2004 MERCEDES-BENZ SL55AMG battery

324 Practical hintsWhere will I find ...?Vehicles with spare wheel
1Spare wheel
2Electric air pump
3Vehicle tool kit
4Battery for electrical consumers5Jack (under spare wheel)
6Wheel wrench (under spare wheel)Vehicles with TIREFIT kit
1TIREFIT kit
2Electric air pump
3Vehicle tool kit
4Battery for electrical consumers
5Wheel wrench
6Jack

328 Practical hintsLocking/unlocking in an emergency
Using the hex-socket wrench provided
in the vehicle tool kit, carefully turn the
locking screw 2 approximately one
quarter turn.

Hook luggage cover into holders
(page 185).

Let go of the hardtop.
It should gradually lower into the trunk.

When top is completely lowered, return
locking screw 2 to its original posi-
tion.

Close the lid.

Replace the trunk floor.

Visit an authorized Mercedes-Benz
Center as soon as possible.Replacing batteries in the SmartKey/
SmartKey with KEYLESS-GO*
If the batteries in the SmartKey or the
SmartKey with KEYLESS-GO* are dis-
charged, 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.SmartKey
1Mechanical key
2Battery compartment
Replacement batteries: Lithium, type
CR 2025 or equivalent.
!Do not overtighten the screw.
Warning!
G
Keep the batteries out of reach of children.
If a battery is swallowed, seek medical help
immediately.
iWhen replacing batteries, always re-
place both batteries. The required re-
placement batteries are available at
any Mercedes-Benz Center.


329 Practical hints
Locking/unlocking in an emergency

Remove mechanical key (
page 325).

Insert the mechanical key1in side
opening and push gray slide.
The battery compartment is unlatched.

Pull battery compartment2out of the
SmartKey housing in direction of ar-
row.

Remove the batteries.
3Battery
4Contact spring

Using a lint-free cloth, insert new bat-
teries under the contact spring with the
plus (+) side facing up.

Return battery compartment into hous-
ing until it locks into place.SmartKey with KEYLESS-GO*
1Battery
2Tilt battery up
3Mechanical key
Replacement batteries: Lithium, type
CR 2025 or equivalent.
iThe required replacement batteries are
available at any Mercedes-Benz
Center.


330 Practical hintsLocking/unlocking in an emergency
Remove mechanical key (
page 325).

Insert the mechanical key in side open-
ing and push gray slide.
The battery compartment is unlatched.

Pull the battery compartment out of the
SmartKey housing.

Using mechanical key3, apply pres-
sure to position 2.
Battery 1 tilts up slightly.

Pull battery 1 out in direction of ar-
row.

Using a lint-free cloth, insert new bat-
teries under the contact spring with the
plus (+) side facing up.

Return battery compartment into hous-
ing until it locks into place.


358 Practical hintsBatteries
BatteriesYour vehicle is equipped with two
batteries:

The starter battery (located in the en-
gine compartment)


The battery for electrical consumers
(located in the trunk)
Starter battery in the engine compartment1Positive terminal
2Negative terminal
Warning!
G
Failure to follow these instructions can re-
sult in severe injury or death.
Never lean over batteries while connecting,
you might get 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 explosive. Keep
flames or sparks away from battery, avoid
improper connection of jumper cables,
smoking, etc.
!Never loosen or detach battery termi-
nal clamps while the engine is running
or the SmartKey is in the starter switch.
Otherwise the alternator and other
electronic components could be se-
verely damaged.
Have the starter battery checked regu-
larly by an authorized Mercedes-Benz
Center.
Refer to Service Booklet for mainte-
nance intervals or contact an autho-
rized Mercedes-Benz Center for further
information.

359 Practical hints
Batteries
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 acci-
dent.
Warning!
G
The brake system requires electrical power
to operate.
A malfunction in the vehicle’s power supply
or electrical system may impair brake sys-
tem operation and switch it into its emer-
gency operation mode. The same applies if
battery is disconnected. To brake, the driver
must then apply significantly greater brake
pedal pressure and depress the pedal much
further to obtain the expected braking ef-
fect. If necessary, apply full pressure to the
brake pedal. Brakes are only applied to the
front wheels. Stopping distance is in-
creased! Adjust your driving style according-
ly. For more information, see “SBC brake
system” (
page 81).
Warning!
G
With a disconnected battery

you will no longer be able to turn the
SmartKey in the starter switch and
pressing the KEYLESS-GO* start/stop
button on the gear selector lever will
have no effect


the gear selector lever will remain
locked in positionP

360 Practical hintsBatteriesDisconnecting the batteries Disconnecting the battery for electrical
consumers

Unhook the luggage cover in the trunk.

Remove the trunk floor.
The battery for electrical consumers is
located in the right hand area of the
trunk (
page 323).

Use the 10 mm open-end wrench from
the vehicle tool kit to disconnect the
battery negative lead.

Remove the cover from the positive ter-
minal.

Disconnect the battery positive lead.Disconnecting the starter battery

Use the 10 mm open-end wrench from
the vehicle tool kit to disconnect the
battery negative lead.

Remove the cover from the positive ter-
minal.

Disconnect the battery positive lead.
!To avoid damage to electrical compo-
nents, always disconnect the battery
for electrical consumers (in trunk) first.
This applies even if you only wish to
charge the starter battery. Otherwise
the electronics of the vehicle can be
damaged.

361 Practical hints
Batteries
Removing the batteries
Removing the battery for electrical con-
sumers
Remove the screws securing the bat-
tery in the trunk.

Remove the battery support and brack-
et. Take out the battery.
Removing the starter battery

Remove the screws securing the start-
er battery in the engine compartment.

Lift the retaining bracket and remove
the battery.
Charging and reinstalling batteries
Charge batteries in accordance with
the instructions of the battery charger
manufacturer.

Reinstall the charged battery. Follow
the previously described steps in re-
verse order.
Reconnecting the batteries
Reconnecting the starter battery
Turn off all electrical consumers.

Connect the positive lead and fasten its
cover.

Connect the negative lead.
Warning!
G
Never charge a battery while still installed in
the vehicle. Gases may escape during charg-
ing and cause explosions that may result in
paint damage, corrosion or personal injury.
!To avoid damage to electrical compo-
nents, always reconnect the starter
battery (in engine compartment) first. !Never invert the terminal connections!!The battery, its filler caps, and the vent
tube must always be securely installed
when the vehicle is in operation.