dead battery this morning

[Gordy_Schesel at allianzlife.com]

My wife used the Avant yesterday, but then left the headlights on.  Not
noticing this, they were on overnight.  It was in the driveway, so all I
had to do was put the charger on it for a few minutes.  I have also left
the lights on a time or two, when the warning alarm has not been working.
Lately it has not been working.  It is an intermittent thing, and I assume
it is caused by a bad electrical wire (?) in the wiring harness to the
driver's side door.  Both of my Audis have this intermittent electrical
problem, and I think the time is right to get it fixed once and for all.
Or, at some point,  I will end up regretting not getting it taken care of.

Any other lister have experience with this problem and was able to locate
and implement a fix?  Any advice or tips are greatly appreciated.

TIA
gordy in st paul

91 200 20v tqa, pearl, 106k miles
91 100 10v quattro sedan, bamboo, 196k miles