12 volt Motel T

You would likely need a separate battery for the coils during start or a ballast to cut the power back. Once its on the magneto it would be isolated. I would rather carry a small 12-volt battery to power some accessory than the other way around. The computer back up type batteries are small and light weight and last a long time with regular charging.
 
The coils will like it just fine. The magneto puts out up to around 36 volts (AC). With 12 volts, the ramp up time is faster. While the coils will work fine on 6 they work better on 12, should give you a faster top end. (meaning, with 6 volts the T is slower to reach its potential speed around 35+/- but it will get there. 12 volts should get you there faster) Coils don't care if starting on 6 or 12.
 
Coils can do the same thing if left buzzing on 6 volts. 6 or 12 they still have a draw of 1.2 to 1.4 amps.
It's a heads up not don't do;
"The coils can take 12 volts no problem, the magneto produces more then the 12 volts when going down the road. The only thing you have to watch out for though is when you start the car and have one of the coils buzzing before turning the engine over. when the coil is in a constant fireing loop like that it heats up, and the 12 volts will have it heat up quicker then on 6 volts. So just dont let the car sit in that constant firing loop more then it needs to be."
People have been running and starting the cars on 12 volts for years.
 
I assume that would happen if the timer was stopped at any particular terminal prior to starting with the switch on too long. That makes good sense to me now.

The same thing can happen to a more modern breaker ignition if the ignition switch is left on with the breaker points in the closed position. The coil will fry itself if left that way overnight plus the battery will be dead as a door nail. There is no buzzing to warn a person.

We use the Bendix TCM starter vibrators on the helicopters. They were marketed as the "shower of sparks" and are activated when the magneto retard points are open on any given spark plug during the starter function. They buzz just like a T coil but you can seldom hear it due to the starter turning and its associated noise. They really help on the higher compression engines and especially when it's cold out.
 
Been using 12 volts in Model T's forever, never had any issue with starters or starter bendix or any other problem. The key is to use smaller diameter wire on the positive cable. Two of my t's have 4 gauge cable, 12 feet long, to connect the battery to the starter solenoid. This makes a considerable voltage and current drop at the starter. They sound like a 6V starter.


I have taken apart T engines that never had a 12 volt battery and found all the teeth bent over on the ring gear, or blown up starter bendix, and worse. What damages them more than anything is starting the car with the spark advanced too much.
 
I have used 12 volts in Model T’s and A’s for years. On one of my T’s the mag is dead so it only runs on a twelve volt battery. The only thing I have noticed is the coil points start to have some build up on one side, so one season I run it negative ground and the next positive ground. It seems to cut down on that issue.
The car is hand crank so no bendix problem. My other T is electric start and so is one of the Model A’s. I never thought of using a smaller diameter wire to cut down voltage. I have always taken an old bendix spring and hooked it to the starter terminal and then hooked the battery cable to the other end of the bendix spring it cuts the voltage down nicely.
 
Royce,
I'll be putting my electrical system together soon. I decided to go 12 volts, putting the battery under the back seat of my touring. I thought I'd run #4 from the battery to the starter and a friend suggested I put an old bendix spring in series with the #4 near where it connects to the starter. Based upon your experience, do I really need to install the spring? I'm using a small AGM battery capable of 365 cold cranking amps.



Tim
 
The spring is an ad hoc type of installation and would act as a resistor so it will get hot during start phase. It would also have to be insulated to prevent short out. Who knows what resistance it has. It would function just like a heating coil. It might work OK but I think I'd look around to find a more calculated way of doing the same thing another way.
 
I have run my 1914 Touring for years on 12 volts. When I got the car I rebuilt the coils with modern condensers. No starter, it is hand cranked. I wouldn't think of using the car after sunset. My mag does work but many times I forget to make the switch from the battery. I like the 12 battery because it is a stronger, longer life, cheaper battery than the 6 v. Ed
 
I've never used a bendix spring like that.




Oldav8tor said:
Royce,
I'll be putting my electrical system together soon. I decided to go 12 volts, putting the battery under the back seat of my touring. I thought I'd run #4 from the battery to the starter and a friend suggested I put an old bendix spring in series with the #4 near where it connects to the starter. Based upon your experience, do I really need to install the spring? I'm using a small AGM battery capable of 365 cold cranking amps.



Tim
Click to expand...
 
Some of the guys in the Spokane club run the spring on the battery ground. No energized spring to insulate. I'm running that set up on one of my 12v cars, works fine. Just another approach.
 
I use a 12 volt battery with small cables to the starter when I start my T because my Big LED stop lights require 12 volts and it is the easy way. I drive the car on the mag. But could run it on 12 volts.

My Model A is different. It is set up as a 6 volt vehicle (6 volt battery lights etc.) and I added a small 6 to 12 volt transformer for the large stop lights.
 
I have a 22 speedster I put back together in the early 70. The engine does not have the magnets on the flywheel or coils, The stock generator will not keep up with the aftermarket ignition and the lights. after a while the lights go dim and the engine misfires until I turn the lights offI am in the rebuilding process and plan on running 12 V I have read that the starter fields should be rewired to run 12 V .. any one done that,
 
Sounds as though you have generator issues ?


I've had starter fields rewired for 12 volt - fellow in Southern California did them.
 
A Model T generator puts out about 100 watts max. Changing the voltage of the battery won't change that fact. Distributors tend to need about 75% more power to operate than the stock ignition because distributors are not as efficient as the factory ignition system.


Your headlights and distributor ignition combined probably require more power than the T generator can produce. You can install an alternator to get more power. 6V alternators are the same price as 12 volt.
 
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