I want to buy a bmw 530i it has battery problems is it normal

2 questions you need to ask yourself BEFORE buying this car , how clean/well maintained was this car , and how deep are your pockects. NO telling what electrical issues it has , without testing/confirming issues .Electrical can be very 'funny'. IF it's a nice car and it is worth it to YOU (nobody else) , than go for it , fix whatever , and ENJOY the ride!!!Good luck.