This is a follow up to this question that I asked previously.
Since asking that question, I have kept my same commute, but have been driving consistently 30+ miles on the weekend. In addition, I have brought my car to the dealership where they re-confirmed that the battery system was fine. In the meantime, I've been checking the voltage daily with a multimeter. The results are, consistently, as follows:
Morning: 12.1 V
At Work: 12.7 V
Evening: 12.1 V
At Home: 12.7 V
In addition, the voltage with the engine turned on is consistently 14.4 V or higher. This means that both overnight (~14 hours) and while I'm at work (~10 hours), the voltage is dropping from 12.7 (fully charged) to 12.1 (barely charged). My conjecture is that there is some parasitic draw which is draining the battery over an extended period of time, but I do not have the equipment necessary to test it myself.
I asked the technician at the dealership is this voltage drop was acceptable and he gave me a "sometimes that happens" answer. Is this voltage drop acceptable, and is there a diagnosis other than a parasitic draw that I can test myself or ask a mechanic to look into?