After charging my battery to full via charger, I again got the "Battery discharging while stopped" warning. Brought the car to service who checked electrical system and recharged the battery. Two days later I get ""Battery heavily discharged" warning. Brought it back in and this time they changed the battery. It's been one week now and everything still normal. I sure hope things stay that way.
2011 550iX GT, 2011 MB C300 sport, 2003 Porsche C2 Cab (turbo conversion)