Mercedes-Benz GLA Operator's Manual page 318

Jump-starting
316
Do not start the vehicle using a rapid charging device. If your vehicle's battery is discharged,
the engine can be jump-started from another vehicle or from a second battery using jumper
cables. Observe the following points:
The battery is not accessible in all vehicles. If the other vehicle's battery is not accessible,
R
jump-start the vehicle using a second battery or a jump-starting device.
You may only jump-start the vehicle when the engine and exhaust system are cold.
R
Do not start the engine if the battery is frozen. Let the battery thaw first.
R
Only jump-start from batteries with a 12 V voltage rating.
R
Only use jumper cables which have a sufficient cross-section and insulated terminal clamps.
R
If the battery is fully discharged, leave the battery that is being used to jump-start connected
R
for a few minutes before attempting to start. This charges the battery slightly.
Make sure that the two vehicles do not touch.
R
Make sure that:
the jumper cables are not damaged.
R
bare parts of the terminal clamp do not come into contact with other metal parts while the
R
jumper cables are connected to the battery.
the jumper cables cannot come into contact with parts which can move when the engine is
R
running, such as the V-belt pulley or the fan.
Secure the vehicle by applying the electric parking brake.
X
Shift the transmission to position P.
X
Turn the SmartKey to position 0 in the ignition lock and remove it.
X
Switch off all electrical consumers, e.g. rear window defroster, lighting, etc.
X
Open the hood.
X