Generator Questions

Thanks for the help. I'm going to try and wire it up over the weekend. I bought a solid state negative ground cutout from Snyder's and a new ammeter just to rule the old ones I had out. This is my current wiring diagram and how I plan on wiring it. The only thing that is sill 6 volt is my electric fuel pump and starter, everything else is 12 volt. Can you check my wiring diagram out and let me know if everything looks correct or not? I will check the generator out again and make sure everything is like you're saying. Thanks.

CurrentWiring.jpg
 
The 12V negative ground model T semi conductor is just a cutout with a diode. That means no points to stick but you won't have voltage regulation. This type cutout will give a constant charge at whatever amprage that the third brush is set for. If the charge rate is set over five or six amps the continuous charge will boil the battery. You can easily smoke the semi conductor cutout if you try polarizing the generator with it in place or if it is wired incorrectly. If you plan on head lights you would have to constantly adjust the third brush because if you ran with enough amps for headlamps, when the lights were turned off the amprage would be too high and would soon cause all kinds of problems.

I'm not sure that the way you have it wired will work. I did cover the way that my cars are wired in the second paragraph of my first post on this thread. If you don't have a brattons catalog or the original style repro wiring harnesses, here is what I would do. run the positive battery cable to the post on the starter switch, yellow wire from starter switch to the right post of the terminal box. When I say which side this means if you were sttting at the drivers seat. Connect a yellow wire to the right side of the terminal box to the right post of the ammeter, yellow wire with black tracer from left terminal of the terminal box to the left post of the ammeter, run a wire from the distributor to one side of a replacement style ignition switch. Red wire from other side of ignition switch to the minus - side of the coil for negative ground, black wire from plus side of the coil to the left terminal of the terminal box, Yellow wire with black tracer from output post of cutout to the left terminal of the terminal box. you can either hook the fuel pump to the side of the ignition that the red wire connects and ground the other wire from the pump to ground. This would shut down the pump when the ignition was off or you could run a seperate hot wire to a toggle switch and the other side of toggle switch to the pump and you could cut the fuel pump off without cutting off the engine. This should be enough wiring to get it running for tests. I don't know how long the 6V fuel pump will will last on 12v but may not be a problem. You may not even need a fuel pump. I am running dual updraft carbs on two of my model A's on gravity flow. If you can do without the pump, I think you would be better off. The starter will work good on 12V but I recommend useing the barrel starter drive on any model A for reliability.

Now for the tests and possible adjustments. With the repro cutout installed go ahead and polarize the generator as I described in previous posts. Next if the third brush is at the top of its travel you will need to push the third brush assy. down a bit. crank it up and see where the needle on the ammeter is pointing. I would be looking for 5 or 6 amps either way for this test. I would set the throttle for a fast enough idle to bring the generator up to sufficient rate to run the engine. This will be the test to see if the generator is charging and if you will need to reverse the wires on the ammeter. With the engine running at a fast enough idle watch the ammeter needle, it needs to be moving one way or the other for this test. While watching the ammeter needle remove the ground cable from the battery while the engine is running for a very short time and if the engine continues to run the generator is charging and you are running off the generator. If the engine doesn't quit running and the needle is pointing to discharge you will need to reverse the wires on the ammeter. Make this test quick because charging rate will climb with the ground cable off. I have tested this way many times but it needs to be QUICK and NEVER with the fun regulator or the simi conductor cutout in place. Only the repro cut out for this test or you will ruin something FOR SURE. If these tests passed or were adjusted to work and the generator is charging and showing a charge on the ammeter you are ready for the next adjustment. You will now need to adjust the third brush for an 8 and not more than 10 amp charging rate. rev it up and observe the ammeter it doesn't need to go past 10 preferably 8 amps with the engine reved or damage will eventually occur. This will be all the amps that you can expect to get with this set up but with the fun regulator installed you will have voltage regulation like a modern car. I would send the semiconductor cut out back because you will have NO REGULATION with it. Eight amps has worked good for me but if you plan on using the most powerful halogen bulbs you will have problems.

Brattons sells a 60 amp armature but the Fun projects regulator won"t work with the higher amps. Bratton offers NO suggestions for a regulator but the later V8 regulator can be rigged up to handle the job but thats another story, a lot of typing and I haven't tested the set up yet. Later! Good luck and keep me posted.
 
I got back home early this afternoon from work and had some time to try out my new parts and the generator. I took the generator off and put in a new post kit since it needed it and also a new insulated wire that runs to the post since it needed it to. I installed the soild state Snyder's cutout and new ammeter gauge. Only thing in my wiring diagram that is or was wrong is the wires at the ammeter gauge. I had to reverse them.

When I turn the key on now it says -15 discharge with the electric fuel pump running. When I start the motor up it says -15 discharge when its at idle. When I start to give it some gas the ammeter hand goes on over to 0 or very little charge. When I gave it some more gas, I'd say about 1/3 of the gas pedal down the ammeter hand goes on over to about 8 or 9 on the ammeter.

That's all the time I had for testing this afternoon. I will give it a road test tomorrow and post my results. As far as the fuel pump goes I have to run a fuel pump since I'm running a downdraft intake and Stromberg 97 carburetor. This is a Model B motor by the way.

Thanks for all the help so far, will keep you posted.
 
reverse the ammeter wires if it discharges when you give it gas. A quick check would be to turn on the headlights and it will show a charge if the wires are reversed.
 
I just got back from a road trip with it. I got my lights wired back up this morning to. Driving it down the road about 45 to 50 the ammeter shows about 0 to +6. At idle the hand is right below 0 and showing a small discharge, now keep in mind I have an electric fuel pump running at all times. When getting down on the pedal the ammeter hand moves on over to about +9 to +12, but only for a second or two. With my lights on and the fuel pump running a idle I show a discharge of about -9 to -12 at startup, after a minute or two the hand comes on back to just a small discharge, once I give it some gas the hand on the ammeter comes to 0 or a slight charge.

I think all is well. Any thoughts?
 
Sorry for taking over and reviving this old thread.

I have a 1938 Ford Business Coupe that previously ran on a 6V positive-ground system. Over the winter, I converted the system to 12V negative-ground. Everything went well so far, but I’m not getting any charging voltage.

I used the original 6V generator from the 59AB engine and installed NOS 12V field coils from ACE. They connect to the "Field" terminal on one side, run through both coils, and finally ground to the housing.

I didn't touch the "Armature" terminal. When I run the generator as a motor (bridging Field and Armature, connecting ground to battery negative, and touching battery positive to the Field terminal), the generator spins clockwise (viewed from the front).

For the regulator, I’m using an NOS Standard Plus VR-35. Terminal B gets 12.6V from the battery, terminal F goes to the generator's Field terminal, and terminal A goes to the generator's Armature terminal.

Before starting, I applied 12V positive to the generator's Field terminal (with the regulator disconnected). When I start the engine, the voltage drops from 12.6V to 12.4V (likely due to the electronic ignition drawing power); even when I increase the RPM, I don't get a proper charging voltage—instead, it drops slightly further to 12.38V.

As a test, I swapped the wiring harness cables for jumper wires and added an extra ground connection. I also temporarily installed a charge indicator light between the 12V battery and the regulator's A terminal, but it doesn't go out.

Any advice?
 
As far as the comment that the ammeter wires had to be switched because the diagram was wrong, the most likely case is the diagram is correct - it's the ammeter that is wrong. From what I have been told by generator rebuilding experts (Model T and A), ammeters made in the few decades are designed for 12-volt negative grounded electrical systems. So, when the 6-volt positive grounded Model A diagrams are followed, it appears that the wires are incorrectly drawn to the ammeter because the needle goes to the opposite direction than expected. It is necessary to swap wires so that the ammeter's needle goes into the positive side while charging and the negative side when discharging, such as turning on the lights or honking the horn, both of which are electricity hogs.
Marshall
 
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