Well try the battery calibration. If that doesn't help, an app may help you. I recommend Battery Monitor Widget, and now BMW's functionality is also a part of Android Tuner. It sort of combines Battery Monitor Widget and System Tuner into one app. It can actually tell you the capacity of your battery (in mAh) to help you decide if the battery is sub-standard, or will help you pinpoint the source of battery drain (assuming it is legitimate).