After starting my '26, the amp meter would show no charge. Increasing engine speed would change nothing. Wondering if the cutout was damaged, I quickly touched the pliers handles across the wire attachments on the cutout, and immediately the generator started charging, and the noise from the gears subsided due to the increased load on them.
Wondering if anybody else has had the same symptoms, and what the cause and fix might be.
What you did was flash the generator to start the charging process. I at times have had to do this. The Model T generator needs a certain amount of residual magnetism to start the charging process. If the generator sits to long that magnetism can dissipate.
Another cause maybe resistance caused by a dirty/burned commutator or bad brushes. The solution is to clean up the burned commutator with a honing stone while it is rotating with the engine running. Electrical contact cleaner may be used to clean the grease or oil from the commutator or brushes. I hope this helps.
It does it every time, even after just being shut off for a few minutes. Doesn't loose the residual magnetism that fast, does it?
I have cleaned the commutator surface and the slots, but not the brushes. I was thinking that if the charge output is good once it gets to charge, the brushes should not be the problem, but that may be faulty thinking on my part.
Honing stone? I was taught a popsicle stick wrapped with a small piece of emery paper did the job just fine.
Clean the brushes but it may be too much negative lead on the brush plate. Also, check to make sure the cutout isn't "leaking". With the engine off, there should be 0.0 volts at the generator terminal.
What is happening is that your generator is not able to get itself started by being able to put out a small current large enough to operate the cutout. This small current is generated by the residual magnetism of the generator and I don't agree that it will go away if the generator sits for awhile. What is really likely happening is that dust from the wearing of the carbon brushes is mixing with oil inside the generator which has likely leaked past the front seal and this oil/carbon dust has formed a paste that is simply a resistor that is leaking just about every connection inside the generator to the ground portion of the generator. This resistance is drawing off the small excitation current and not allowing it to build up the output of the generator enough to operate the cutout and get the whole process going. Jumpering the cutout makes the generator start charging because it applies the battery current back into the armature of the generator which gives a boost of current to the field and that gets it started. It will then charge until the output of the generator drops enough so the cutout drops out and then the system is dead again. This is something I have seen on several generators. What you need to do is pull the generator and really get it flushed out to remove all the oily carbon paste out of the generator. Then stop the oil leak into the thing and you will likely find it now works again. Carbon paste is a resistor that provides a current path sufficient to do this. Oddly enough I found this leakage current once in an ignition switch on a friends motorcycle. The owner had used a product called LOCK EASE which was for lubricating key locks. It was a lube that contained graphite as the lube along with a liquid to help it get into the lock mechanism. It lubed the ignition keyswitch just fine but put the same sort of paste into the switch and provided about a 50 mA leakage current that kept running his battery down in no time - same exact problem except in this case it was discharging the battery since this sort of product was for a door key lock and not a key operated ignition switch.