Roadrunner, I know. It is a strange deal. It's a brand new batter and when I test it with my meter (not running) it shows 12.5 volts. Start the tractor, do the same test and it shows 6.5. It's also a brand new alternator (3 wire).What you are saying makes no sense at all. A 12V battery that ever showed as low as 6V would never crank the starter in the first place. I think either you've got a flaky meter, or didn't get it well connected. If not that, I don't know. This is not rocket science. There ARE coils made to run without resistors, you need to go to the source (store?) where you got this coil and find out. Virtually all 12V CARS and LIGHT TRUCKS from the first 12V to present run either a ballast resistor or "resistor wire" in the harness. This means that they are not truely "12V coils" they are "12V with the proper resistor" There are OTHER "general purpose" (industrial and tractor) coils sold that are designed to run directly off 12V.
Can you post a diagram? If nothing else, draw it out, take a photo, and use "tinypic" http://tinypic.com/ to post the diagram.
Ammeter, doesn't the tractor have one? Basically, ONLY the battery connects to one side, everything else, gen/ alternator and all loads, come off the other side
Alternator? single wire (I hate those things) Three wire? How is it wired.
Wrong ground polarity? Take a **** of a good look at the battery and cables. There's only ONE right way to run a 12V system, and that's negative ground. Was the battery every COMPLETELY dead? It IS possible, if someone is a complete "tool" to discharge a battery and then charge it back up the wrong polarity.
Find another meter. Find a friend. Take some more readings, and make SURE This is not rocket science. It's tractor science. I could do this when I was 13 years old. And I did.
Your wiring is wrong... nothing from the alternator should be hooked to your coil. The charging circuit should have one wire form the amp to the battery terminal on the back of the alternator.
On the 12SI the two terminals are usually labeled 1 & 2 with the one cloest to the battery terminal being 2. That is to be wired to the battery terminal. Short jumper, it is voltage sensing for the regulator.
The 1 terminal is the exciter, it should be connected to an idiot lamp going to the ignition switch or is available an accessory terminal on the switch or even a momentary contact switch like a push button. Once the alternator is excited it will charge until you shut the engine off. REMEMBER this MUST be isolated from the ignition or you will NOT be able to shut off your engine.
Roadrunner, I know. It is a strange deal. It's a brand new batter and when I test it with my meter (not running) it shows 12.5 volts. Start the tractor, do the same test and it shows 6.5. It's also a brand new alternator (3 wire).
The tractor does have an amp gauge. I put a new ceramic resistor, 12v coil, points, distributor cap, plugs, wires and rewired it this morning because it was doing the same thing before and I thought it wasnt charging.
Here's how it's wired up:
- one wire from alternator F connection to coil and then wired to one side of the ceramic resistor
- one wire from post on alternator with jumper to R on alternator to the amp gauge
- one wire from other side of amp gauge to starter solenoid.
- ignition to other side of resistor
- ignition to solenoid
- Solenoid to starter
Another weird thing. With the ignition on (engine not running) I can take a reading at the top of the coil and it reads 11 or more volts. Fire up the tractor, and it drops to 6.5 again.
Tested it without the resistor and got the same exact scenario. Makes no sense at all to me.
I am no rooky with mechanicing, but admit that wiring can be a challenge...on something new. Geez, this thing is 69 years old and only has 2 main wires. Should'nt be that tough I know.
Thanks for anything else to try,
Luap
