2004 Kia Sedona MY VAN EATS BATTERIES!

I am on brand new battery # 3! I went out to check it just a minute ago and. Guess what? DEAD! Nothing works, not even the door locks. There is absolutley no juice getting to it; it makes no sound when I try to start it. Just nothing.
had it to the dealer in June because the check engine light was coming on, then going off, and the van was stalling. They said there was no codes showing. It still does that check engine light thing, too. When it runs! JUNK!