BMW F10 battery discharge message
What does the Battery discharge message on the F10 mean?
The message appears when the battery discharges faster than normal, often because of the cold. The car may switch off electrical consumers such as the seat heater and the blower, and they return when the charge rises. An old or weak battery causes the same message most easily.
How do I find out whether the quiescent current is too high?
Measure the current with a clamp meter when the car is locked and has gone to sleep. Under 80 mA is fine. Right after locking the current can be higher for a moment, but it should drop close to zero. Things that prevent sleep are a device left in the OBD port, the tailgate switch and the battery monitoring.
Does the battery need replacing, and does the new battery need coding?
A weak battery causes vague fault codes in electrified cars, so testing the battery and replacing it if necessary is a good first step. The new battery is registered to the car with a diagnostic tool, and if the battery type or size changes, it is coded to the car. After the replacement it is worth clearing the fault codes.
Is a battery voltage of 13.7 V a fault?
Not necessarily. A full battery at rest is about 12.7–12.9 V. A higher reading means the battery has just been charged.