Support battery

Cars with the start/stop function are equipped with two batteries - one more powerful 12 V starter battery for starting and one support battery that helps during the function's starting sequence.
P5-1817-S/V60-Support battery in engine compartment
The 12 V support battery is located in the engine compartment.
P5-1917-XC90-48V battery
If the car is equipped with a 48V support battery instead, it is located under the cargo area. The box over the 48V support battery must only be removed by an authorised workshop.


High voltage can be dangerous in the event of incorrect intervention. Do not touch anything on the batteries that is not clearly described in the owner's manual.

  • 48 V support battery must never be used for jump-starting.
  • External electrical equipment must not, under any circumstances, be connected to the 48 V battery.
  • The 48 V battery may only be serviced and replaced by a workshop – an authorised Volvo workshop is recommended.


  • 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 disengaged.

Temporarily reduced Start/stop function due to high current take-off means:

  • The engine starts automatically1 without the driver depressing the clutch pedal (manual gearbox).
  • The engine starts automatically without the driver lifting his/her foot off the foot brake pedal (automatic gearbox).

The support battery normally requires no more service than the normal starter battery. A workshop should be contacted in the event of questions or problems - an authorised Volvo workshop is recommended.


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.


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 temperature 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 temperature, 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

Voltage (V)12
Cold start capacity2 - CCA3 (A)170
Size, L×B×H150×90×130 mm (5.9×3.5×5.1 inches)
Capacity (Ah)10


If the battery is replaced, make sure you replace it with a battery with the same size, cold starting capacity and type as the original battery (see the decal on the battery).
  1. 1 Automatic starting can only take place if the gear lever is in neutral position.
  2. 2 According to EN standard.
  3. 3 Cold Cranking Amperes.