Charging starter and system batteries via jump start terminal point
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2011 BMW 328xi, 2011 BMW 328i, 2010 BMW 328xi, 2010 BMW 328i, and 2009 BMW 328xi. However, it is still accessible from the selected car via links, so may be relevant.
The starter battery is charged as a matter of priority with a charger connected to the jump start terminal. The voltage at the starter battery is the decisive factor in determining whether the system battery is also included in the charging operation. The auxiliary control unit automatically detects a charging operation at a charging voltage at the starter battery of = 13.5 V. The cut-off relay is closed and thus the system battery is connected in parallel. Both batteries are now charged.