AudiForums.com - Please help stuck on parking lot time ticking!!car wont start

Hello everyone
This morning I came across a very strange problem on my
A6 2001 Quatro 2.8 Base model
after a long trip to Detroit from Chicago over memorial weekend the car did not give me any problems, I even manage to move the car to a parking spot closer to my house, Chicago street parking sucks
This morning I went to turn the car on and it simple just will make an intermitent click click click noise and It would not start, the guy behind me was leaving and I asked him for a jump, the car started after a little charge, once I reach my destination about 15 to 20 mins later a pay parking lot downtown I turned the car off and tried starting it again and nothing, a that point I was running late for work, so I left the car in the parking lot, now can some one help me out to troubleshoot this? the alternator was changed less than a year ago, also I left a usb charging hub connected on the cigarrete ligther in the back witch I disconnected , donyou guys thing that the battery got drained? also how long do I have to drive the car to charge the battery again if 15 to 20 min wasnt enough? , any help would be apreaciated !!