I recommend bringing your X5 to the dealer. I've had that message twice...then a few days later a complete battery drain where I couldn't start the car. I had to call Roadside Assistance both times - all they did was boost my X5. After the second incident, I brought my X5 to the dealer and they "claimed" it was due to my daily short distance driving - and so they simply replaced my battery. It's been 2 months and so far so good! (knock on wood).