Volvo S80 Owner's Manual page 100

If for some reason the battery in your car is discharged, you can "borrow"
current from a spare battery or another car's battery to start the engine.
Always check that the clamps are secure so that there are no sparks
during the start attempt.
To avoid the risk of explosion, we recommend you do exactly as follows.
· Turn the ignition key to position 0.
· Ensure that the booster battery has 12 volt current.
· If the booster battery is in another car, stop the engine of that car and
make sure the cars are not touching.
· Connect the red cable to the booster battery's positive terminal
(1+ in the illustration) and the connection in your cars engine
compartment (2+ in the illustration).
The clamp should be attached to the contact point located under a little
black cover with a plus sign on it. The cover is connected to the cover
of the fuse box.
Remember that batteries, especially the booster battery, contain
oxyhydrogen which is highly explosive. A spark, which can be caused
if you incorrectly install the jump leads, is enough to cause the battery
to explode and both damage the car and injure you. The battery also
contains sulphuric acid, which can cause serious corrosive damage. If
the acid comes into contact with your eyes, skin or clothes, flush with
large quantities of water. If acid splashes into your eyes contact a
doctor immediately.
· Connect one end of the black cable to the booster battery's negative
terminal (3– in the illustration).
· Connect the other end of the black cable to a grounding point on your
3100088m
car (4– in the illustration).
· Start the engine of the "booster car". Let the engine run a few minutes
at a speed slightly higher than idle, 1500 rpm.
· Start the engine of the car with the discharged battery.
· NOTE! Do not move the clamps during the start attempt (risk
of spark buildup).
· Remove the clamps in reverse order.
NOTE! If you need to help another car, connect the red cable as shown in
the illustration above. Connect the black cable between two grounding
points as also shown in the illustration. Do not connect the black cable
to the negative pole of another battery!
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