12 conversion

[German guy]

Pro's and con's of a 12v negative ground conversion of my 6v positive ground 1930 Tudor? Do I need to do more than change the alternator, coil, lights and relays, and ammeter, and use a voltage converter for the horn? I have already switched the starter motor located fuse to a circuit breaker on the firewall and added fuses to all of the light systems.



Why do I want to do this? I get rather nervous when that 6v battery sounds like it barely turns the engine over. It has always started but it always sounds like it will not. If a $1000 worth of parts will end that I am up for a few hours of work to make it happen.


Also...with the battery in the stock location it is a pain having to lift the carpet and floor board panel to use a battery trainer and keep the battery fully charged when not being driven often. Perhaps an alternative location such as the running board? I have a red top battery...which has a thinner profile than normal but it will not fit behind the rear seat (I have a three door Tudor).


Advice please?

[Werner]

Hello, [your first name could be written here],


The tired turning of the starter motor has nothing to do with the fact that it only gets 6 volts.

You already have a start relay; check whether the collector is clean in the insulator joints and has a smooth surface and the brush carbons slide smoothly.

You have to have at least a finger-thick cable from the battery to ground and to the start relay and the starter motor.



Tired starting speed is not a problem, as long as the mixture and spark are correct, the low compression engine comes on at the first revolution.


I connected an on-board charging socket to the battery and screwed it into the heel side of the footwell. That's plug & load.


Gruesse vom Aachener Land!

[springerpete]

I agree with Werner. 6 v Model A Ford's are legendary. Do you have the correct cables ? Are connections clean with no paint ? Starter switch the same ? Are all cells up to a good level ?
I do not deal with the battery in my '29 during the season except hal; way thru when I check the fluid. Bill

[petew]

My 30 is 12 volt and I love it .
It is said that a properly maintained 6 volt system with the correct cables will offer excellent service and I believe that .
For me I just prefer 12 volts .
As for battery location I believe the stock location is fine . I have a battery maintainer on mine and the harness is hard wired onto the battery clamps with the plug hanging under the floor where I can quickly access it to plug and unplug.
Look at the Noco Genius 1 or 2 for a good maintainer , availible on Amazon for us in the USA .
They come with the pig tail wiring that you can hard wire to the battery.

That charger is 6 and 12 volt

[Bob Bidonde]

Speaking from experience, the starter motor does not need any rework to run reliably on 12V. Also the ring gear can handle the higher torque of the starter motor without any excessive wear or breaking loose of the flywheel. The stock Bendix drive however will not survive, so replace it with a modern starter drive that is made in the USA.

[nkaminar]

Sponsored Links (Register now to hide all advertisements)

The horn can be rewired for 12 volts fairly easily. Instructions are here on the barn somewhere.

[Tom Endy]

The Model A works just fine on 6-bolts. However, there are some good arguments for changing to 12-volts. Twelve-volt batteries are not readily available at most auto parts stores. There may come a day when they are no longer available. Modern gadgets need 12-volts for recharging, cell phones and the like.

During the conversion it is best to re-wire the ahooguh horn as the dropping resisters will burn out with repeated use. The attached article is how to do it.

http://www.santaanitaas.org/wp-conte...orn-to-12v.pdf

Tom Endy

[Y-Blockhead]

Originally Posted by Tom Endy

The Model A works just fine on 6-bolts. However, there are some good arguments for changing to 12-volts. Twelve-volt batteries are not readily available at most auto parts stores. There may come a day when they are no longer available. Modern gadgets need 12-volts for recharging, cell phones and the like.

During the conversion it is best to re-wire the ahooguh horn as the dropping resisters will burn out with repeated use. The attached article is how to do it.

http://www.santaanitaas.org/wp-conte...orn-to-12v.pdf

Tom Endy

They're not??

I have had good luck getting 6 volt batteries at the local O'Reilly's. But like Tom suggests, "There may come a day when they are no longer available."

[jrelliott]

Send me an email [email protected] as have a lot of information about bulbs, electrical etc.. I have a 12V negative ground system using the original generator and replaced the 6V battery with a 12V battery. The battery is the load that sets the voltage. You can use a dropping resistor for the horn. I also installed a relay for the horn. Have the Bendix mentioned above on the starter. Have converted the tail lights to LED as they are brighter. Use the 50/32 candle power headlights. There are LED headlights, but do very little driving at night so have not converted.

[Gene F]

Hmmmm. You guys make it sound as if changeover is not all that big of a deal after all. Just follow the process.

So what is the benefit of 12V in the real world?

Can change starter bendix and reuse starter, can rewire horn and resuse, can reuse generator....hmmm.

[gdmn852]

Hello, 6 volt systems work good with proper large size battery cables. I have seen it done a couple of times, people change the battery cables by going to auto parts store and buy “battery cables “ that are for 12 volt systems and are of a much smaller diameter (gauge) than 6 volt and the problems begin.Large cables and good grounds are important. I can understand though if you are running cell phones , cb radios , etc . Converting to 12 volt.

[rotorwrench]

No offense to anyone but I like my antiques to be, well, antique. I love the sound of a good 6-volt starter. I also love the simplicity of the old timey stuff. 12-volts is OK for a model T but they have a magneto and the coils like higher voltage when operating on battery.

[Bruce of MN]

Make sure your battery ground and starter cables are 50 or 55 mm2 size per https://www.lapptannehill.com/resour...nversion-chart

[Gene F]

When I was younger I always tried to buy the 6V cables for my 12V daily drivers because they were heavier. Now days it's all about cheaper, cheaper, cheaper.

[Synchro909]

I have converted all of my four Model As to 12 volts and I've learned a lot in the process and in the 20 years or more since I did the first one. Here are a couple of things about going to 12 volts.
1. The starter will eventually give up unless it is converted to operate on 12 volts. A bent shaft is common a certainty in the long run. Once the conversion is done, the original style Bendix is fine.
2, The is no need for a dropping resistor for the horn. It is a simple task similar to converting the starter motor to convert it to 12 volts
3. There is no need to change the ammeter - it will operate just as well on 12 volts as it did on 6.
4. Your 6 volt coil will be fine if you connect a ballast resistor in series with it. You may be able to get one from an old car or from an electronics supply shop. You will need a resistor of about 1.5 ohms with a minimum of power rating of 40 watts, preferably 50.
Instructions on how to do the conversion to the horn are here somewhere on the forum. If I can find them in my "library" of Model A stuff, I could send you a scanned copy if you like and I could give a detailed explanation of the starter conversion. I have not seen instructions on how to do the starter anywhere but I worked it out from a set of vendor supplied field coils (which failed). I have done several starters for other people and none have failed as far as I know.
Send me a PM if I can help.

[31a]

I have a 12V in my touring mode A because 6V can be hard to find sometimes, my other model As are 6V. The other As have a cut out in the floor board large enough to lift the batter out without removing the floor board. I put the battery maintainer on the starter and the other on a head bolt never had a problem and i have had Model As almost 40 years.


A

[Herb Concord Ca]

All the above about 6 volts is true. A Model A will run just fine on 6 volts just fine. The only reason to change to 12 volts is if you add Air Conditioning to your Model A! Our touring car, 31 Slant Town Sedan has been Air Conditioning since 2010. Converted both the horn and starter to 12 Volts.

[Bruce of MN]

I have the connector leads for my 6V battery maintainer pulled from the battery to near the starter, so it is easy to lift the left hood and plug in the maintainer.

[Big hammer]

Back in 1971 we had a snow storm and it turned very cold, below zero. Well dad said let’s go out and start the family car, it wouldn’t hardly turn over. Well let’s start the pickup, same thing it wouldn’t hardly turn over if even did. Well dad said try your A ( 6 volt ) , pulled the choke and it turned over 2 times very slowly. Waited a few minutes and tried again, it fired and run with the choke about halfway. Dad said take me to the store so he could get new batteries for the modern’s. Oh I had to drive in low gear for about a block because I had the black 600w steam clylinder oil in the transmission and rear end !

[Charlie Stephens]

You don't need to change the ammeter because you are going to 12 volts, you DO need to do something because with your upgraded system you are probably pumping more than 20 amps through the ammeter. I have never found an ammeter that will fit in the original location, all of the replacements are too deep. I solved the problem on my '32 by adding a shunt on the back of the ammeter to carry half of the load. Of course I now have to remember that the ammeter is only reading half of the current. I think you can add a shunt at the terminal box on a Model A but I haven't studied it yet as I am happy with 6 volts.

Charlie Stephens