One problem related to battery has been reported for the 2003 BMW 530. The most recently reported issues are listed below.
Car has needed to be jumpstarted at least 6 times this year. I've taken it to my local dealer sonnen BMW and they said they would not replace battery because they were able to get it to take a charge. I've recently found a recall (opening campaign #610504) on the control module which I just reported to the dealer. BMW refuses to replace the battery unless the car is so dead it can't be jump started and needs to be towed.