Battery capacity in BMW
The main screen shows 2 capacity figures xxx / yyy mAh. This respectively represent the remaining and total capacity of the battery measured in milli-Amp/hour.
The total capacity is either retrieved from the phone when available or manually entered in the settings, defaults to 1200.
If the value retrieved from the phone looks wrong or the default 1200 is not suitable, you can override the value in the monitoring settings. This can happen when using extended batteries which are not well supported by Android kernel.
Please note that mA and mAh data are not provided by Android OS, but by the underlying kernel, which is often customized by the manufacturers themselves. Some manufacturers decided to simply remove those data and others to keep them but in different places!