MTFCA Forum

I was doing a lot of starts and stops lately. So the battery is to low to start it. I'm charging the battery right now but, if some reason it won't crank can I use a 12v jump to just the starter?Thanks

I wouldn't do it. Applying 12 volts to the starter risks damaging the starter drive. Applying 12 volts to a 6 volt system with the battery in place risks damage to the battery and other parts of the system and perhaps to the 12 volt system. If you're thinking of running your T without a battery, don't, unless you ground the generator first. Ground the generator output terminal, not the cutout terminal. The car should start on BAT with the hand crank even if the battery is too low to crank the engine. It should start on Mag with the hand crank regardless of the condition of the battery. (Emphasis on "should")

A 12 volt battery can be used to start a 6 volt. But should something go very wrong, remember you made the choice to use the 12 volt parallel to the 6. As for what could go wrong: 1. throwing solder from the starter, 2.an explosion, or 3. even a fire. For me, I learned after the battery exploded (spark and battery off gassing) and as the battery case split, the acid from the battery exploding does indeed burn the skin.

This was common practice in the 1950s during the transition from 6 volts to 12 volt systems in cars.
I made the mistake of doing this with my model t about 40 years ago when I had trouble getting it started. Later when I remove the starter, the drive spring was badly distorted. Just keep things in good shape and 6 volts will do the job.
Art Mirtes

This was common practice in the 1950s during the transition from 6 volts to 12 volt systems in cars.
I made the mistake of doing this with my model t about 40 years ago when I had trouble getting it started. Later when I remove the starter, the drive spring was badly distorted. Just keep things in good shape and 6 volts will do the job.
Art Mirtes

If you do it, don't use the button.
Connect the + to the starter's terminal, then 'flash' the - onto the starter casing - unless it's got a thick coat of paint. If so, find a nearby bolt head.

Ref all those warnings about damaging the starter; lots of people run their Ts on 12v without making mods to the starter and seem to get away with it. (But I'm staying with 6v!)

I haven't been out to check if the battery is up enough but, this is a temporary fix. Not planning to use it often.

It's not a good idea, and can lead to a lot of trouble. I'd use the crank, or charge the battery. Your generator charging rate can be adjusted, if needed. An old weak battery will give headaches from now on. Replace if needed. Starter damage repair on a T can be a pain.

PS: Any damage will be permanent until repairs are made. I would not risk breaking things without some compelling reason, such as an emergency.

I am not sure what you mean by "starts and stops", but if you mean such as driving down to the corner store and back or to the gas station and back, one thing you can do is to use the starter when the engine is cold, then after a short stop, it should start easily with the crank. So you can save the battery about half of your starts. Another thing which would help is to set the generator up to charge more so it would restore the charge faster. If you do most of your driving during daylight hours, and you are taking a longer drive, put the lights on. Just remember to turn them off when you stop the car.
Norm

Thanks for all the replys, went out this morning after on the charger all night, it started right up.

Running the lights during an extended daylight run will prevent overcharging the battery. Adjusting the charge rate so that it will maintain 2-3 amps charge with the lights on going about 20 MPH should work OK. That would probably give about 10 to 12 amps with the lights off at 20 MPH. A small pilot light on the dash that indicated that the headlights were on would be a nice feature. The generator will consume some horsepower any time it is charging. I'm guessing a 10 amp load would absorb about 4/10 horsepower. That could be offset by adding 2 PSI to your tire pressure or shedding any un-needed weight.

Yes, My speedster has had the same original starter (unmodified) running on 12v for over 40 years. On the speedster I built in HS I ran a stock unmodified starter and the only problem I had was once I forgot to retard the spark and broke the spring. My 38 Lincoln is runnin the stock starter oon 12v.

I do It all the time. And have never had a problem. You can can even use your DC welding machine to jump a car.