MTFCA Forum

I see Lang's has a 6v and 12v alternator for the same price. I have no problem keeping my 24 Coupe 6v but is their and pros to going to a 12v alternator? Would it cause problems with the buzz coils? I have a feeling it would.

Coils run fine or even better on 12v.

Your starter my not like it after a while.

Kerry wrote: ↑

Sat Jan 28, 2023 11:52 pm

Coils run fine or even better on 12v.

Doubling the volts make the buzz coils work better?? I would think it would burn them out

Model T Ron wrote: ↑

Sun Jan 29, 2023 12:41 am

Kerry wrote: ↑

Sat Jan 28, 2023 11:52 pm

Coils run fine or even better on 12v.

Doubling the volts make the buzz coils work better?? I would think it would burn them out

It does not, a good mag will put out 30V.

12V is very hard on a 6V starter.

There have been numerous discussion in the past the only positive claim for 12volts was a faster discharge from the coils and how that would effect timing https://www.mtfca.com/discus/messages/5 ... 1464833674
The culprit to destroying coils isn't voltage but rather amperage
The issue with 12volts on the coils isn't the issue, rather it is amperage https://www.mtfca.com/discus/messages/1 ... 1321373211
By Ron Patterson November 15, 2011
The Model T coil is designed to operate at 1.3 amps, anything higher and your simply creating an internal overheating situation. It doesn't make any difference if you use 6 or 12 volts. The coil is slower to operate on 6 volts and a conversion to 12 volts speeds the coil up so it works well at higher engine speed. I wrote an article on this subject several years ago which explains why running the coil on 12 volts when the magneto is inoperative is a good solution. The only thing you have to beware of when operating coils on 12 volts is NOT to let them buzz continually without the engine running.
I saved the PDF pointed to by the broken link in the above article More on Model T Spark Timing --
Here is an article about everything you didn't want to know about alternators https://www.carparts.com/blog/a-short-c ... g-systems/
Almost all alternators include a Voltage Regulator. The article explains that the regulator voltage will cut off at a certain voltage but the amperage generated will depend on the state of the battery.
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The 12volt alternator would harm your starter, its the 12 volt battery that will it will eventually kill
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6 volts alternator / battery combination suits the Model T electrical system (starter, bulb sockets etc).

Crazy thought here...you could retain your original generator

when thoroughly and thoughtfully rebuilt and limited to around 4A, they will last longer than most owners will

and if doing it yourself is too much to take on, a proper rebuild (the "best quality" version) is about the same price and shipping cost as an alternator

Finally, purchasing a properly rebuilt generator (not a $100 Krylon rebuild off of eBay) will keep skilled vendors in business and encourage others to take up the mantle when they retire, rather than simply sending the bucks to China.

It looks to me like alternators have more drawbacks than a stock T generator. If you want to carry 12 volt mobile devices, navigation aids, etc, a small 12 volt battery will power most of them for days of use. For LED lighting, phones, etc, I believe that converters are available to operate 12 volt low current devices off a 6 volt battery. Ideally, a stock T generator would be modified for external field regulation, with maximum current limited to 8 amps or less. If I felt that I needed an alternator, I'd look into a belt-driven setup, with a small, Japanese-type alternator mounted about where accessory water pumps are mounted, or a 6 volt vendor-supplied alternator with a belt pulley. I would not run a 6 volt starter on 12 volts.

If you are going 6 volt I would recommend a T generator. Alternators have a lot of problems and I have witnessed on tours. If you need 12 volts then use an alternator.
Norm

12V is very hard on a 6V starter.
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I would think you could put a thicker 12v cable going to the starter to slow it down a bit.

A smaller gauge cable could reduce the starter's torque a little once the starter was engaged and under load. It would do little or nothing to protect the starter drive and flywheel.

Model T Ron wrote: ↑

Sun Jan 29, 2023 4:36 pm

12V is very hard on a 6V starter.

I would think you could put a thicker 12v cable going to the starter to slow it down a bit.
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Thinner. Use a 12v cable. That doesnt solve the problem. There is the initial engagement slam that does the most damage. A thinner cable or tuoted bendix spring as a resistor doesnt fix the problem.

This is on Lang's webpage for Alternators:

Questions and Answers
Is this starter for 6 Volt or 12 Volt?
This starter is set up for the 6 volt, it can work for the 12 volt it just spins at a higher speed then it should. you can knock the voltage to it by running 12 volt battery cables to it that will slow it down some, making it so it is not so harsh on the bendix

Model T Ron wrote: ↑

Sun Jan 29, 2023 7:09 pm

This is on Lang's webpage for Alternators:

Questions and Answers
Is this starter for 6 Volt or 12 Volt?
This starter is set up for the 6 volt, it can work for the 12 volt it just spins at a higher speed then it should. you can knock the voltage to it by running 12 volt battery cables to it that will slow it down some, making it so it is not so harsh on the bendix

Thats nice, but I stand on what I said.
Wording is incorrect. You cannot knock down the voltage from 12 to 6 with smaller cables. You can lower the amperage available @ the starter. Still the initial engagement will damage the bendix.

God Bless Langs, but that statement is Pure Baloney

No one is right all of the time, and that is a great example of it...

John is absolutely right

If you used a small enough cable, or any other resistor, to operate a Model T 6 volt starter on 12 volts while avoiding abuse of the starter drive and flywheel, the starter motor would not have enough power to effectively crank the engine. Operating a T starter on 12 volts invites shedding flakes of metal into the engine oil and onto the magneto parts, and risks having broken starter drive parts loose in the engine/transmission.

It would be possible to rig up a system whereby a button would activate a solenoid which would apply current to the starter sufficient to engage the starter drive, at which point the driver would have to instantly release the button and step on the starter swtich, which would apply full battery current. This would spare the starter drive and flywheel, but it would cause the starter switch to engage with the starter motor loaded, and you'd still be slamming the starter motor with much higher current than it was designed to handle reliabley.

Would this work if you could afford it

The smaller cable only works to slow down on load. There is a way to rewind the starter for 12 volts. I'm sure someone here knows how to do it, or buy one which has already been done.
Norm

Oh dear, this is going off the rails somewhat...

I may be different for others but for me, in my country, it really is better to use 12V. This is because 6V batteries are very expensive here, 6V bulbs are harder to find (and more expensive) than 12V, 12V LED lamps are easily available, the stock generator will happily charge a 12V battery, coils run better on 12V, reduced current requirements mean old wiring etc is likely better able to cope, and finally it's more probable that 'modern' equipment will run on it.

With regard to the starter; ideally you need to wire the field coils for 12V - or just fit the 12V coils obtainable from various vendors. Another option if you're not keen to do this yourself is to ask people like Ron Paterson or AdminJeff to do it for you (there will be others, sorry for not mentioning you, it's just these are the two people I've seen talk about doing this work). Either way it's not especially difficult or expensive to do it properly.

Changing the supply wiring to the starter can really only do one thing - alter the resistance in the feed circuit. If you make the wire thinner it will have a higher resistance, conversely a thicker wire (or double wires) will be lower the resistance. From there you can use Ohm's law to determine how it will all work, but from the practical perspective of the starter it probably won't significantly change the speed and initial shock of the starter gear hitting the ring gear because when it's spinning in free space it isn't drawing a lot of current.

Once the starter is engaged and turning the motor over a thinner supply wire will get warmer and the higher resistance of thinner wire will ultimately mean lower power from the starter. In all I suggest it's not worth the effort and complexity of messing around with cables etc when it's easy to simply deal with the starter properly and inexpensively. At the same time you could properly overhaul the starter (brushes, lube bearings etc as needed) so it will be ready to give you good service for a long time.

As far as the original question goes; in my view if you're going to the trouble of fitting an alternator I'd change the system to 12V, it will not adversely impact the coil operation.

I'd say more but this subject has been covered many times and it might be easier for those uncertain about these things to have a read of existing threads and perhaps after that come back with any points that require clarification?

Luke.

Two identical 6 volt batteries in series with a full gauge center tap for the 6 volt starter would work well for the starter. I'm not sure an alternator's regulator would be entirely happy with the arrangement, or that the batteries themselves would be. Using the starter would load only one of the batteries, which would leave you with what is effectively a 12 volt battery with 3 partially discharged cells. That could lead to issues with both the alternator regulator and the batteries.

If it ain't broke don't fix it. If You want to keep the car 6 volt. there is a wide selection of 6 volt LED bulbs now available for both headlights and other lights on the model T. Keep the connections clean. make sure battery to starter switch and switch to starter are heavy gauge cable and have not been replaced over the years with light gauge 12 volt cable. The model T will start just fine on 6 volts. It will spin a little slower than twelve volts but a lot faster than You can hand crank it as it was designed to be started in 1907. Good Luck.

Who has the bulbs posted above? Are they a direct replacement?

Smith and Jones has the flat style. Fit just fine except the bulb orientation makes the leds vertical and not horizontal. Not sure about the round one. Try super bright led.com. They might have them!

Smith and Jones has the flat style. Fit just fine except the bulb orientation makes the leds vertical and not horizontal. Not sure about the round one. Try super bright led.com. They might have them!
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Snyder's has correct LED's for a model T but at $49.95 each that seems high

https://www.ledlight.com/searchresult.aspx?KeyWords=6v

Has both types
Just look for the correct base type