Volvo XC40 Owner's Manual page 559

Support battery
Vehicles with the Start/Stop function are
equipped with two batteries – a more power-
ful 12 V start battery and a support battery
that provides stronger current during the
function's start sequence.
The 12 V support battery is located in the engine
compartment. The start battery is also shown here
(top).
NOTE
The higher the current consumption in
•
the vehicle, the more the alternator has
to work and the batteries have to be
charged = increased fuel consumption.
When the starter battery capacity has
•
dropped below the lowest permissible
level, the Start/Stop function is disen-
gaged.
When the Start/Stop function is temporarily
reduced due to high current consumption:
The engine will auto-start, even if the
•
driver does not lift their foot from the
brake pedal.
The support battery does not normally require
more service than the start battery. If you have
any questions or concerns, consult a work-
shop ‒ an authorized Volvo workshop is rec-
ommended.
CAUTION
If the following is not observed, the Start/
Stop function may temporarily stop work-
ing after connection of an external starter
battery or battery charger:
The negative battery terminal of the
•
vehicle's starter battery must never be
used to connect an external starter
battery or battery charger – only the
vehicle's negative charging point
should be used as a grounding point.
MAINTENANCE AND SERVICE
NOTE
If the starter battery has been discharged
to the extent that the vehicle does not have
normal electrical functions and the engine
must then be jump-started with an external
battery or a battery charger, the Start/Stop
function may remain activated. If the Start/
Stop function shortly thereafter auto-stops
the engine, there is a huge risk that auto-
start of the engine will fail due to insuffi-
cient battery capacity since the battery had
not had time to recharge.
If the vehicle has been jump-started or if
there has not been enough time for the
battery to be charged with a battery
charger, the Start/Stop function should be
temporarily deactivated until the battery
has been recharged by the vehicle. At an
ambient temperature of about +15°C
(about 60°F), the battery must be charged
by the vehicle for at least one hour. At
lower ambient temperatures, the charging
time can increase to 3-4 hours. It is advisa-
ble to charge the battery with an external
battery charger.
Specifications for support battery
Type
Voltage (V)
AGM
12
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