2007 MERCEDES-BENZ SLR CLASS battery

357 Practical hints
Replacing SmartKey batteries
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
authorized 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 out of the
SmartKey (
page 355).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.
iWhen inserting the batteries, make sure
they are clean and free of lint.
iWhen replacing batteries, always replace
both batteries. The required replacement batter-
ies are available at any Mercedes-Benz Center.

358 Practical hints
Replacing SmartKey batteries
1Mechanical key
2Unlocking the battery compartment
3Removing the battery compartment
4Slide
Insert mechanical key1in side
opening, push gray slide4 in direction
of arrow2.
The battery compartment is unlatched.
Pull battery compartment out of the
housing in direction of arrow3.5Battery
6Contact spring
Remove the discharged batteries.
Using a lint-free cloth, insert new
batteries5 under the contact
spring6 with the plus (+) side facing
up.
Return battery compartment into
housing until it locks into place.
Slide mechanical key1 back into the
SmartKey.
Check the operation of the SmartKey.

367 Practical hints
Batteries
Batteries
Your vehicle is equipped with two batter-
ies:

The starter battery (located in the
trunk)

The battery for electrical consumers
(located in the trunk)
Warning!G
Failure to follow these instructions can
result in severe injury or death.
Never lean over batteries while connecting,
you might get injured.
Observe all safety instructions and precau-
tions when handling automotive batteries
(
page 256).
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.
!You must not jump start the vehicle, other-
wise the vehicle electrical systems could be
damaged.
Only use the battery charge unit tested and ap-
proved by Mercedes-Benz for use on the SLR to
charge the battery or maintain the battery
charge. Using other battery chargers may cause
damage to the vehicle and/or personal injury.
Information on charging the batteries
(
page 368).
Have the batteries 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.
If it is necessary to replace the batteries, contact
an authorized Mercedes-Benz Center.
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.

368 Practical hints
Batteries
Charging the batteries
You can obtain detailed information on
charging the battery from your authorized
Mercedes-Benz Center.
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
increased! Adjust your driving style
accordingly. For more information, see
“Electro-hydraulic brake system”
(
page 86).
Warning!G
With a disconnected battery

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

the gear selector lever will remain
locked in park positionP
Warning!G
Never charge a battery while still installed in
the vehicle unless the battery charge unit
approved by Mercedes-Benz (supplied with
your vehicle) is being used. Gases may es-
cape during charging and cause explosions
that may result in paint damage, corrosion
or personal injury.
A 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 information and
availability. Charge battery in accordance
with the separate operating instructions for
the battery charger.

369 Practical hints
Batteries
Charging with the battery charger
Only use the battery charge unit approved
by Mercedes-Benz and supplied with your
vehicle. This charger is designed to auto-
matically control the charge rate, and
charge the battery or maintain the existing
charge in the battery while the vehicle is
parked and not being driven for long
periods of time (on average approximately
3 weeks or more). Not driving the vehicle
for such extended periods may cause the
charge in the vehicle battery to drop.
Using the charging point
The charging point for the battery charger
is located next to the CD-changer on the
left-hand side in the trunk.1Charging point
Remove the SmartKey from the starter
switch.
Open the cover of the charging
point1.
Connect the battery charger with the
charging point 1.
Observe and follow the separate
operating instructions for the battery
charger.
Charge up the battery.
The battery charger switches off
automatically when the battery is
sufficiently charged.Using the charging terminals
The charging terminals for the battery
charger are located in the trunk under-
neath the interior floor.
1Negative charging terminal
2Positive charging terminal
Connect positive terminal2 and
negative terminal1 with the battery
charger. Start with the positive
terminal2.
Charge up the battery. Observe and fol-
low the separate operating instructions
for the battery charger.

371 Practical hints
Towing the vehicle
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. 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! Adapt your driving style according-
ly. For more information, see
“Electro-hydraulic brake system”
(
page 86).
With the engine not running, there is no
power assistance for the brake and steering
systems. In this case, it is important to keep
in mind that a considerably higher degree of
effort is necessary to brake and steer the
vehicle. Adapt your driving accordingly.
!Towing of the vehicle should only be done
using the properly installed towing eye bolt.
Never attach tow cable, tow rope or tow rod to
the vehicle chassis, frame or suspension parts.
iTo signal turns while being towed with the
hazard warning flasher in use, turn SmartKey in
starter switch to position2 and activate the
combination switch for the left or right turn
signal in the usual manner – only the selected
turn signal will operate.
Upon canceling the turn signal, the hazard
warning flasher will operate again.
iWhen towing the vehicle with all wheels on
the ground, please note the following:
With the automatic central locking activated and
the SmartKey in starter switch position2 the
vehicle doors lock if the left front wheel as well
as the right rear wheel are turning at vehicle
speeds of approximately 9 mph (15 km/h) or
more.
To prevent the vehicle door locks from locking,
deactivate the automatic central locking
(
page 139) and switch off the tow-away alarm
(
page 94).
iThe gear selector lever will remain locked in
park positionP and the SmartKey will not turn in
the starter switch if the battery is disconnected
or discharged. See notes on the battery
(
page 367).

372 Practical hints
Towing the vehicle
Installing/reinstalling towing eye bolt
Take the towing eye bolt1 from its
storage compartment (
page 353).
1Towing eye bolt
Remove cover from the access hole.
Screw towing eye bolt1 clockwise in
to its stop.
Remove the towing eye bolt when you
no longer need it. To do this, carry out
the above steps in reverse order.
Points to bear in mind

The vehicle must not be tow-started.

If the vehicle is to be towed, only tow it
with all wheels on the ground.

If the vehicle has suffered transmission
damage, only tow it with the propeller
shaft disconnected.

Before towing the vehicle, make sure
the battery is connected and charged.
Otherwise you will not be able to switch
on the ignition and move the selector
lever to neutral positionN. There will
then be no power assistance when
steering and braking.
Transporting the vehicle
The towing eye bolt can be used to pull the
vehicle onto a trailer or transporter for
transporting purposes.
Switch on the ignition (page 40).
Move the selector lever to neutral
positionN.
!Only secure the tow bar to the towing eye
bolt. The vehicle could otherwise be damaged.
!Your vehicle is equipped with a front towing
eye bolt only (
page 372).
You cannot tow other vehicles with your vehicle.
!Due to the low clearance height of the SLR,
care must be taken when loading and unloading
from a transporter to avoid damaging the vehicle
body work.
To secure the vehicle, only tie it down by the
wheels or tires. Otherwise it could be damaged.

386 Technical data
Electrical system
Mercedes-Benz SLR McLarenMercedes-Benz SLR McLaren 722 Edition
Generator (alternator)14 V/150 A14 V/150 A
Starter motor12 V/1.7 kW12 V/1.7 kW
Battery
Starter battery12 V/35 Ah12 V/35 Ah
Battery for electrical consumers12 V/70 Ah12 V/70 Ah
Spark plugsNGK ILFR6ANGK ILFR6A
Electrode gap0.031 in (0.8 mm)0.031 in (0.8 mm)
Tightening torque18 – 22 lb-ft (25 – 30 Nm)18 – 22 lb-ft (25 – 30 Nm)