Well if it makes you feel better I have done the same thing lol... one time I had a problem where my car had a hard time starting, like it barely had enough juice to turn the engine enough to start it. I had Autozone test my charging system (with everything connected, enging running type of test). They said the test showed everything was fine, no problem with the battery, alternator, etc. So I wasted some time checking other things, trying to figure out if maybe the starter was going bad or something, then my Dad says "hey this is Arizona, batteries go bad quickly, take the damn thing out and have it tested!" Once they tested the battery OUT of the car it showed as being bad and I bought a new one, end of story lol...