I know this is an older thread but i wanted to inform you of why this happened. You can have weak cells in a battery that test fine under no load. Then when they get under load (starting the engine) they fall flat on their face and cant turn the motor over. As I was reading through this i knew exactly what your problem was. Testing a battery with a multi meter will not give you a true test of the batteries health. You need to test it with a load tester (its basically an 12v electric heater wire that runs the battery power through it to heat the wire and put a load on it) otherwise you will never really know.