Would an improperly installed serpentine belt or a/c belt ruin the alternator? I got a new serpentine belt and a/c belt installed and two days later the suburban wouldn't start, battery dead, too. The service station, the same one that replaced the belts, told me neither of the two belts had anything to do with the alternator going bad, which then drained the battery and killed it resulting in the need for a new alternator and new battery.