Mercedes-Benz S-Class Saloon W223 2021 Owner's Manual page 384

382 Breakdown assistance
& WARNING Risk of explosion during charg-
ing process and starting assistance
During the charging process and starting
assistance, the battery may release an explo-
sive gas mixture.
Avoid fire, naked flames, creating sparks
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and smoking.
Make sure there is sufficient ventilation.
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Do not lean over a battery.
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& WARNING Risk of explosion from a frozen
battery
A discharged battery may freeze at tempera-
tures slightly above or below freezing point.
During starting assistance or battery charging,
battery gas can be released.
Always allow a battery to thaw before
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charging it or performing starting assis-
tance.
If the indicator/warning lamps in the instrument
cluster do not light up at low temperatures, it is
very likely that the discharged battery has frozen.
In this case you may neither jump-start the vehi-
cle nor charge the battery.
The service life of a battery that has been thawed
may be dramatically shortened. The starting char-
acteristics may be impaired, especially at low
temperatures.
It is recommended that you have a thawed battery
checked at a qualified specialist workshop.
Plug-in hybrid: be sure to observe the notes in the
Supplement. You could otherwise fail to recognise
dangers.
All vehicles
* NOTE Damage caused by numerous or
extended attempts to start the engine
Numerous or extended attempts to start the
engine may damage the catalytic converter
due to non-combusted fuel.
Avoid numerous and extended attempts
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to start the engine.
P223 0288 02
Observe the following points during starting assis-
tance and when charging the battery:
Only use undamaged jump lead/charging
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cables with a sufficient cross-section and
insulated terminal clamps.
Non-insulated parts of the terminal clamps
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must not come into contact with other metal
parts while the jump lead/charging cable is
connected to the battery/jump-start connec-
tion point.
The jump lead/charging cable must not come
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into contact with any parts which may move
when the engine is running.
Always make sure that neither you nor the bat-
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tery is electrostatically charged.
Keep away from fire and naked flames.
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Do not lean over the battery.
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Observe the additional following points when
charging the battery:
Only use battery chargers tested and
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approved for Mercedes-Benz.
Read the battery charger's operating instruc-
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tions before charging the battery.