Model T doesn't charge, why not?

O

oldmotorsguy

Senior Member
I have a 1926 Ford Model T Tudor, and the ammeter never indicates a positive charge. It indicates a negative draw when the lights are turned on, but never a positive.

I put a volt meter on the gen. cut out and grounded it: it reads 6.1 volts. When the engine is running: 6.1 volts. The battery will discharge completely after starting perhaps 20 or 30 times, even though I run it on magneto. A friend diagnosed the generator armature as bad.

I have replaced the generator with a Lang's rebuilt generator. Still no positive charge. I replaced the gen cut out, still zip.

Why is this system not charging? I assume the ammeter is working, since it shows a negative drain when I turn the lights on. Am I wrong here?

Anybody?
 
The Ammeter is in series with the charge wire to the battery. If the ammeter is no good the battery will not charge. Can you get a reading at the two sides of the cutout?
 
Your cut out may not be working properly. It happens often on my car. If I don't see a reading I take jumper wires across both sides of the cut out and touch them several times. It will spark but do that and check the meter it should start working. If it doesn't you have to keep the jump wires on while running. BUT, do not leave on when engine is stopped as the generator will keep running and burn up. Vice versa, I f you do not get the meter to work the generator will fry. I would check this out with a generator guy as I'm an novice and don't want to steer you down the wrong street. Gud luck
 
I am no expert but here goes! How was the armature checked, were the field windings checked on the old generator? What type of cutout do you have? Do you know that the cutout is working? Did you flash the system as stated above? Do you know that the cut out is good?

Try reversing the wires at the amp meter, does it show a positve charge when you turn the lights on, this would show that the amp meter is not stuck, don't forget to put the wires back.
What it sounds like is you are reading the battery voltage on the battery connection of the cutout.

Maybe the battery is fully charged and is telling the cutout that it does not need any more charge. When the battery charge drops the voltage at the cutout is less and the points close sending current to the battery. When the battery voltage reaches its optimum level the points open and the current made is sent to ground and will show zero at the meter.

Remove the cutout and take a reading from the gen output to ground using an analog meter. What is your DC amp reading? Look for 10 amps at a fast idle. If you have that then you know the gen. is putting out.

If the meter check out good, and all connections are good and the cutout is know to be good I would have the battery checked.

If you run the car before fixing, put a jumper from the gen to cutout terminal to ground and disconnect the battery wire and wrap the end of the wire with tape. Do not run with the cutout bypassed. You will be putting full output of the gen into the battery.
 
Have you cleaned the commutator? If you really want to troubleshoot the problem, then use a methodical approach. If you just want to shoot in the dark and hope you get it, then use all of the posts you receive. You will chase your tail and spend a lot of time. It takes less than 30 minutes to actually troubleshoot one of these.
 
If it is a rebuilt unit from Langs I don't think you will need to clean the commutator and the brush should be set.
 
I agree with Doug in that a methodical approch is best.

I would not think the problem is based in the generator or cutout
since you have replaced both with "new" parts.

Check your wiring first to see that something has not been mixed up.

The problem is possibly an open circuit in the wire from the cutout to the switch. This could be intermittent in that you have a 6.1 v reading at the cutout - see that this is consistant at the terminals, not just the wire ends. The terminal block connection can often be corroded as well.

The fact that your lights work indicates that the battery side of the ammeter is connected & the ammeter is passing current to the switch.

The down side is that if the circuit is open from the cutout to the switch it is possible to severely damage the generator if the car is run. This applies to your new generator as well. If an engine is to be run without the generator connected, the output post of the generator should always be grounded to the case.
 

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Ok, how about this, what kind of cutout do you have? If it mechanical it does not matter if it neg or pos. ground. If it is diode or other it does. Did you flash the gen to polorize the current flow?
 
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