Batteries are covered under your warranty, but from defects in material or workmanship.
But for example , They are able to tell if you left the lights on for 2 nights while you were away for instance. If so.. you have kille dthe battery and it wont recover.
you would be amazed at how many people leave lights on, or comfort access keys IN the car, and end up with dead batteries.
That is why you hear both sides of the story... and no one really confesses to leaving the lights on.
of course you could have a draw, or a bad alternator...
'11 128i M-Sport Pkg, Sport Susp., 6AT w/paddles, BMW Perf CAI,Charcoal Filter Delete, BMW Perf. Big Brake Kit, BMW Perf. Exhaust, Ferodo 2500's, Titanium shims,135 trunk lip, BMS-PBX Box-Map 3, Castrol RBF600 ,e93 FSB, , f30 Backing Plates,GC Camber Plates, Hankook RS-3's (Track setup)