Hallo id3_firstmover, den workaround kenne ich nicht, kannst du das noch ein bisschen genauer ausführen, was der macht. Oder wo finde ich etwas darüber? Klingt nützlich.
Ich hab es (u.a.) in der Facebook-Gruppe gelesen. Dort hat ein User ausführliche Messung an der 12-V-Batterie im Ruhezustand vorgenommen und kam dann u.a. zu folgenden Erkenntnissen (ich hoffe, ich darf das hierher kopieren, ggf. ist der ursprüngliche Verfasser Stephan S. ja auch hier aktiv, zumindestens hat er in FB mal nen Link in dieses Forum gesetzt):
(Quelle: Facebook ID.First Movers Club 3. 12.2020, Hervorhebungen in fett von mir)
" +++ 12V Battery measurements update +++
While we have to wait for the “big” update, I want to share my lessons learned on how to avoid problems and workshop visits after having spent more than 2000 very happy kilometers in my 1st Max so far.
I have experienced myself some of the reported issues, starting from Airbag control lamps, not working ACC, disabled BT, disfunctional mode or climate control buttons, and so on. Fortunately, I always could fix such glitches and I never experienced a dead battery. (knocking on wood)
All those problems, including a dead battery are in my observations either caused by:
1. a hardware defect (typically accompanied by ugly red error messages)
2. the bus system is not going into sleep mode
In the rather rare case 1. there is nothing what you can do - you need to contact your workshop. In 2. which I would guess is the 95% case, a reset of the computers followed by a 15 minute quiet phase with the car locked and keys out of reach will usually resolve the problem.
So what causes the bus system not to enter sleep mode? From what I have experienced:
1. pressing the brake pedal or start/stop button frequently without actually driving 2. pressing the drivers seat sensor frequently without driving, eg while cleaning the carpet I frequently leaned on the seat, which caused the system to start/stop in short interruptions- result was the airbag warning light on. 3. Walking frequently in front of the car with the keys in the pocket, eg when you are working in your garage with the car nearby.
All that can result in the well known malfunctions, and when it comes bad, in an uncontrolled battery drain when the system can’t shutdown. In my tests I could reproduce a battery drain up to 8-10 Amps. You can do the maths, a 12V battery even in top condition would be dead after 5 hours. And it’s obvious that a trickle charger connected to the 12V battery is not capable of preventing the disaster in this case.
What can you do to avoid this?
1. give the system ALWAYS time to boot. Like in the old Diesel days when you had to pre-heat the motor for 30sec or so, wait until the infotainment has fully started up before you enter into a drive mode. 2. Avoid frequently pressing the brake pedal or start/stop button before you leave the car 3. Avoid frequently hopping in and out in the drivers seat before you leave the car. 4. Disable active keys - yes a nice function, but when I saw the current draw when you approach the car I immediately disabled it in order to protect the battery.
What can you do when the battery is dead?
- unlock the car with the emergency key - try to jump start with a booster or a jumper cable from another car
- drive a few kilometers and then do a infotainment reset followed by 15 min “sleep” while keeping the hood open - If you have a clamp ampere meter measure the current flow in all black cables connected to the plus pole - Current across all cables must be lower than 100-300mA after 10 minutes of sleep. - if not, or if the battery is dead again, contact workshop - Otherwise connect a good battery charger and load the battery until it’s full again.
The 12V battery will be charged when you sit in the drivers seat, when you drive, and when you have the car connected to your wallbox and charging the HV battery as shown in the diagram below.
