General Maintenance & Repairs - Is my alternator bad?

Today I started up my car and drive about 5 miles up the road. Stopped to get gas, went to turn my car back on and it just click. The lights on the dash were very dim.

Called my buddy over, tried one of those battery pack starters, nothing. Tried jumping it, just clicked.

Pulled the battery out, took to autozone and they did a test, said the battery was bad.

I put a different battery in and it fired right up and I drove home. I am kind of scared to drive it now, not knowing if the alternator is bad. The battery that was in it is only 2 years old ( duralast gold ). I have been told those batteries suck.

While I was driving home the battery amp gauge seemed to be fine.

I am hoping the only problem was the battery took a shit and not my alternator, just can't figure out how it went bad after a 5 mile drive, fired up just fine when I left.

I've had batterys do this also , I wouldn't sweat it much.

my jeep grand cherokee a few years ago had the battery die. wife drove it to work and parked it. came out that night and vehicle completely dead and had to replace the battery in the parking lot. with the engine running if your volt guage on the dash is 13 or above your alternator is working.