I had same problem but i added water (was really Low) and didnt drive it around or anything and it died right and left, Mine wouldnt even last though the day.
I put my old charger on it for 3-4 days to build the acid backup and after that it has worked great ever since.
on another note,
My bro had same issue with his old 2001 taurus, he had installed XM Radio himself, and the taurus has a very stupid radio in it (its actually in the trunk.) and we think(never checked) that he mis-wired it a bit. Because EVEN with the xm OFF it would die after 2days but he didnt have to worry about that since he drove it every day.
