What is the correct Group Number for a T owner that wants to upgrade from 6 Volts to 12 Volts and have the battery fit in the same original space?
Interstate used to list the Group Numbers on their website with specifications, but it is hidden or missing now.
I'm guessing group 2. Would you stay with the top terminals in the opposite sides of the battery like the 6v so your cables stary the same? Or would you go to maintainance free and side terminals and the thinner gage cables as well?
Check the NAPA site for possible dimensions of group sizes.
Good luck with your transition.
Maybe this will help. I got my 6v from Tractor Supply and it fits perfectily, but I built my wooden box around it, so I don't have the actual dimensions of the original Model T batteries.
Perhaps this chart will help...
Why not just measure the space and take the numbers shopping?
Why "upgrade" to 12 volts? Make sure your wiring is of adequate size and all terminals are clean and tight. I assume your coils are in good condition. I have read that the only reason for the change from 6 volts to 12 was to reduce cost. I can't tell any difference in the performance of my car on 6 0r 12 volts. Of course I run on mag.
Dumb idea. Stick with 6 volts.
Ever consider an 8 volt battery? They are available from a lot of farm supply stores. Should be able to leave your generator and starter without modification.
I just get the cheapest 12 volt car battery. I think its for a Toyota Corrola, 200 model year. It will fit in a T battery carrier just fine, or under the back seat if the car was not battery equipped originally.
I didn't beat the dead horse before about 12 volts not being an "upgrade", but it isn't. At least not for starting. Some argue that it improves lighting and permits use of modern accessories. Those may be valid considerations. But for starting, twelve volts (or eight) is a waste of time and money.
I agree, 12 volts is a downgrade. The six volt system works great, is authentic and the correct sized battery is cheap and readily available at TSC and elsewhere.
Steve, there are no valid considerations for a 12 Volt battery, if you have a good 6 Volt battery and the correct size 0 or 1/0 gauge cables.
This car was purchased with a 12 volt system and a Mitsubishi 12 Volt alternator. The reason was given as it had a distributor and no magneto installed, for a lighter flywheel and better acceleration. It also has a Model A crankshaft.
I recently learned the 1928 Model A was manufactured with 00 or 2/0 gauge battery cables, until mid 1928, when it went to the 0 or 1/0 gauge cables.
I just got back from Walmart with him and a new battery for him. The one he took out was a Group 35. He claimed it was 14 years old, but the sticker on the side said it was manufactured in 2013.
We measured the Group 1 6 Volt battery and the Group 35 and Group 86 12 volt batteries while there.
The cases were all the exact same size and all had top terminals. The Group 1 battery has the terminals staggered on top. The Group 35 battery has the terminals on the same long edge with the + on your right when looking at the battery with the terminals closest to you. The Group 86 has exactly the same top configuration, except the + and - terminals are reversed.
So Walmart answered our battery questions, but the need is still rather vague.
The op has weighed his/her options and is looking for information on 12v battery sizes, not questioning the wisdom of doing so. It's his/her T and they can do what they want.
Having said that, going through the same decision making process on my WWII jeep, to elave it standard 6v or "upgrade" to 12v during the restoration, I decided to leave it 6v. Yes, it needs every one of them to start, but with good ground straps and cables and running well, it gets the job done. However, it id does die during an event, I am hard pressed to get a jump for my 6v.
Difficult to find a home charger for 6v and darn near impossible to find one of the prtable charging stations for 6v.
A group 26 twelve volt battery is about the smallest automotive 12 volt made. I know it will fit as I have used them. On a restored car (like my Grandfather's) I'd stick to 6 volts, however on a driver or tour car I have no problem going to 12 volts (I have). The charging and starting systems must be modified. A 12 volt alternator or generator and a 12 volt starter are a must.
James, thanks for the clarification. Since the change has already been made I agree with you to leave as is.
12v vs 6v starting . . .
12v vs 6v lighting . . .
12V vs 6v charging . . .
12V vs 6v accessories . . .
I supose the question becomes how much do you drive your car and how inconvienced do you want to be getting replacement anything. On our model A we switched from 6 to 12 but then we were putting 1-300 miles a week on the car.
I find that ohm's law is still valid.
No difference between 6 and 12 when running on MAG of course, but when running on BATT 12V does give a "upgrade" in power compared to 6V.
Note that outside the USA a 6V battery is not easy to find.
You can get a group 1, 6 volt battery from Auto Zone. They are good batteries.
To "upgrade" to 12 volts you need to change the starter or change the wiring inside the starter. The generator will charge 12 volts, but most users switch to an alternator.
The car will run on the Ford ignition coils on 6 volts if the coils are tuned to run on 6 volts. They run best on the original magneto.
If you use a distributor, you can get a coil made for 6 volts and you will not need to change the battery.
All the light bulbs will also need to be changed if you use 12 volts.
The 12volt case sizes are here or in any current SAE standards book.
Note that adding F to the case size swaps polarity since the posts are no longer diagonally opposite and symmetric.
I agree with many of the other posters and am committed to six volts. I recently removed an eight volt from a newly purchased car and installed correct wiring so it works as designed.
Has any one set up to start with two 6 VDC batteries in series? See the diagram.
Reminds me of eBay auctions, selling antique cars that have been "upgraded" with a "modern" drive train.
Interesting how people cherry pick which changes "corrupt" an antique car, and which do not.
If 12V is a "sin" wouldn't using modern detergent multi-grade motor oil, or using black rubber tyres (rather than white), or using alloy pistons, also all be sins?
(Message edited by m2m on February 15, 2017)
(Message edited by m2m on February 15, 2017)
I've run a model T and model A starter on 12V with no problems. On my mom's speedster the starter has been running on 12V for decades. The weak point is the bendix spring so you must always remember to retard the spark. On my '12 I will be using a small 12V battery for coil starting (had crank) simply due to leaving me the option should I desire to install small 12V LED bulbs for signals etc.
Constantine - 6 V batteries are easy to find anywhere in the world where there are antique auto hobbyists - German car manufacturers like Opel, Ford and VW didn't swap to 12V until 1967, while the US manufacturers did the swap earlier or by the mid 50's.
I think the only valid reason to swap to 12 V in a Model T is if you use coils and haven't got a functioning magneto. Then 12V would give almost the same power on bat as a functioning mag gives.
But otherwise, it's unnecessary. And remember - there's no reason to change to an alternator just because you want to go 12V - the original generator can charge 12V too. Still about 90W max, so less amps needed or about 7.5 A max at 12V.
I use 12 volt batteries because they are cheaper. I don't even have a starter on my '10. None of my T's have a charging system. The 12 volt batteries are great because I can buy light bulbs anywhere, and if a battery ever goes bad then one of those can be had anywhere.
I don't typically use the starter in any of my T's that have starters, but have never had one fail or heard of one causing damage due to being powered by 12 volts. Its one of those things - you can't prove something doesn't exist.
Since my work is snow covered and I am stuck at home today I have been following this thread with interest. I noticed on this thread and have heard many other times that a 12 volt system produces a stronger spark than does 6 volts. When the spark occurs the battery or mag is completely out of the coils circuit. The coil armature pulls in at a given current and this current has built up a magnetic field around the iron core. When the armature pulls in it breaks the current flow to the primary circuit. The rapid collapse of this magnetic field induces a voltage in the secondary coil. which fires the plug. Therefore the spark at the plug is independent of battery voltage. I once tried 12v and 24 volts. I couldn't tell any difference. By current I mean AMPS not volts. I could be wrong.
Harry - the problem with the 8 volt is finding a decent charger. I run an 8-volt in one of mine (all the rest are 6-volt) and the only charger I could find was some cheaply-made one on the internet that does not work well.
Lenney - it's not about the strength of the spark, it's about how fast it's created. When running on "Bat" on 6v, the coils tends to be slower to create the spark after the timer grounds them. That's no problem at slower rpm:s, but at higher speeds there's not enough time to create the spark, so it comes too late. A 12V battery excites the coil faster so that it works almost as good as with the magneto. My comment concerns Model T coils calibrated in the usual way to work at both mag and bat, though I know John H in Australia has tweaked his coils to work at higher speeds too at 6V, but then they won't work as good in a mag equipped car.
Here's a diagram showing the difference in performance, where 6V on bat is lower than 12V on bat and Mag, which are hard to tell apart:
Roger, thank you for the information. Yes on 6 volts at high rpm the commutator would outrun the coil saturation time. However I have never noticed this since my tee would fly in pieces if I ran those rpm's. I think my tee tops out at about 2000-2200 rpm's
Using to six volt batteries involves finding space for the second battery and all the complicated wiring. Antique Auto Battery Co., who manufacturers authentic batteries for a lot of vehicles, makes a 12 volt battery with a third post in the middle that provides the user six volts and twelve. I don't know if they will fit in a Model T battery carrier.
One supposed reason for changing to 12V isn't really a reason; Most, if not all, GPS and cell phones will charge on 6V too. Just hide a cigar lighter socket, connect to 6V and plug the charger - maybe it'll only charge when the engine runs and the generator is charging, but it'll usually charge
This comment does not address the original question, but I'll stick my neck out here....
For Popeye, I opted to remain with 6 volts. I bought the Optima red-top battery. It's very compact, so much so that I had to 'shim' the battery inside the battery box I built.
The Optima has a LOT of cranking power and I have not been able run it down. Good guarantee on it, as well.
Just my 2-cents worth....
Cliff I am surprised you bought a Battery for Popeye. He had a 60 day old Tractor Supply Group 1 that cost $90 when I sold him to you. Did that battery fail?
Hey Royce! Yes, the battery would not hold a charge, even after 24 hours on the charger (6-volt, of course). I took it to my Ford dealership, they tested it for me and it failed.
Maybe the trip from Dallas to DC took a toll?
FWIW, I cannot recommend the Optima enough...
That is what I was looking for and could not find.
Now I need to find the 6 volt chart.
My car came with an 8 volt battery and being underneath the trunk floor does not provide an easy access.
I decided to check the cell water level and was surprised to find 4 caps to check.
That was about the same time my Bendix spring broke.
I replaced the 8 volt with a new 6 volt battery and new 00 or 2/0 gauge cables.
Then the engine started better and quicker than it had with the 8 volt battery.
That was 15 years ago and the new Bendix spring is still working fine.
The other Bendix spring was wound the wrong way and that may have caused the break, rather than the extra volts.
Nobody has mentioned this, but the OP mentioned a "Group 2" battery--the group 2 is a 6 volt battery--a bit larger than the group 1--it's what my old '39 Ch@#@y used.
I use 12v lawn garden type
Cheap and small
But then I not a starter guy so that not an issue but I probly got the only T with a USB port hidden
For that 21 century period accessories
Roger, would you please explain the diagram. I can't make sense of time(in seconds ?) or the correlation of mph and rpm. The title indicates a voltage comparison, but voltage is not indicated. I realize that your knowledge of Tee coils is well above us average Tee'rs. Thank you.
Lenney - I'm no coil expert, just trying to digest some of the info that flows from the experts here at the forum
The diagram was done by Mike Kossor while testing performance of coils adjusted by his E-tester and it shows a Model T accelerating from 0 to 32-33 mph in just under 30 seconds. The Mph is shown to the left. At the same time, the diagram shows engine rpm on low and second gear as it accelerates, the rpm is shown to the right. All three alternatives are shown, so you can see the car won't rev higher than 2000 rpm in low on 6V bat before it's time to go to high, and thus the acceleration is slower than on 12V or mag, where the engine revs up to almost 2300 rpm before shifting.