Quick story, my trusty Mercedes had a hard time starting the day after Christmas and was thinking the battery was going bad. The next day it was completely dead.
Bought a new battery and the next day it was completely dead again. Well, I should have known better and done some research or diagnostics first.
Through this video I confirm with my multimeter, by looking at the amp draw with the car off and key not inserted.
This problem is common over multiple platforms and not limited to the W211 E-Class
