Had the same thing on the 182 about ten years ago. Drove me nuts for about a
week until I noticed that the throttle control was adjacent to the diode plate
on the rear of the alternator. Spreading the two apart, you could clearly see
where the throttle cable insulation was chafed through and touching the diode
plate, killing the alternator. Of course, on the ground with the engine torque
not moving the alternator just that few thousandths of an inch that made
contact, it wouldn't do it for love nor money except when the airplane was
actually flying.

Run your hand all the way around the rear diode plate on the alternator and see
if there is a cable nearby.

Jim


Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com