alternator vs. battery

[brock]

Hey guys! If you remember I got a 2001 996 turbo black/red GT 2 look in January. All has been great until today! (34,000 miles). I had the car checked out for an oil leak at the local dealer 2 weeks ago and he dismantled the AC etc. to take a peak. I told you this so you see why Im asking a question below!

Anyways, today right after I washed the car I pulled out and while going thru the gears easy I got a "warning, generator-battery" light. My voltage was around 11 on the cars needle.

I got home and checked the battery level which was 30%. I recharged the battery to 100% but the voltage was still around 11.5 or so.

Is this an alternator failure or could the tech forgotten to hook something back up? I havent driven the car much since I had him look at it. Is this a problem with these cars? Seems like 34k is a little soon to have an alternator prob??

Is there a quick tip on determining if it is the alternator without a diagnostic computer? Share your thoughts and thanks!

Brock