Volvo XC90 2018 Owner's Manual page 609

Support battery
Cars with the Start/stop function are equipped
with two 12 V batteries - one extra powerful
starter battery for starting and one support bat-
tery that helps during the function's starting
sequence.
The support battery is located in a box next to the strut
tower.
NOTE
The higher the current take-off in the car,
•
the more the alternator must be working
and the batteries charging = Increased
fuel consumption.
When the capacity of the battery has
•
fallen below the lowest permissible level
then the Start/stop function is disen-
gaged.
Temporarily reduced Start/stop function due to
high current take-off means:
The engine auto-starts without the driver lift-
•
ing his/her foot from the foot brake pedal.
The support battery normally requires no more
service than the normal starter battery. A work-
shop should be contacted in the event of ques-
tions or problems - an authorised Volvo workshop
is recommended.
IMPORTANT
If the following instruction is not observed
then the Start/stop function may temporarily
cease to work after the connection of an
external battery or battery charger:
The negative battery terminal on the car's
•
starter battery must never be used for
connecting an external starter battery or
battery charger – only the car's negative
charging point may be used as the
grounding point.
MAINTENANCE AND SERVICE
NOTE
If the starter battery has been discharged so
much that the car has no normal electrical
functions and the engine is then jump-started
with an external battery or a battery charger,
the Start/stop function may continue to be
activated. If the Start/stop function then auto-
stops the engine shortly afterwards, there is a
great risk that engine auto-start will fail due
to insufficient battery capacity, because the
battery has not had the time to recharge.
If the car has been jump-started, or if there is
insufficient time to charge the battery with a
battery charger, the Start/stop function is
temporarily deactivated until the battery has
been recharged by the car. In an outside tem-
perature of approx. +15 °C (approx. 60 °F),
the battery needs to be charged for at least
1 hour by the car. In a lower outside tempera-
ture, the charging time may increase to
3–4 hours. The recommendation is to charge
the battery using an external battery charger.
Specifications for support battery
Type
Voltage (V)
Cold start capacity A -
B
CCA (A)
AGM
12
170
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