Dead battery problem

Hello everyone,

I have a 93 lumina apv van with 104,000 miles. The van has been great, but here lately i have had a weird problem. I Replaced the battery in may of 2003. About a week ago the van was dead, so we gave it a jump. It ran fine all day never hesitating to start. Next day it was dead again, so I replace the battery under warranty thinking the battery is bad. It starts all day again but the next morning it was dead again. Jump it once again and check to make sure no lights are being left on, but I cant find anything that might be drawing power. Any ideas?

Have you checked the alternator?

no i havent checked the alternator, but I think I found what might be causing the problem. The tensioner pulley isnt keeping enough tension on the belt and my guess would be that could cause insufficient charging, thus leading to the dead battery every morning. Any thoughts?
Thanks for the reply's

I'd have the alternator checked first. GM's alternators are notorious for going bad...especially on 60* and 90* v6 motors.