I'll be the first to admit that when it comes to cars, I'm not an expert on mechanics. Apparently, people who are paid to be mechanics don't know much about cars either.
My car battery died yesterday morning. It's been coming for awhile; every once in awhile I could feel the car have a tough time turning, but yesterday it was done. I called AAA. The AAA guy comes and can't start the battery. So he says, "It's not the battery, it's the starter." The he says, "Actually, it might be the alternator."
So I sit in the car, watch him do his thing. He checks the alternator and it's apparently fine. He "fixes" the starter. Then he "jumps" the battery. I turn the ignition and the car turns, but barely. There's a Monro shop right around the corner from where I live. I get the car there.
I walk in and tell the guy what's happened to date. "It's the alternator," he says. I drop off the car, walk home and wait for a call. Monro guy calls back and says, "We checked out the alternator and the starter. The only thing that's wrong with the car is you need a new battery."
A new battery has been installed. I can't wait to start my car tomorrow and listen to it stall.