Generator

John, you can diagnose whether the generator is defective by *temporarily* attaching a jumper from the "F" (field) stud on the generator to a good grounding point on the engine or airframe.

If you don't have a voltmeter on your instrument panel, you need either (a) one that either plugs into the cigarette lighter outlet, or (b) a handheld voltmeter/multimeter attached somewhere on the bus or battery to show the voltage in real time.

When the "F" stud is grounded, you're forcing the generator into full output. (The voltage regulator normally controls this) so when you start the engine with the "F" stud grounded, if you raise the RPM too much you will have an overvoltage event!

The test procedure is... remove fuses or pull breakers on all radios, transponders, and other avionics. You only need the starter, battery, ammeter, and voltmeter for this. Now, start the engine and keep watching the voltage. As you increase RPMs, the voltage will rise unless the generator is defective. The ammeter will also swing to the positive "charging" indication. Don't throttle up past 14.5 volts!

If the generator is good, then you either have a bad regulator or a broken wire. The wiring is pretty simple, so you should be able to trace it all out. It's not unusual to find frayed wires or corroded end connectors, so don't trust a wire you haven't fully examined even if a voltmeter finds continuity.

IMPORTANT NOTE: The master switch in the Ercoupe is handling a lot of amps every time you use the starter... more amps than that switch was designed for. It's a 2-pole switch so it's possible that the pole carrying the "F" field voltage has failed, even though the other pole is allowing the starter to energize. Be suspicious of this switch! The Alpha Aviation STC that removes the high-amp load from this switch is a great investment.   

 

Thanks for responding. We tried , but still we are not getting what we are looking for. It may be a bad generator, so it may be time to look into an alternator..
Thanks Again, John

Thank you for responding. We tried but so far no real progress. It may be time to consider an alternator.

Thanks again John

It doesn't even need to be running to do the flash. I use a piece of wire to jump power from the +  post on the starter to the A stud on the generator. Master on (for power at the starter post) but engine is not running. Just a quick touch of the wire to get a spark and then it was good to go. Aircraft had been in storage for years.

Later, I switched to the new solid-state regulator that can auto-flash the armature so it's been no worry since then.

 

While the engine is running, put a jumper between the armature connection on the voltage regulator (middle pring) and momentarily "flash" it to the positive side of the battery. There is no need to disconnect any wires or connect any wires besides the jumper. After the initial flash at the battery post, it doesn't spark anymore. After the initial spark, bring the rpm up to at least 1500 and the amp meter should come to life.
It took so much time to figure this out, I literally typed these instructions and put it in my aircraft logs.
I hope it works, if so you will know right away. Please let me know if you're successful

David, If you can tell me how to Flash the field I will give it a try. I really appreciate the help.
John