Polarity of battery
Forum rules
If you need help logging in, or have question about how something works, use the Support forum located here Support Forum
Complete set of Forum Rules Forum Rules
If you need help logging in, or have question about how something works, use the Support forum located here Support Forum
Complete set of Forum Rules Forum Rules
-
Topic author - Posts: 14
- Joined: Wed Feb 27, 2019 10:17 am
- First Name: Melchior
- Last Name: Pons
- * REQUIRED* Type and Year of Model Ts owned: 1916 speedster
- Location: Amsterdam
Polarity of battery
I picked up this 1926 roadster last week. It came without a battery. I’ve read here that model T is negative ground. The battery clamps however suggest that mine is postive ground (one connector is slightly bigger).
I hooked it up as negative ground. Engine starts, if I switch on the headlights, amperes go into minus, so it seems that I have done it correctly. I cannot imagine that an engine would start in opposite direction?
Is there another way to check?
Thanks!
I hooked it up as negative ground. Engine starts, if I switch on the headlights, amperes go into minus, so it seems that I have done it correctly. I cannot imagine that an engine would start in opposite direction?
Is there another way to check?
Thanks!
-
- Posts: 3299
- Joined: Sun Jan 06, 2019 10:56 am
- First Name: Dan
- Last Name: Treace
- * REQUIRED* Type and Year of Model Ts owned: '23 cutoff, '25 touring, '27 touring
- Location: North Central FL
- MTFCA Number: 4838
- MTFCI Number: 115
- Board Member Since: 2000
- Contact:
Re: Polarity of battery
The Ford Model T 1919-1927 is negative ground. Seems a lot get confused today as the 1928 Model A was positive ground.
Battery posts on 6v storage battery are different sized to keep from mixing up. The positive post is the larger post.
Battery posts on 6v storage battery are different sized to keep from mixing up. The positive post is the larger post.
The best way is always the simplest. The attics of the world are cluttered up with complicated failures. Henry Ford
Don’t find fault, find a remedy; anybody can complain. Henry Ford
Don’t find fault, find a remedy; anybody can complain. Henry Ford
-
- Posts: 140
- Joined: Sat May 30, 2020 9:54 pm
- First Name: Jim
- Last Name: Forbes
- * REQUIRED* Type and Year of Model Ts owned: 1927 Coupe
- Location: Sierra Vista AZ
- Board Member Since: 2020
Re: Polarity of battery
If you are only familiar with permanent magnet type DC motors, then you would be right. In a permanent magnet motor, when you reverse the polarity of the armature, the magnetic flux in the armature changes direction. Since the field is permanent magnets, they keep their previous direction of magnetic flux, and the motor then runs backwards. But this is a series would motor,it has electromagnets for both the field, and the armature. That means that when you reverse the polarity, you will make the magnetic flux go the opposite direction, in both the field, and the armature. Since they are both reversed, the result is that the motor always turns the same direction.
Negative ground for the Model T.
-
- Posts: 5412
- Joined: Tue Jan 08, 2019 4:56 pm
- First Name: Frank
- Last Name: Brandi
- * REQUIRED* Type and Year of Model Ts owned: Speedster (1919 w 1926)
- Location: Moline IL
- Board Member Since: 2018
Re: Polarity of battery
Why didn't you swap the the contacts on the ammeter too? Have you checked the cut-out polarity?
The past is a great place and I don't want to erase it or to regret it, but I don't want to be its prisoner either.
Mick Jagger
Mick Jagger
-
Topic author - Posts: 14
- Joined: Wed Feb 27, 2019 10:17 am
- First Name: Melchior
- Last Name: Pons
- * REQUIRED* Type and Year of Model Ts owned: 1916 speedster
- Location: Amsterdam
Re: Polarity of battery
I did not do anything to the car. I am just wondering if there was another way of checking. Cutout? I do think that if the ammeter goes into negative when I switch on the lights polarity is correct, or am I wrong? Plus, what damage can it do?
-
- Posts: 4072
- Joined: Tue Jan 08, 2019 1:39 pm
- First Name: Norman
- Last Name: Kling
- Location: Alpine California
Re: Polarity of battery
Don't swap anything! The ammeter goes to negative with the lights on. That is correct. If your generator is working and the lights are off, the ammeter should go to positive. If so, everything is OK. With the lights on, your and the engine running, the lights on would go to negative at idle, and then go toward zero with the engine running faster. How far would depend on the adjustment of the generator. If you do most of your driving with the lights off, set it to less than 5 amps, but if you drive with the lights on, then adjust to where it is just above zero with the lights on and going about 20 mph. Note, if you have it adjusted for driving with lights on, than when you drive for distances over a mile or two with lights off, turn them on so you do not overcharge the battery. Some T's use an after market voltage regulator. If so, it should take care of the change from lights off to lights on by itself. I don't use one because I very rarely drive after dark if I can help it because of the slow speed and lack of visibility to other drivers. I live in a rural area so there are dark winding roads here, but if you live in a city with street lights and you wish to go to dinner or other night driving, it would be safe to do so.
Norm
Norm
-
- Posts: 5412
- Joined: Tue Jan 08, 2019 4:56 pm
- First Name: Frank
- Last Name: Brandi
- * REQUIRED* Type and Year of Model Ts owned: Speedster (1919 w 1926)
- Location: Moline IL
- Board Member Since: 2018
Re: Polarity of battery
Sorry, I misread what you said. Since everything appears to function correctly its likely that the wrong cable was used and that is causing all the questions. The cut-out sits on top of the generator and its purpose is to disconnect the circuit to the battery when the engine is off so the battery doesn't run the generator as a motor.
The past is a great place and I don't want to erase it or to regret it, but I don't want to be its prisoner either.
Mick Jagger
Mick Jagger
-
- Posts: 945
- Joined: Sun Jan 06, 2019 5:39 pm
- First Name: James
- Last Name: Golden
- * REQUIRED* Type and Year of Model Ts owned: 1926 Model T Roadster
- Location: Bowie, MD
- MTFCA Number: 14294
- MTFCI Number: 13562
Re: Polarity of battery
Henry Ford (actually Edsel was in charge by then) switched the Model A to a Positive + Ground and the polarity remained that way for quite a few years.
No one has ever found or published a reason for the change.
No one has ever found or published a reason for the change.
-
- Posts: 663
- Joined: Fri Jan 04, 2019 11:15 am
- First Name: Tony
- Last Name: Bowker
- * REQUIRED* Type and Year of Model Ts owned: 1914 touring
- Location: La Mesa, CA
- MTFCA Number: 32
- MTFCA Life Member: YES
- Board Member Since: 2005
Re: Polarity of battery
The supposed reason to use the positive ground was to reduce the corrosion at the battery terminals.
This is the story I was told, personally I think it’s a load of nonsense. JMHO
This is the story I was told, personally I think it’s a load of nonsense. JMHO
Tony Bowker
La Mesa, California
1914 Touring, 1915 Speedster, 1924 Coupe.
La Mesa, California
1914 Touring, 1915 Speedster, 1924 Coupe.
-
- Posts: 1045
- Joined: Sat Apr 13, 2019 6:06 pm
- First Name: Susanne
- Last Name: Rohner
- * REQUIRED* Type and Year of Model Ts owned: Late '15 touring, "Angel".
- Location: Valfabbrica, (central) Italy
- MTFCA Number: 464
- MTFCA Life Member: YES
- Board Member Since: 1999
- Contact:
Re: Polarity of battery
Had to do with the current (no pun intended) electrical theory at the time. The thought was (for a while) that juice went from Negative to Positive, so they were still putting the swith on the supply side by having positive, not negative, grounded.
I also heard from an old british iron mechanic that it created more corrosion issues at the switch. Not sure how or why, but I so know + earthed Lucas electrical systems tend to leak more smoke than their American counterparts, and do have connector and switch issues.
Anyway... A T came from the factory as a negative ground car. True, you can flash the generator and change the cutout (or regulator) to be positive ground (like a Model A - maybe they did this to use the newer parts in a T, I don't know), but you have the problem that, by modern convention, you go to jump the car and you pop and fry stuff by hooking it up backwards.
I also heard from an old british iron mechanic that it created more corrosion issues at the switch. Not sure how or why, but I so know + earthed Lucas electrical systems tend to leak more smoke than their American counterparts, and do have connector and switch issues.
Anyway... A T came from the factory as a negative ground car. True, you can flash the generator and change the cutout (or regulator) to be positive ground (like a Model A - maybe they did this to use the newer parts in a T, I don't know), but you have the problem that, by modern convention, you go to jump the car and you pop and fry stuff by hooking it up backwards.
-
- Posts: 584
- Joined: Tue Jan 08, 2019 12:25 pm
- First Name: Jim
- Last Name: Davis
- * REQUIRED* Type and Year of Model Ts owned: 1926 Touring. 1923/26 Open Express. 1920 depot hack
- Location: Tomball,Texas
- MTFCA Number: 49832
- MTFCI Number: 24686
- Board Member Since: 2017
REVERSE CHARGE
The person who gave You the jump is not happy either. You can reverse charge a battery. AX Me how I know.