2008 MERCEDES-BENZ SLK55AMG battery

398 Practical hints
Replacing SmartKey batteries
If the batteries in the SmartKey are
discharged, the vehicle can no longer be
locked or unlocked. It is recommended
to have the batteries replaced at an autho-
rized Mercedes-Benz Center.Batteries contain materials that can harm
the environment if disposed of improperly.
Recycling of batteries is the preferred
method of disposal. Many states require
sellers of batteries to accept old batteries
for recycling.
Replacement batteries: Lithium, type
CR 2025 or equivalent.
Remove the mechanical key from the
SmartKey (
page 394).1Mechanical key
2Battery compartment
Insert mechanical key1 into opening.
Press mechanical key1 in direction of
arrow.
Battery compartment2 is unlatched.
Pull battery compartment2 out of the
housing.
Warning!G
Batteries contain poisonous and corrosive
substances. Therefore keep the batteries
out of reach of children.
If a battery is swallowed, seek medical help
immediately.
Warning!G
SmartKey batteries contain Perchlorate
material, which may require special handling
and regard for the environment. Check with
your local government’s disposal guidelines.
California residents, see
http://www.dtsc.ca.gov/HazardousWaste
/Perchlorate/index.cfm.
iWhen inserting the batteries, make sure
they are clean and free of lint.
iWhen replacing batteries, always replace
both batteries.
The required replacement batteries are available
at any Mercedes-Benz Center.

399 Practical hints
Replacing SmartKey batteries
3Batteries
4Contact springs
Pull out batteries 3.
Using a lint-free cloth, insert new
batteries3 under contact springs4
with the positive terminal (+) side
facing up.
Return battery compartment2
(
page 398) into the housing until it
locks into place.
Slide the mechanical key back into the
SmartKey.
Check the operation of the SmartKey.

422 Practical hints
Battery
The battery is located in the engine com-
partment on the right-hand side below the
water tray (
page 423).
1Battery
2Positive terminal
3Negative terminal
Warning!G
Failure to follow these instructions can re-
sult in severe injury or death.
Observe all safety instructions and precau-
tions when handling automotive batteries
(
page 302).
Never lean over batteries while connecting
them, as you could otherwise be injured.
Battery fluid contains sulfuric acid. Do not
allow this fluid to come into contact with
eyes, skin or clothing. In case it does, imme-
diately flush affected area with water and
seek medical help if necessary.
A battery will also produce hydrogen gas,
which is flammable and explosive. Keep
flames or sparks away from battery, avoid
improper connection of jumper cables,
smoking, etc.
Warning!G
Do not place metal objects on the battery as
this could result in a short circuit.
Use leak-proof batteries only to avoid the
risk of acid burns in the event of an
accident.
!Never loosen or detach battery terminal
clamps while the engine is running or the
SmartKey is in the starter switch. Otherwise the
alternator and other electronic components
could be severely damaged.
Have the battery checked regularly by an
authorized Mercedes-Benz Center.
Refer to Maintenance Booklet for maintenance
intervals or contact an authorized
Mercedes-Benz Center for further information.

423 Practical hints
Battery
Disconnecting the battery
1Water tray
2Lock
Apply the parking brake (page 59).
Make sure the gear selector lever* is
set to positionP (manual transmission
to Neutral).
Turn off all electrical consumers.
Remove the SmartKey from the starter
switch.
Open the hood (page 294).
Turn locks2 one quarter turn.
Remove water tray1.
Read and observe safety instructions
and precautions (
page 302) and
(
page 422).
Use a 10 mm open-end wrench to dis-
connect the negative lead from battery
negative terminal3 (
page 422).
Remove the cover from battery positive
terminal 2 (
page 422).
Use a 10 mm open-end wrench to dis-
connect the positive lead from battery
positive terminal2 (
page 422).
Warning!G
With a disconnected battery

you will no longer be able to turn the
SmartKey in the starter switch

automatic transmission*: the gear se-
lector lever will remain locked in
positionP
!Always disconnect the battery in the order
described below. Otherwise the vehicle’s
electronics can be damaged.

424 Practical hints
Battery
Removing the battery
Remove the screw on the swivel bar.
Remove the swivel bar.
Pull out the battery ventilation hose
from the battery (depending on battery
arrangement in your vehicle model, the
ventilation hose is located either on the
left or right side of the battery).
Take out the battery.
Charging and reinstalling batteryCharge battery in accordance with the
instructions of the battery charger
manufacturer.
Reinstall the charged battery. Follow
the previously described steps in
reverse order.Warning!G
Never charge a battery while still installed in
the vehicle unless the accessory battery
charge unit approved by Mercedes-Benz is
being used. Gases may escape during charg-
ing and cause explosions that may result in
paint damage, corrosion or personal injury.
An accessory battery charge unit specially
adapted for Mercedes-Benz vehicles and
tested and approved by Mercedes-Benz is
available, permitting the charging of the
battery in its installed position. Contact an
authorized Mercedes-Benz Center for infor-
mation and availability. Charge battery in
accordance with the separate instructions
for the accessory battery charger.
!The battery, its filler caps and the ventilation
hose must always be securely installed when the
vehicle is in operation.

425 Practical hints
Battery
Reconnecting the battery
Turn off all electrical consumers.
Connect the battery positive lead2
(
page 422) and fasten its cover.
Connect the battery negative lead3
(
page 422).
Reinsert water tray 1 (page 423).
Push in locks2 (page 423) and turn
one quarter turn.
!Always connect the battery in the order
described below. Otherwise the vehicle’s
electronics can be damaged.
!Never invert the terminal connections!
iThe following procedures must be carried
out following any interruption of battery power
(e.g. due to reconnection):

Set the clock (page 141).

Synchronize the power windows
(
page 239).

426 Practical hints
Jump starting
If the battery is discharged, the engine can
be started with jumper cables and the bat-
tery of another vehicle. Observe the follow-
ing:

Jump starting should only be performed
when the engine and catalytic convert-
er are cold.

Do not start the engine if the battery is
frozen. Let the battery thaw out first.

Only jump start from batteries with the
same voltage rating (12 V). Jump start-
ing with a higher voltage battery could
damage the vehicle’s electrical system,
which will not be covered by the
Mercedes-Benz Limited Warranty.

Only use jumper cables with sufficient
cross-section and insulated terminal
clamps.

Always make sure the jumper cables
are not on or near pulleys, fans, or
other parts that move when an engine
is started or running.
Warning!G
Failure to follow these directions will cause
damage to the electronic components, and
can lead to a battery explosion and severe
injury or death.
Never lean over batteries while connecting
or jump starting, as you could otherwise be
injured.
Battery fluid contains sulfuric acid. Do not
allow this fluid to come in contact with eyes,
skin or clothing. In case it does, immediately
flush affected area with water, and seek
medical help if necessary.
A battery will also produce hydrogen gas,
which is flammable and very explosive. Keep
flames or sparks away from battery, avoid
improper connection of jumper cables,
smoking, etc.
Attempting to jump start a frozen battery
can result in it exploding, causing personal
injury.
Read all instructions before proceeding.
!Vehicles with automatic transmission*:
Do not tow-start vehicle.
!Avoid repeated and lengthy starting
attempts.
Do not attempt to start the engine using a
battery quick charge unit.
If the engine does not run after several
unsuccessful starting attempts, have it checked
at the nearest authorized Mercedes-Benz
Center.
Excessive unburned fuel generated by repeated
failed starting attempts may damage the
catalytic converter and may present a fire risk.
Make sure the jumper cables do not have loose
or missing insulation.
Make sure the cable clamps do not touch any
other metal part while the other end is still at-
tached to a battery.

427 Practical hints
Jump starting
Make sure the two vehicles do not
touch.
Turn off all electrical consumers.
Apply the parking brake (page 59).
Make sure the gear selector lever* is
set to positionP (manual transmission
to Neutral).
Open the hood (page 294).
Flip up cover from positive under hood
terminal2 in front of water tray1
(
page 423).1Positive terminal of charged battery
2Positive terminal
3Negative terminal of charged battery
4Negative terminal
Connect positive terminal1 of the
charged battery with positive
under-hood terminal2 in front of the
water tray with one jumper cable.
Clamp the cable to positive terminal1
of the charged battery first.
Start the engine of the vehicle with the
charged battery and run at idle speed.
Connect negative terminal3 of the
charged battery with negative
under-hood terminal4 with the
second jumper cable. Clamp the cable
to negative terminal3 of the charged
battery first.
Start the engine of the disabled
vehicle.
You can now turn on the electrical
consumers. Do not switch on the
headlamps under any circumstances.
Remove the jumper cables first from
negative terminals3 and4 and then
from positive terminals2 and1.
You can now switch on the headlamps.
Have the battery checked at the
nearest authorized Mercedes-Benz
Center.
Warning!G
Keep flames or sparks away from battery.
Do not smoke.
Observe all safety instructions and precau-
tions when handling automotive batteries
(
page 302).
!Never invert the terminal connections.