Help with battery/alternator/starter diagnosis

[Tickle]

About a month ago, my battery died on me after gradually wearing down. It died at a gas station and I started it by popping the clutch. It ran fine with a completely dead battery(per the gadget that was hooked up to it) for 15-20 minutes. This tells me that my alternator was fine based on it running and idling fine for that amount of time.

Fast forward to today and the car barely turns over, just weak and not enough power to start it. I checked the battery and it read 11.5V. My experience tells me that this is a bad battery.

I haven't had any past experience with parasitic draw, so I'm kind of baffled here. Possible problems:

1.Bad Battery?Maybe I just got a bad one from Sams?
2.Bad starter?
3.Bad Alternator?
4.Parasitic draw?

What do you think? Any advice is appreciated.

I'm going to start by having the battery checked out before I do anything else.

 

[ImThatGuy]

I have had a problem that drained my battery and it took me forever to figure it out. Turns out my ignition chime was staying on that says there are keys in the ignition. I inserted my key and just jiggled it til the chime stopped. Don't know if this helps but it fixed my parasitic draw.