pathy is randomly not starting. brand new optima red top battery. alternator tested good when I tested it last weekend. it's happened twice now. last saturday I drove it all day long, got home, and went to go out 2 hours later and it was stone dead. jumped it and it was fine all week long. this morning when I went to leave for work, it was dead again. I drove it saturday, but not sunday. wtf? possible short somewhere? how does one diagnose something like this?