Conversion to 12 volt system
 

I have been building my 1930 Tudor as original 6 volt system. But I find that the 6 volt battery does not have enough power to spin starter fast enough, consistently enough to be reliable start. When starter does turn over with any speed, the car does start and run fine, the generator showing a little charge on amp meter when running. It is a new battery, but battery is too weak to start the next time needed. I feel that I need to convert to 12 Volt system for the extra power to start. What electrical modifications need to be made for conversion?

Re: Conversion to 12 volt system
 

A 6 volt system should work just fine. Make sure you have a good clean ground. Make sure you have a good ground strap at the battery. Those braided ground straps oxidize over the years and lead to a bad ground. Recently was troubleshooting a friends Model A and it would not turn over, even with a new battery. New ground strap and it spun like a top.

Re: Conversion to 12 volt system
 

As Greg said,
Remove and sand/clean all the battery connections especially the ground at the frame. I like to add an extra ground cable from frame to bell housing/transmission. Also check that the wires are of the correct size, should be at least #1 or 0. You might also want to check that the starter isn't drawing too much and in need of repair.

Re: Conversion to 12 volt system
 

Many threads on here about converting to 12 volts. Do a little search and you will get all the information you could possibly use.

Re: Conversion to 12 volt system
 

I've driven both my A's for over 34 years and never had a single problem with the 6 volt system. You can run your phone and GPS off the 6 volt system as they both only take 5 volts. If it doesn't spin the motor make sure that the battery cables are for the 6 volt system and that the starter isn't bad. Twelve volts are really hard on a 6 volt starter and you could be beside the road with a broken starter spring. Just my thoughts, but I've only been driving a Model A for 38 years.

Re: Conversion to 12 volt system
 

Agree with MrBruce, 12 Volts can be hard on a system designed for 6V. Bent starter shafts come to mind....don't ask me how I know.

Re: Conversion to 12 volt system
 

If you're converting the car to 12 volts, converting the starter is a part of the job. If that is not done, the job hasn't been done properly. Any job done half assed won't be much good IMO. I've done about 70,000 miles in my A since I converted to 12 volts (I did the job properly) and have had no problems, only enjoyed the advantages.

Re: Conversion to 12 volt system
 

My car has been changed over to 12 volt but haven’t owned it long enough to find out how good of a job they did.If you keep the 6 volt system, as mentioned in a previous post, use large cables for battery to starter and ground. Not being familiar with 6 volt systems ,auto parts stores don’t have cables for them as a general rule.

Re: Conversion to 12 volt system
 

David,



You stated that the ammeter is showing a little charge. Besides all the comments about contact resistance and grounding straps, which you should follow up on, you also need to know if the battery is receiving a proper charge. The generator third brush may need adjusting. Check the battery voltage when the battery is being charged. It should be 7 volts or more. Lots of people convert to alternators but a generator should work if nothing is wrong with it and it is adjusted properly. I have found a voltmeter replacement more useful the the ammeter.



A 6 volt car should start just fine if everything is working properly. If you do decide to convert to 12 volts, follow through with converting the starter to 12 volts.

Re: Conversion to 12 volt system
 

ive broken a bendix bolt and it sounds like a hammer hitting to start the turning of the engine. and my points always need cleaning. im thinking of switching back.

Get good at hand starting your car.

Re: Conversion to 12 volt system
 

Re: Conversion to 12 volt system
 

If you're having point trouble then I'd suggest checking the voltage to them, it shouldn't be over 8v. If it is then you have an improper coil which would either need to be replaced with a 1.5 ohm coil or add an in-line ballast resistor to a 3.0 ohm coil.

Re: Conversion to 12 volt system
 

Guess I was one of those who half-assed converted to 12V on my 26 Model T. It's back to 6 volts (full-assed). My main point was to make sure you have a good ground. Otherwise, convert it to whatever you want-you still need a good ground. I see so many crudded up Model A's with crusty battery cables and folks immediately thinking they need to "upgrade" to 12V. Do whatever makes you happy.

Re: Conversion to 12 volt system
 

The main reason I converted was because I am often driving in remote areas where getting a 6 volt globe or coil is out of the question (forget a battery). 12 volt stuff is readily available though. If 6 volts stuff is available, a good system is OK but terminals need to be maintained. I'd use some dielectric grease on all of them.

Re: Conversion to 12 volt system
 

Methinks you have something bass ackwards.

Re: Conversion to 12 volt system
 

Sounds like your battery is toast. A single starting activity should not be draining the battery to the point where it's unrepeatable. Check the aforementioned cables, connections, etc and put that battery on a charger over night.

Keep in mind that it's the battery's cranking amps doing all the work when turning the engine over. Switching over from 6 to 12 volts may not actually result in an increase of cranking amps depending on the battery you purchase, so it's not as simple as that.

Food for thought. If you want to do a little light reading, here's a story I wrote for Hot Rod Magazine rewiring and converting my Model A to 12volts. Hopefully you'll find something useful in the story...

https://www.hotrod.com/articles/upgr...-a-12v-system/

Re: Conversion to 12 volt system
 

How often is "all the time", it's been 30 years, and when the clutch was stuck I used the starter to drive the car out of the garage and to start car in gear to drive, I think the reliability is more attention to small details, I used new bolts and locks, a lot of the used bolts have worn threads that allows them to wobble and come loose
I have 6 v, but because of bright lights and fast cranking I have been told I must have 12v system

Re: Conversion to 12 volt system
 

Converting to twelve volts is a VERY SIMPLE procedure . I allow mine to remain positive ground and no wires need to be changed or swapped . The original style wiring system uses large gauge wire that will carry 12 volts with no problem . It will be necessary to use a resister at the coil if the original style 1.5 OHM coil is used . I prefer to use a three OHM coil for better performance . I use the Pertronix flame thrower three OHM coil and no resister is needed . I use the original generator and set the adjustable brush for a 10 amp maximum charge rate . I use the Fun Projects voltage regulator that takes the place of the cut out . I use the generator for the original look . An alternator will give brighter lights because the alternator will put out more amps than an original generator is capable of producing . The Original starter works well on 12 volts . I prefer to use the modern starter drive for dependability . The generator runs cooler on 12 volts because of the lower amperage setting at the adjustable brush . If original look isn't important , the alternator will put out higher amps for brighter headlamps . I always replace all bulbs .

Re: Conversion to 12 volt system
 

1.5 ohm for 6v and 3 ohm for 12v. It there is too much voltage to points a ballast resistor may be needed.
Thought thats what I said, if it wasn't its what I meant.



My thoughts were that Mike was still using the '12' volt coil, but, upon re-reading his post it appears that he has not switched back to '6'v. So maybe/probably my thinking is/was backwards. Regardless I think he should check the voltage to his points and go from there. If the voltage is correct then there could be a condenser capacity issue.

Re: Conversion to 12 volt system