MTFCA Forum

Has anyone ever installed an 8 volt battery in a 1927 Model T?

I was wondering if it would cause any damage to the electrical components, ie. generator, starter, light bulbs.
Appreciate any insight into this situation.
Thanks Joe g

Why would you want to Joe?

Been running 8V for 20+ years.
All 6v stuff is rated to 8v. Brighter lights, stronger coil spark, stronger electric starting with no damage.
Set generator output down to 4A to be on the safe side.
The only down side is the cost & availability. Interstate battery still sells em.
Charging can be tricky without an 8v charger.

The question wasn't "why?"

I have run 8V and was pleased, coils fire hotter at low rpm. The only downsides I could think of would be that the bulbs burn brighter, therefor hotter, and therefor their lifespan can decrease, and it was hard on the horn I used.

I'm going to stay neutral and say, "Do Whatever Pleases You and Works Best For You". I've run 6 volt, 8 volt, and 12 volt. Not everybody's car's wiring system is brand new and not everyone wants to spend hours trying to diagnose and fix problems that a low 6 volt system can have.

Our 25 touring runs 8 volt. When Grandpa was still alive before I was involved apparently he was having troubles with it running or starting on 6 volts so he converted it to 8 volts. He added a bunch of light bulbs and other jerry-rigged things to the wiring to converted back to 6 volts when it came to lights and stuff.
We're seriously considering right now rewiring the car and either direct wiring it at 8 volts or converting it back to 6 volt.

Steve Jelf wrote: ↑

Fri Apr 11, 2025 3:00 pm

I'm with Jeff. Why? If the vehicle is defective, why not fix it? The six volt system has been good enough for millions of cars, trucks, and tractors.

Steve is correct.
An 8v battery will improve the starting system with a weak starter or excessive voltage loss in the system.
Best to hunt down & fix the real issue.
A 6v system is fine for a stock motor.
In my case, my motor is hi compression & makes electric starting easier. I refuse to convert to 12v.
I have not burned out any of the 6v light bulbs more often.

Interesting that most assume that Joe has a problem with his starting, the question was would an 8v cause any damage, answer is no, go for it, run 3 of my Ts on 8v, never even blown a globe in 17+ years

My 26 touring came with a new 8V battery a rebuilt 1925 engine/trans with oil slingers and no magneto or working generator about 5 years ago. Not what I would have done, but I'm a bit cheap so I have just left it as is, it has worked well and hasn't caused any problems. My son fabricated an eight volt trickle charger, like a battery tender that has kept the battery in good shape. I just leave it plugged in all the time when I'm not driving it. After a decent run it takes several days to reach full charge.

The engine/trans are probably worth what I paid, it runs and drives but there are many other things needing attention which are higher priority than correcting the electrical system.

6Volt systems powered cars for at least 50 years, either positive or negative ground. The important things that gave problems were dirty or loose connections and the changeover to thinner battery cables designated for 12-volt systems..... with the thought that 12-volt cables would carry more power. The thicker gauge cables are necessary to carry the amperage since the 6 volt system works on amperage and is beneficial for everyday system charging and starting power for the engine. Battery amperage capacity, electrolyte strength and level, and the age of the battery has a lot to do with charging and power results.

My '17 touring (with starter) has an 8v. Everything's just happier.

Since we’re on the 8 volt battery subject; where is the best place to acquire one ? And do you use a golf cart 8 volt in your antique car ? I’ve been trying for well over a year to make a 6 volt positive ground battery work in my 1950 Ford - to no avail. Traveller 6 volt batteries from TSC are junk. Been through 3 batteries and 3 starter motors. Found a possible 8 volt at NAPA for $219. Batteries + quit carrying 8 volt batteries and, yes, I’m using 00 cables, bought a new solenoid and triple cleaned grounding surfaces.
Any ideas ?

This one I use in my Ts, same size as a T battery box and original 6 volt battery size.

George House wrote: ↑

Tue Apr 15, 2025 8:00 pm

Since we’re on the 8 volt battery subject; where is the best place to acquire one ? And do you use a golf cart 8 volt in your antique car ? I’ve been trying for well over a year to make a 6 volt positive ground battery work in my 1950 Ford - to no avail. Traveller 6 volt batteries from TSC are junk. Been through 3 batteries and 3 starter motors. Found a possible 8 volt at NAPA for $219. Batteries + quit carrying 8 volt batteries and, yes, I’m using 00 cables, bought a new solenoid and triple cleaned grounding surfaces.
Any ideas ?

Interstate batteries. They sell a large & a small. The small fits a T. Retail about $175.

George House wrote: ↑

Tue Apr 15, 2025 8:00 pm

Since we’re on the 8 volt battery subject; where is the best place to acquire one ? And do you use a golf cart 8 volt in your antique car ? I’ve been trying for well over a year to make a 6 volt positive ground battery work in my 1950 Ford - to no avail. Traveller 6 volt batteries from TSC are junk. Been through 3 batteries and 3 starter motors. Found a possible 8 volt at NAPA for $219. Batteries + quit carrying 8 volt batteries and, yes, I’m using 00 cables, bought a new solenoid and triple cleaned grounding surfaces.
Any ideas ?

Car's with starters should use a "starter battery". These are designed for short, high burst of energy for a starter. "Golf Cart" batteries are designed for long, lower-power discharge to power an electric motor and accessories over longer period of time. Voltage is an issue by itself and doesn't indicate battery type per se

Very interesting Frank. Thanks for the education. I hadn’t considered that. Makes sense tho. Guess I didn’t realize reasonings behind battery design. Still don’t know best Class 1 battery to acquire..

I agree with Steve. And I think this overhead cam thing is just a passing fad.
Craig.

George, is your '50 Ford's generator polarized correctly? They are capable of charging positive or negative ground, and batteries can be reverse-charged. They will work that way, but not like they should. A test light and an ammeter can be used to determine if the system is is polarized correctly. If it isn't, the generator can be correctly polarized by "flashing" it. If the battery is reverse-charged, it will have to be completely discharged, then charged with the correct polarity. It may work OK after that, or it may not. The car's ammeter would need to have the connections reversed, also, if it has been indicating correctly with the system's polarity reversed. '50 Ford cars and pickups usually have good starter/generator function and good reliability of the electrical system.

Experts warn that overhead cams are an existential threat to our Polar Bear.

Hi Pat,
That should save thousands of baby seals because Polar bears eat baby seals. Sorry I can't help it.
Craig.

George House wrote: ↑

Wed Apr 16, 2025 2:12 pm

Very interesting Frank. Thanks for the education. I hadn’t considered that. Makes sense tho. Guess I didn’t realize reasonings behind battery design. Still don’t know best Class 1 battery to acquire..

For what its worth

A Model T is not a modern car so ones thinking needs to be adjusted as to its needs. Many new cards have small drain electric devices that run all the time even when the car is shut off.

Battery selection should consider:
How frequently will the car be driven.
How will it be charged while driving. Cut-out, Voltage regulator, Fun Projects Magneto.
What does it need to power while driving other other than coils and duration of use.
---- Tail lights & headlights filament or LED can have little effect if battery charged while diving & can even help battery live if turned on/off to ---prevent over charging
---Just Coils then "golf cart" battery. Have starter "starter" battery
Infrequent driving or cold winters - smart charger/trickle charger too.

Since there are only 3 Major Battery Manufacturers in the USA (Johnson Controls, Stryten, and East Penn) branding batteries for different retailers its a tie. Cold Crank spec is not the measure to use for a Model T. Reserve Capacity & Ah are good comparisons to Battery Cost

Every battery I have ever bought was from my local farm supply (Farm & Fleet), usually 2- 3 year warranty and never replaced one of theirs
Can buy 3 F&F (Reserve Capacity: 130 minutes) to one Red Top (RESERVE CAPACITY of 100 minutes)

The advantages of the Optima are cleanliness, light weight, and the ability to be mounted in any position. They are also long-lived if handled properly. The one in my T lives under the seat, lying on its side, and it has caused no issues in the several years I've owned the car. It is 12 years old now, and still working well. It is charged by the stock T generator. When I drive over 5 miles or so after using the starter, I turn on the lights to limit the charge rate. With the lights on, the ammeter registers very close to zero.

I found this thread looking into the 8 volt battery question for my Model T. I would love to stay with a 6v system but if you want an original battery setup ( Metal Box Wooden Box and Lid ) then you cant have a normal group 1 battery 6 volt battery, that I know. I dont think it will fit in those boxes. So some if the originality of the model T is lost when you get rid of those things. Its my understanding that the 8 volt battery will fit in those original boxes.

I am biased in some respects because I love to try to keep my Model T as original as possible. For better or worse I like the originality. But this case seems to be a real conundrum. You have to eliminate parts to use the correct sized battery but can keep the correct parts if you swap to 8 volts.

What is the option with the 6 volt Optima battery? I have seen a smaller version turned at an angle in the original boxes. Is there an Optima red top that will fit with the original parts?

Group 1 battery is the one that goes in the Model. T, group two which went in the model A is a little bit bigger and will not fit in the Model T battery carrier...... The Optima 6 volt can be placed in the carrier at an angle......with two mounting boards underneath to raise battery there'd be no interference with the cable uninsulated terminals any contact with the battery holder frame and secured. With the proper gauge cables carry the amperage, the starter will turn over a lot faster. That has been my experience......... P.S. ...... THERE ARE SELLERS OF A BATTERY CASE THAT LOOKS ORIGINAL THAT THE 6 VOLT OPTIMA BATTERY CAN BE PLACED INSIDE AND INSTALLED,... BUT, I REPEAT BUT... WILL NOT FIT IN THE MODEL T BATTERY HOLDER BECAUSE IT IS THE SIZE OF A GROUP TWO BATTERY FOR A MODEL A !!

I thought the Group 1 battery would fit in the metal case but not fit with the Wood Box inside the metal case in a Model T.

The wood case batteries were original. They are not made any longer. There were three sections that held rubberized inserts that had the battery plates and acid..... The present day Group One battery will fit into the carrier that's already on the chassis, held down with metal clips, and may need the wood base to compensate for the height of the battery according to manufacturer.