This was a once in a (long) lifetime event, but I know it's possible to have a battery start your bike just fine and then fail while you're riding it, to the point where the bike just quits running. This happened to me some years back on my ST1100, leaving my wife and I stranded in downtown Seattle. I figured since I was riding along it had to be the alternator. But no, Everett Sports replaced the battery and all was well ever after.