PEUGEOT 3008 2017 Handbook page 260

In the event of a breakdown
Access to the battery
The battery is located under the bonnet.
For access to the (+) terminal:
F unlock the bonnet by activating the internal
release lever, then the external safety catch.
F lift the bonnet, then fix it in place with its rod.
(+) Positive terminal.
It has a quick-release clamp.
(-) Negative terminal.
As the battery's negative terminal is not
accessible, a remote earth point is placed near
the battery.
258
Starting using another
battery
When your vehicle's battery is discharged, the
engine can be started using a backup battery
(external or from another vehicle) and jump
leads or using a battery booster.
Never try to start the engine by
connecting a battery charger.
Never use a 24 V or higher battery
booster.
Check beforehand that the backup
battery has a nominal voltage of 12 V and
a capacity at least equal to that of the
discharged battery.
The two vehicles must not be in contact
with each other.
Switch off all the electrical consumers
on both vehicles (audio system, wipers,
lighting, etc.).
Make sure that the jump leads are not
close to moving parts of the engine (fan,
belts, etc.).
Do not disconnect the (+) terminal while
the engine is running.
F Lift the plastic cover on the (+) terminal, if
your vehicle has one.
F Connect the red cable to the positive
terminal (+) of flat battery A (at the metal
elbow) then to the positive terminal (+) of
backup battery B or the booster.
F Connect one end of the green or black
cable to the negative terminal (-) of backup
battery B or the booster (or an earth point
on the other vehicle).
F Connect the other end of the green or black
cable to earth point C on the broken down
vehicle.
F Start the engine of the vehicle with the
good battery and leave it running for a few
minutes.
F Operate the starter on the broken down
vehicle and let the engine run.
If the engine does not start straight away,
switch off the ignition and wait a few moments
before trying again.