Battery Issue

[cuban_bmwx5]

hey guys
so i have a issue with my X5 for some reason i have to boost it pretty much all the time i boost it on saturday then sunday i start it up fine then monday dead..
i got a new battery installed from bmw dealer and they did a test on the alternator they said it was fine so this issue got me stumped.. now what i want to know is a friend on mine has a e39 and he said he had the same issue some one told him it was the blower regulator he fixed it and now its fine. could that be my issue as well? just wanted to see if anyone else has dealt with this same issue.
thanks hope some one can help me out
(oh and the blower regulator is number 2 on the pic)