 40 years will still be 6 volts.

The post size is a good clue. I suspect positive ground. Most people were happy to leave the cars positive ground 40 years ago, there was no incentive to reverse it.

Hooking it up backwards from how it is intended to be will reverse the polarity on the coil, which will give a weak spark. The engine will start, but you will want to confirm the polarity of the coil. The starter, the bulbs, even the generator will not care about the ground.

I recently worked on a car with the coil polarity reversed. The plugs were fouled. The owner was complaining of lack of power (which it should not have been -- the engine was a fresh rebuild with HC head).
__________________
Jim Cannon
Former MAFCA Technical Director
"Have a Model A day!"
Jim/GA is offline   Reply With Quote
Old 06-16-2024, 06:10 PM   #9
ModelA29
Senior Member
 
ModelA29's Avatar
 
Join Date: Sep 2022
Location: SoCal
Posts: 672
Default Re: Canít determine battery ground

Quote:
Originally Posted by Jim/GA View Post
Any car that has been stored for 40 years will still be 6 volts.
Any car stored 40 years ago with a generator is probably still 6 volts.
Any car stored 40 years ago with an alternator is probably 12V.
ModelA29 is offline   Reply With Quote
Old 06-17-2024, 06:30 AM   #10
nkaminar
Senior Member
 
nkaminar's Avatar
 
Join Date: Jan 2012
Location: Western North Carolina
Posts: 4,244
Default Re: Canít determine battery ground

Any car stored 40 years ago will need more than a battery. The air in the tires is very old and needs to be replaced.
__________________
A is for apple, green as the sky.
Step on the gas, for tomorrow I die.
Forget the brakes, they really don't work.
The clutch always sticks, and starts with a jerk.
My car grows red hair, and flies through the air.
Driving's a blast, a blast from the past.
nkaminar is offline   Reply With Quote
Old 06-17-2024, 10:05 AM   #11
Bruce of MN
Senior Member
 
Bruce of MN's Avatar
 
Join Date: May 2010
Location: VA
Posts: 1,467
Default Re: Canít determine battery ground

That Ď80ís air was pretty good, so Iím not sure about that.
Bruce of MN is offline   Reply With Quote
Old 06-17-2024, 12:30 PM   #12
Jim/GA
Senior Member
 
Jim/GA's Avatar
 
Join Date: May 2010
Location: Young Harris, GA
Posts: 1,859
Default Re: Canít determine battery ground

It would be nice if the Original Poster came back with what they found, photos, etc. Otherwise we are all just wasting our time.
__________________
Jim Cannon
Former MAFCA Technical Director
"Have a Model A day!"
Jim/GA is offline   Reply With Quote
Old 06-18-2024, 10:23 AM   #13
rotorwrench
Senior Member
 
rotorwrench's Avatar
 
Join Date: Jun 2010
Location: San Antonio, Texas
Posts: 16,643
Default Re: Canít determine battery ground

Look for a ballast resistor connected to the coil. 12-volt conversion would require that on an original type 1.5 Ohm primary type coil. If the coil is modern then it could be a 3-Ohm type for 12-volts.

40 years dates back to 1984, A lot of stuff was available back then. The generator could tell a bit if it still has one. The converted GM 10si alternators were available in 1984.
rotorwrench is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 07:53 PM.