Drained Battery

[dafeoh]

Hi ,
MY 2001 4.4i sport X5 decided to die on me..

It cranked yesterday but did not start at first turn of key, but started up fine on second attempt. Drove it about all day and this morning the battery was drained.

It had a similar issue with the old owner and BMW found the E39/45 HEATER FAN RESISTOR came on intermitently and drained the battery - this was in october 2007.

I am tempted to buy a replacement battery before getting a huge bill from BMW , can anyone advise?

or do i just bite the bullet and call BMW?..................