Battery care and maintenance
WARNING: This page is about a different car, the 2013 BMW 550i GT, 2012 BMW 550i GT, 2011 BMW 550i GT, and 2010 BMW 550i GT. However, it is still accessible from the selected car via links, so may be relevant.
In low-maintenance batteries, check the electrolyte level at least once a year. If necessary, top up with distilled water up to the top marking.
The increasing number of electronic control units in the vehicle reduces the self-discharging time of the battery (even in standby mode). To maintain the battery service life and to avoid exhaustive discharging, recharge laid-up vehicles every 6 weeks at the latest.