Golf IV R32 :: Alternator Malfunction - Battery Is Not Staying Charged

Short version is that my battery is not staying charged. I drive the car daily and am not having any serious issues except for having to put a charger on overnight about once a month or so since this past winter. The current battery (Optima red top) has never gone dead and has been more reliable than the original, it just cranks progressively slower each time I start the car until the day comes that I decide to put the charger on again.

All the lights flicker and dim when driving at night, and have been like that for a few years. When it began, I had the charging system checked three separate times. Once at the dealership who told me everything was fine, once at an Advance Auto who said all was well except for there being an above normal load on the battery with the engine/all accessories off , and once at an alternator/electric motor specialist who said all was well except that the alternator was not capable of generating enough to keep the battery charged long term. They said if I ever got stuck in traffic and sat at idle with the ac/stereo on for an extended period that I shouldn't shut it off since I may not have enough power to crank it again . At first I thought they were going to suggest that I have them repair/rebuild/upgrade it somehow, but they really had no interest in doing so.