Ml500 (W163) 2003

Question by JakeSaraki posted 6 months 2 weeks ago in M-Class

It seems that my battery drains, but not always, I tested the battery and alternator, everything seems to be in order.
Original car battery is in the car.
It does not matter how cold it is outside, one degrees Celsius or 15.
Some were I saw that people were talking about some module for the electric seat?
The rear windshield wiper or heat do not work.