12v battery draining in deep sleep

When the car is powered off for an extended period of time, the 12 battery drains. Sometimes to the point the car cannot start anymore. The BMS should check the 12V battery from time to time in deep sleep to recharge it from the big battery if necessary(or recharge the 12v battery on a fixed timer, like every night at 1:00 am). If 12v battery is drained a lot, the user should be notified via infotainment and/or mobile app.