Mercedes-Benz C-Class (W205) 2015 - 2021 Owners Manual: Notes on starting assistance and on charging the 12 V battery

Mercedes-Benz C-Class (W205) 2015 - 2021 Owners Manual / Breakdown assistance / Battery (vehicle) / Notes on starting assistance and on charging the 12 V battery

Vehicles with a lithium-ion battery

When charging the battery and during starting assistance, always use the jump-start connection point in the engine compartment.

NOTE Damage to the battery from overvoltage

When charging using a battery charger without a maximum charging voltage, the battery or the on-board electronics may be damaged.

Only use battery chargers with a maximum charging voltage of 14.4 V.

All other vehicles

When charging the battery and during starting assistance, always use the jump-start connection point in the engine compartment.

NOTE Damaging the battery through overvoltage

When charging using a battery charger without a maximum charging voltage, the battery or the vehicle electronics may be damaged.

Only use battery chargers with a maximum charging voltage of 14.8 V.

WARNING Risk of explosion from hydrogen gas igniting

A battery generates hydrogen gas during the charging process. If there is a short circuit or sparks start to form, there is a danger of the hydrogen gas igniting.

Make sure that the positive terminal of the connected battery does not come into contact with vehicle parts.
Never place metal objects or tools on a battery.
When connecting and disconnecting the battery, you must observe the described order for the battery clamps.
When giving starting assistance, always make sure that you only connect battery terminals with identical polarity.
During starting assistance, you must observe the described order for connecting and disconnecting the jumper cables.
Do not connect or disconnect the battery clamps while the engine is running.

WARNING Risk of explosion during charging process and starting assistance

During the charging process and starting assistance, the battery may release an explosive gas mixture.

Avoid fire, open flames, creating sparks and smoking.
Make sure that there is sufficient ventilation during the charging process and during starting assistance.
Do not lean over a battery.

WARNING Risk of explosion from a frozen battery

A discharged battery may freeze at temperatures slightly above or below freezing point.

During starting assistance or battery charging, battery gas may be released.

Always thaw a frozen battery out first before charging it or performing starting assistance.

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 vehicle nor charge the battery.

The service life of a battery that has been thawed may be dramatically shortened. The starting characteristics may be impaired, especially at low temperatures.

It is recommended that you have a thawed battery checked at a qualified specialist workshop.

All vehicles

Plug-in hybrid: observe the notes in the Supplement.

Otherwise, you may fail to recognize dangers.

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 to start the engine.

Observe the following points during starting assistance and when charging the battery:

Only use undamaged jumper cables/charging cables with a sufficient cross-section and insulated terminal clamps.
Non-insulated parts of the terminal clamps must not come into contact with other metal parts while the jumper cable/charging cable is connected to the battery/jump-start connection point.
The jumper cable/charging cable must not come into contact with any parts which may move when the engine is running.
Always make sure that neither you nor the battery is electrostatically charged.
Keep away from fire and open flames.
Do not lean over the battery.

Observe the additional following points when charging the battery:

Only use battery chargers tested and approved for Mercedes-Benz.
Read the battery charger's operating instructions before charging the battery.

Observe the additional following points during starting assistance:

Starting assistance may only be provided using batteries with a nominal voltage of 12 V.
The vehicles must not touch.
Gasoline engine: Only accept starting assistance if the engine and exhaust system are cold.

Notes on the 12 V battery

Starting assistance and charging the 12 V battery

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