Page 620 of 705
619 Practical hints
Replacing SmartKey batteries
Replacing SmartKey batteries
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/SmartKey with
KEYLESS-GO*
Replacement batteries: Lithium, type
CR 2025 or equivalent.
Remove the mechanical key out of the
SmartKey or the SmartKey with
KEYLESS-GO* (
page 614).
1Mechanical key
2Battery compartment
Insert mechanical key 1 into opening.
Press mechanical key 1 in direction of
arrow.
The battery compartment is unlatched.
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.
i
When inserting the batteries, make sure
they are clean and free of lint.
i
When changing batteries, always replace
both batteries.
The required replacement batteries are available
at any authorized Mercedes-Benz Center.
Page 637 of 705
636 Practical hintsBatteries
Starter battery (example illustration from
S550)1Negative terminal
2Positive terminal
Disconnecting starter battery
Do not rub the battery with rags or cloths.
The battery could explode if touched due to
electrostatic charge or due to spark forma-
tion.!
Switch off the engine and switch off the ve-
hicle’s internal electrical functions (
page 637)
before you disconnect or remove the battery’s
terminal clamps. You could otherwise destroy
electronic assemblies such as the generator.
Have the battery checked regularly by an autho-
rized Mercedes-Benz Center. Refer to Mainte-
nance Booklet for maintenance intervals or
contact an authorized Mercedes-Benz Center for
further information.
!
Do not connect any consumers directly to
the starter battery. The starter battery will other-
wise be discharged.
i
Only replace a discharged battery with a bat-
tery recommended by Mercedes-Benz. The con-
sumer battery is installed in the trunk in such a
way that it is safeguarded as much as possible
against mechanical destruction in the event of
an accident.
i
Remove SmartKey from starter switch (vehi-
cles with KEYLESS-GO*: Make sure the vehicle’s
on-board electronics have status 0)
(
page 315) when you turn off the engine and
no longer require any electrical consumers. The
vehicle then uses very little power and the con-
sumer battery is spared.
i
If the consumer battery is discharged, you
must use the mechanical key to unlock the vehi-
cle (page 614). Since the vehicle has a sepa-
rate starter battery, however, you can still start
the vehicle.
!
Always disconnect the starter battery in the
order described below. You could otherwise
damage the vehicle’s electronics.
!
Switch off the vehicle’s internal electrical
functions before disconnecting the starter bat-
tery. If the vehicle is stationary for more than one
hour with the SmartKey removed, you do not
need to switch off the vehicle’s internal electrical
functions.
Page 638 of 705
637 Practical hints
Batteries
Switching off vehicle’s internal electri-
cal functions
Shift the automatic transmission toP.
Turn off all electrical consumers.
Turn SmartKey in starter switch to po-
sition 0.
Turn SmartKey in starter switch to po-
sition 1.
Wait for 30 seconds.
The vehicle’s internal electrical func-
tions are switched off.
Turn SmartKey in starter switch to po-
sition 0.Disconnecting starter battery
Open the hood (
page 492).
Use a 10-mm open-end wrench to dis-
connect the battery negative lead.
Remove cover2 (
page 636) from
the positive terminal.
Disconnect the battery positive lead.
Removing starter battery
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).
Fold bar on starter battery up.
Take out the starter battery.
Charging battery
i
Vehicles with KEYLESS-GO: remove the
KEYLESS-GO button (
page 316) and use the
SmartKey with KEYLESS-GO like a normal
SmartKey.
!
Do not remove the SmartKey!
i
For your convenience, have the starter bat-
tery removed by a Mercedes-Benz Center.
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 bat-
tery in its installed position. Contact an au-
thorized Mercedes-Benz Center for
information and availability. Charge battery
in accordance with the separate instruc-
tions for the accessory battery charger.i
Have the batteries charged by a
Mercedes-Benz Center. If you charge the batter-
ies yourself, follow the operating instructions for
your charging device.
Page 639 of 705
638 Practical hintsBatteriesStarter battery
Connect the switched-off charging de-
vice to the terminals of the starter bat-
tery. Observe the operating
instructions in the manual for the
charging device while doing so.
Reinstalling starter battery
Install starter battery in engine com-
partment.
Swing retaining bar down.
Reconnecting starter battery
Make sure that the consumer battery in
the trunk is correctly installed and con-
nected.
Turn SmartKey in starter switch to po-
sition 0 and remove.
Connect the positive lead and fasten its
cover2 (
page 636).
Connect negative lead1
(page 636).
Attach ventilation tube.
Switch on the ignition (
page 315).
Start the engine (
page 359).
Check vehicle functions.
!
Only use charging devices with a maximum
charging voltage of 14.8 V.
Warning!
G
During the charge procedure, there is a risk
of acid burns due to gases escaping from
the battery. Do not bend over the battery
during the charge procedure.
!
The battery and the battery ventilation hose
must always be securely installed when the vehi-
cle is in operation.
!
Always connect the starter battery in the or-
der described below. Otherwise, the vehicle’s
electronics could be damaged.
Warning!
G
Do not drive without a properly installed and
connected consumer battery.
Have any work on the consumer battery car-
ried out by an authorized Mercedes-Benz
Center.
!
Never invert the terminal connections.
!
Make sure that the battery has a plug where
the ventilation tube is attached to it.
Page 641 of 705
640 Practical hintsJump startingJump starting should only be performed on
the starter battery. The starter battery is
located in the engine compartment on the
passenger side (
page 634).
Make sure the two vehicles do not
touch.
Secure vehicle in place with electric
parking brake.
Shift the automatic transmission toP.
Turn off all electrical consumers, ex-
cept hazard warning flashers or work
lights.
Open the hood (
page 492).
Start the engine of the vehicle with the
charged battery and run at idle speed.1Positive terminal of your vehicle’s
battery
2Positive terminal of other vehicle’s
battery
3Negative terminal of other vehicle’s
battery
4Negative clamp
Warning!
G
Keep flames or sparks away from battery.
Do not smoke.
Observe all safety instructions and precau-
tions when handling automotive batteries
(page 634).
i
Vehicles with KEYLESS-GO: remove the
KEYLESS-GO button (
page 316) and use the
SmartKey with KEYLESS-GO like a normal
SmartKey.
Page 642 of 705
641 Practical hints
Jump starting
Remove red cover from positive
terminal 1.
Connect positive terminal2 of the
charged battery with positive
terminal1 of the discharged battery
with the jumper cable. Clamp cable to
charged battery2 first.
Connect negative terminal3 of
charged battery to jumper cables and
attach other end4 to a suitable
ground point on the vehicle.
Get into vehicle and start engine within
30 seconds.
If the starting attempt does not suc-
ceed:
Turn the SmartKey in starter switch
to position 0.
Take out the SmartKey.
Turn off engine of donor vehicle, re-
start it and let it run at idle speed
for several minutes.
Disconnect the jumper cable during
this time.
Reconnect jumper cable as de-
scribed before.
Restart engine.
While the engine is running, switch off
several electrical consumers such as
the blower.
Disconnect jumper cables first from
ground point4 and negative
terminal3, then from positive
terminals1 and2.
Have the battery checked at the near-
est authorized Mercedes-Benz Center.
!
Never invert the terminal connections.
