Charging issue '70 Swinger
....................... never disconnect battery with engine running, this action will kill.......................
X10. I WISH I could put this wives tale to bed. THIS NEVER WAS a legitimate test, and you will never see this "test" taught in any automotive school, or in any textbook, shop, or motors manual, or even Haynes or Chilton, for that matter. The newer the car is, and the more electronic components in the car, the greater chance for a failure.
AND it PROVES NOTHING.
A If the engine happens to be idleing SLOW enough that the system won't charge, you might mistakenly believe you have a problem
B If the alternator has some damage, IE bad stator or diodes, you might have a "10A" alternator instead of a 30, 40, or 60A alternator. So it MIGHT just generate enough juice to operate the engine and you might mistakenly believe you do NOT have a problem
using relays to operate lighting loads, .
THIS IS ONE situation that actually might contribute to a problem with these symptoms. IF YOU USE relays for several things, such as lights, and the ignition/ regulator circuit, AND if you still have the factory ammeter, the AMMETER WILL NO LONGER READ CORRECTLY, and furthermore, when you have the "relay loads" turned on, (might add fans, stereo) this will cause the ammeter to FALSELY read upscale and lead you to believe it is charging when in fact it MIGHT be centered or even dis-charging.