12 volt conversion

[dsarge390]

Hello, everyone.

I'm doing the 12 volt conversion over the winter season. Anyone have a preferred vendor to purchase a complete kit from? I'm not interested in fabricating brackets, or piecing several pieces together to save a buck. Thank you in advance.
P.S., no need to convince me to stay with the 6volt system....

[Beater]

what do you need to make brakets for? buy the alternator kit from one of the venders that sells them, the one wire GM style ones, and bolt it on change out your light bulbs, and coil

[dsarge390]

Has anyone used the kit from Vintage Auto Garage? It looks a little more "original" With cloth wiring and a faux generator, etc...

https://www.vintageautogarage.com/19...t-p/fp2831.htm

[Y-Blockhead]

Originally Posted by dsarge390

Has anyone used the kit from Vintage Auto Garage? It looks a little more "original" With cloth wiring and a faux generator, etc...

https://www.vintageautogarage.com/19...t-p/fp2831.htm

I haven't used a kit but the one in your link appears to use the Powermaster PowerGEN, which I do have and is a nice unit. It looks a lot better than the GM one wire also. The GM just doesn't "look right" on a Model A.
If you don't want to chase down the rest of the parts for the 12v conversion individually, then IMO the kit should fill your needs.

[dsarge390]

Yes, Beater. Most kits do come with the brackets. Some people make brackets out of spring shackles themselves to save $$. Then buy their own alternator, etc. I'm just not interested in that. That's all I was saying.

[Charlie Stephens]

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Remember you can use the original amp meter by running a shunt to carry some of the current.

Charlie Stephens

[BillLee/Chandler, TX]

Originally Posted by Charlie Stephens

Remember you can use the original amp meter by running a shunt to carry some of the current.

Charlie Stephens

???


I don't understand.


An ampere of current is an ampere of current irregardless of the voltage. The stock amp meter works just fine with a 12v conversion. True, the 20 amp swing is low and switching to a 30 amp meter is often done, but "a shunt to carry some of the current"???? No.

[Charlie Stephens]

Originally Posted by BillLee/Chandler, TX

???


I don't understand.


An ampere of current is an ampere of current irregardless of the voltage. The stock amp meter works just fine with a 12v conversion. True, the 20 amp swing is low and switching to a 30 amp meter is often done, but "a shunt to carry some of the current"???? No.

Bill,

I agree that an amp is an amp regardless of the voltage but that is not the problem. The Model A generator is probably good for slightly less than 20 amps but the proposed alternator puts out 90 amps. I realize that this amperage will not be reached except under unusual conditions. If the fan belt is tight enough to put out 90 amps the water pump bearing will probably soon fail. I do think however that the proposed alternator will be putting out far more than 20 amps on a regular basis. The shunt is an extra wire to carry some the current around the amp meter instead of running all of the current through it. I think that putting far more than the rated amperage through the amp meter on a regular basis would shorten its life but I don’t know this for certain. Original amp meters are hard to find and I haven’t heard good things about the reproductions. The 30-amp unit would be better but it is a current reproduction. I am not sure about its quality and if it is even large enough. I am attaching a picture of the back of the amp meter on my ’32. In this case I have a short coil of wire that approximates the resistance of the amp meter. The result of this additional wire is that the reading will be approximately half of the total current. There is a lot of room behind the dash in a ’32. If I was working with a Model A I think I would run two parallel wires from the alternator to the amp meter, each wire heavy enough to carry all of the load in case of an amp meter failure. I would then connect one wire to each side of the amp meter and and remember that the reading was low by a factor of 2. If the amp meter were still pegging on a regular basis I would fine-tune the system by changing the gauge of the wire that carries the current that goes through the amp meter.

Another concern I have is the original wire on a Model A heavy enough to carry the 90 amps? It might be a good question for the company manufacturing the unit. I would get an answer to this before I went too far. Other questions might be what do they recommend for an amp meter and can they throttle down the maximum output of their unit?

Final thought, why would someone need that many amps in a Model A? I wonder if dsarge390 planning to run electric heaters?

Charlie Stephens

[Penthode]

Originally Posted by Charlie Stephens

Bill,

I agree that an amp is an amp regardless of the voltage but that is not the problem. The Model A generator is probably good for slightly less than 20 amps but the proposed alternator puts out 90 amps. I realize that this amperage will not be reached except under unusual conditions. If the fan belt is tight enough to put out 90 amps the water pump bearing will probably soon fail. I do think however that the proposed alternator will be putting out far more than 20 amps on a regular basis. The shunt is an extra wire to carry some the current around the amp meter instead of running all of the current through it. I think that putting far more than the rated amperage through the amp meter on a regular basis would shorten its life but I don’t know this for certain. Original amp meters are hard to find and I haven’t heard good things about the reproductions. The 30-amp unit would be better but it is a current reproduction. I am not sure about its quality and if it is even large enough. I am attaching a picture of the back of the amp meter on my ’32. In this case I have a short coil of wire that approximates the resistance of the amp meter. The result of this additional wire is that the reading will be approximately half of the total current. There is a lot of room behind the dash in a ’32. If I was working with a Model A I think I would run two parallel wires from the alternator to the amp meter, each wire heavy enough to carry all of the load in case of an amp meter failure. I would then connect one wire to each side of the amp meter and and remember that the reading was low by a factor of 2. If the amp meter were still pegging on a regular basis I would fine-tune the system by changing the gauge of the wire that carries the current that goes through the amp meter.

Another concern I have is the original wire on a Model A heavy enough to carry the 90 amps? It might be a good question for the company manufacturing the unit. I would get an answer to this before I went too far. Other questions might be what do they recommend for an amp meter and can they throttle down the maximum output of their unit?

Final thought, why would someone need that many amps in a Model A? I wonder if dsarge390 planning to run electric heaters?

Charlie Stephens

This is crazy. The battery charge current should be limited to no more than 10 amperes. At 12 volts, the current usage is one half for the same power. If double wattage headlamps are used, then the headlamp current at 12 volts will be the same as 6 volts.

You will never see 90 amperes through any of the wiring apart from the starter circuit which is heavy gauge wire. 90 amperes will never go through the ammeter: if you attempted to do so, the wiring will likely burn up before the meter!

[Charlie Stephens]

Originally Posted by Penthode

This is crazy. The battery charge current should be limited to no more than 10 amperes. At 12 volts, the current usage is one half for the same power. If double wattage headlamps are used, then the headlamp current at 12 volts will be the same as 6 volts.

You will never see 90 amperes through any of the wiring apart from the starter circuit which is heavy gauge wire. 90 amperes will never go through the ammeter: if you attempted to do so, the wiring will likely burn up before the meter!

You should go back and read the whole thread. The poster is upgrading to 12 volts and an alternator. If the battery is low (maybe he left the lights on when he went to dinner?) when he starts it the alternator will charge at a high rate. Will it be the 90 amps the alternator is rated for? No for several reasons but I m sure it will still be way above 20 amps and this is one scenario where the amp meter needs protection.

Charlie Stephens

[Beater]

Originally Posted by Penthode

This is crazy. The battery charge current should be limited to no more than 10 amperes. At 12 volts, the current usage is one half for the same power. If double wattage headlamps are used, then the headlamp current at 12 volts will be the same as 6 volts.

You will never see 90 amperes through any of the wiring apart from the starter circuit which is heavy gauge wire. 90 amperes will never go through the ammeter: if you attempted to do so, the wiring will likely burn up before the meter!

my speedster has an delco alt update and 12v system. after start up I see the needle over to 30 plus amp for a bit untll the battery catches up ive never added a shunt, might not be a bad idea

[Mike V. Florida]

Originally Posted by Charlie Stephens

I do think however that the proposed alternator will be putting out far more than 20 amps on a regular basis.
Charlie Stephens

What makes you say that?

For the same resistance, the higher the voltage the lower the current.

What would be used on the vehicle that would draw more than the car on 6 volts?

I just looked this up, the most common alternator used for the Model A, the 6 Volt Delco Remy type 10Si series positive ground alternator with self exciting (one-wire) internal voltage regulator can supply 53 amps. Does everyone who uses a 6 volt alternator change out or modify the ammeter?

[Charlie Stephens]

Originally Posted by Mike V. Florida

What makes you say that?

For the same resistance, the higher the voltage the lower the current.

What would be used on the vehicle that would draw more than the car on 6 volts?

I just looked this up, the most common alternator used for the Model A, the 6 Volt Delco Remy type 10Si series positive ground alternator with self exciting (one-wire) internal voltage regulator can supply 53 amps. Does everyone who uses a 6 volt alternator change out or modify the ammeter?

What makes you say that? I say that because in the case when the battery is low (like someone left the lights on) the alternator (or a regulated generator) will put out more current to rapidly charge it.

For the same resistance, the higher the voltage the lower the current. This statement when taken by itself is wrong. I think what you were trying to say is that a system with higher voltage (12) will require less current than one with a lower voltage (6) to do the same amount of work (burn the lights/honk the horn). Please accept my apology if I am trying to put the wrong words in your mouth.

What would be used on the vehicle that would draw more than the car on 6 volts?
You are absolutely right but the draw is not the issue. The issue is that the output of an alternator (or newer generator) will exceed the output of the original generator.

Does everyone who uses a 6 volt alternator change out or modify the ammeter? I am sure that they don't. What I don't know is how long the amp meters will last when stressed by more current than they were designed to be used with. I admit I don't know but I also don't want to find out the hard way. If you have any data from amp meter life versus current tests I would sure like to see it. Otherwise I would rather err on the side of caution, good original amp meters are hard to find.

Charlie Stephens

[Charlie Stephens]

Duplicate post in error - I sure miss that delete button

[Penthode]

Originally Posted by BillLee/Chandler, TX

???


I don't understand.


An ampere of current is an ampere of current irregardless of the voltage. The stock amp meter works just fine with a 12v conversion. True, the 20 amp swing is low and switching to a 30 amp meter is often done, but "a shunt to carry some of the current"???? No.

I do not understand either. At 12 volts, the current will be one half for the same power dissipation. The current will be less at 12 volts so the same ammeter will be fine.

[Beater]

well when I did mine I bought the kit from snyders I think. GM delco alternator. brakets all there new pulley ect ect. I changed nothing in the wireing, simply hooked up the wire that used to go to the gen to the alternator. been workin fine


rdit I bought the newrex kit all good so far

[MAG]

Don't forget to convert the starter too. I know you will hear ...."I've been running mine for x number of years"...... But that engaging force of 12 volts on 6 volt coils can and will push the starter ring gear off the flywheel.

[BillLee/Chandler, TX]

Originally Posted by MAG

Don't forget to convert the starter too........ But that engaging force of 12 volts on 6 volt coils can and will push the starter ring gear off the flywheel.

And the sky is falling......

[Chuck Sea/Tac]

Originally Posted by BillLee/Chandler, TX

And the sky is falling......

No it’s not, however your ring gear is coming off!

[redmodelt]

If you go with an alternator. They have a smaller pulley so they spin faster at lower speeds, you will also need a clog type belt to fit the smaller diameter pulley. The stock belt is too stiff.