Battery draining fast

my Car wouldn't start the other day. thinking it was the alternator I pulled that out, had it checked at Autozone... came back good... took my battery in and it was bad. replaced it but after driving to work and back the next day I couldn't get it to start again. jumped it but it stalled out when I turned the head lights on. took the car to a shop and they couldn't find anything wrong except the battery was dead. they said the alternator was charging the battery but when I picked the car up on a charged battery and drove to work and back it wouldn't start the next day. If the alternator is charging when the car is stationary could driving it be causing the alternator to not work or would it be something else?

Batteries don't always come fully charged. It's good rule of thumb to let your car idle for 30-40 mins. after getting a new battery, to get a good charge started.

yea, thats not the problem however. I drove the car for about 65+ miles and then it died again. the battery was then fully charged when I dropped the car off at the mechanic. got it back and within 2 days it was completely dead again. I just got the battery charged at autozone for free but I don't want to put it back in if its just going to happen again. any other ideas as to why it would be fine while the car is not moving but the battery is suddenly dead when I go to start the car again after driving for 60+ miles or about 1.5-2 hours. feedback and input welcome