Mercedes-Benz C-class Operator's Manual page 326

Therefore, we strongly recommend that you have the
battery charge checked frequently, and corrected if
necessary, especially if you use the vehicle less than
approximately 200 miles (300 km) per month,
mostly for short distance trips, or if it is not used for
long periods of time.
Only charge a battery with a battery charger after the
battery has been disconnected from the vehicle's
electrical circuit.
Always disconnect the battery negative lead first and
connect last.
When removing and connecting the battery, always
make sure that all electrical consumers are off and the
electronic key is in starter switch position 0. The
battery, its filler caps, the vent tube and the opposite
plug must always be securely installed when the vehicle
is in operation.
While the engine is running the battery terminal clamps
must not be loosened or detached, otherwise the
generator and other electronic components would be
damaged.
Battery
Instruments
Operation
and controls
Instrument
Driving
cluster display
Removal of filter box:
Release three clamps (1) and remove filter box.
Installation of filter box:
Install filter box properly and secure with
three clamps (1).
317
Practical hints Car care
Technical
Index
data