Battery drains only when car is running... Help

YY1 said

My 70 Super Bee used to burn out one diode in the alt about every three weeks. I used to keep a box of stators/ bridges and alternator halfs in the trunk. Every now and then you could find me off the side of the road "rebuilding" the alt. I got to where I could tell by the ammeter needle and the brightness of the lights, if it had burned one, and got to where it only took about 15-20 min to disassebble/reassemble. I'd take the bridge back home and swap out the bad diode, then put the rebuilt one back in the trunk for next time.

Changed the regulator several times, but never figured out what was causing it.

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All kidding aside, I've had a couple of alternators "get out of line." What I mean by that is, at high RPM, the case would loosen just enough to allow the stator/ cases to vibrate and wear out of alignment. When it gets bad enough it will do one of two things----

either allow the rotor to rub on the stator

and/ or the vibration will loosen the stator windings and then they will vibrate against winding -- to -- winding and rub the insulation off the windings, which obviously causes internal shorting.

On my 69, when I finally found the source of the problem---one night I had the hood up with the engine running, and it was putting on a min-light show inside the alternator --thunder' n' lighnin' 'n everything