Dead Battery

I own a 2005 Cavalier and have had it in the shop 4 times in the past two months, because the battery keeps going dead. They have run power tests and are saying everything is reading normal, but cannot figure out the problem. I was wondering if any of you might know a solution to what might be causing the battery to keep going dead.

check out the proceedure I posted in this thread:
http://www.chevroletforum.com/m_11221/tm.htm