If you have a volt meter or multimeter, measure your battery voltage when the engine is off. It should be above 12V. I had a similar issue when I didn't use my F10 for more than a month, battery voltage was 11.7V. The battery drain was so much that even when I resumed driving it for a few weeks, the battery voltage remained around 12V. Eventually I had to recharge the battery with an external charger. Now the battery voltage with the engine turned off is 12.7V (car in deep sleep mode) and 12.4V (engine just turned off and with my camera running).