CAUTIONFor technical reasons, on vehicles with the description “AGM”, the electrolyte
level cannot be checked.
Note
The battery acid level is also checked regularly by a specialist garage as part of
the inspection service.
Charging
Read and observe
and on page 194 first.
A properly charged vehicle battery is essential for reliably starting the engine.
›
Switch off the ignition and all of the electrical components.
›
Disconnect both battery cables (“negative” first, then “positive”) only when“rapid charging” the battery.
›
Attach the terminal clamps of the charger to the battery terminals (red =
“positive”, black = “negative”).
›
Plug the mains cable of the charger into the power socket and switch the
charger on.
›
Once charging is complete: Switch off the charger and remove the mains ca-
ble from the power socket.
›
Only then disconnect the charger's terminal clamps.
›
Reconnect the cables to the battery (first “positive”, then “negative”).
It is not necessary to disconnect the battery cables if you are recharging the
vehicle battery using low amperages (for example from a mini-charger). Refer
to the charger manufacturer's instructions .
A charging current of 0.1 multiple of the total vehicle battery capacity (or low-
er) must be used until full charging is achieved.
Both cables must be disconnected before charging the battery with high
amperages, known as “ rapid charging”.
The vent plugs of the vehicle battery should not be opened for charging.
WARNING“Quick-charging” the vehicle battery is dangerous and requires a special
charger and specialist knowledge.CAUTIONOn vehicles with the START/STOP system, the pole terminal of the charger
must not be connected directly to the negative terminal of the vehicle battery,
but only to the engine earth » page 212, Jump-starting in vehicles with the
START STOP system .
Note
We therefore recommend that vehicle batteries be rapid charged by a special-
ist garage.
Replacing
Read and observe
and on page 194 first.
The new vehicle battery must have the same capacity, voltage, current and
size as the original battery. Suitable vehicle battery types can be purchased
from a specialist garage.
We recommend having the battery replaced by a specialist garage, where the
new vehicle battery will be installed properly and the original battery will be
disposed of in accordance with national regulations.
Disconnecting or reconnecting
Read and observe
and on page 194 first.
The following functions are initially deactivated or are no longer able to oper-
ate faultlessly after the vehicle battery has been disconnected and reconnec-
ted.
FunctionOperating measureElectrical power window (operational faults)» page 64Panoramic sliding roof (operational faults)» page 218Enter the radio/navigation system code
number» User manual of the radio
or » user manual of the naviga-
tion systemSetting the clock» page 32Data in the multifunction display are de-
leted.» page 44 196General Maintenance
›Start the engine of the vehicle with the discharged battery.›If the engine does not start, halt the attempt to start the engine after 10 sec-
onds and wait for 30 seconds before repeating the process.›
Remove the jumper cables exactly in the reverse sequence as for clamping.
Both batteries must have a rated voltage of 12 V. The capacity (Ah) of the bat-
tery supplying the power must not be significantly less than the capacity of
the discharged battery in your vehicle.
Jump-start cables
Only use jump-start cables which have an adequately large cross-section and
insulated terminal clamps. Obey the instructions of the jump-start cable manu-
facturer.
Positive cable - colour coding in the majority of cases is red.
Negative cable - colour coding in the majority of cases is black.
WARNING■
Do not clamp the jump-start cable to the negative terminal of the dis-
charged battery. There is the risk of detonating gas seeping out the battery
being ignited by the strong spark which results from the engine being star-
ted.■
The non-insulated parts of the terminal clamps must never touch each
other – there is a risk of short circuit.
■
The jump-start cable connected to the positive terminal of the battery
must not come into contact with electrically conducting parts of the vehicle
– there is a risk of short circuit.
■
Route the jump-start cables so that they cannot be caught by any rotat-
ing parts in the engine compartment.
■
There must not be any contact between the two vehicles otherwise cur-
rent may flow as soon as the negative terminals are connected.
Jump-starting in vehicles with the START STOP systemFig. 185
Engine earth: START STOP sys-
tem
Read and observe on page 211 first.
The jump-start cable must only be connected to the engine earthing point on vehicles with the START STOP system » Fig. 185.
Jump-starting vehicles with the vehicle battery in the boot
Fig. 186
Detail of the engine compart-
ment: Jump-starting point
Read and observe on page 211 first.
On vehicles with the vehicle battery in the boot, the positive terminal of the
battery supplying the power can only be connected to the jump-starting point
in the engine compartment of the vehicle being started by means of a jump-
start cable » Fig. 186.
›
Open the protective cap of the jump-starting point in the direction of the ar-
row » Fig. 186 .
›
Connect the positive terminal of the battery supplying the power with the
jump-starting point.
›
Attach the negative terminal of the battery supplying the power to a solid
metal part firmly connected to the engine block or to the engine block itself.
›
Start the engine.
212Do-it-yourself
