You can connect accessories with a maximum power consumption of 180 W to the permanent power supply.
You must not charge a trailer battery using the power supply.
The trailer socket of your vehicle is equipped at the factory with a permanent power supply.
The permanent power supply is supplied via trailer socket pin 9.
A qualified specialist workshop can provide more information about installing the trailer electrics.
Useful information
This Operator's Manual describes all
models and all standard and optional
equipment of your vehicle available at the
time of publication of the Operator's
Manual. Country-specific differences ...
Dashboard
...
Notes on technical data
The data stated here specifically refers to
a vehicle with standard equipment. Consult
an authorized Mercedes-Benz Center for
the data for all vehicle variants and trim
levels. ...