Support battery

Cars with Start/Stop function, in addition to the starter battery, are equipped with a 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 battery that helps during the Start/Stop function's starting sequence.

P5-1617-S90/V90 Support battery location
The support battery is located in a box next to the strut tower.

The following table shows specifications for the support battery.

Voltage (V)12
Cold start capacity1 - CCA2 (A)170
Size , L×W×H (mm)150×90×130
Capacity (Ah)10


When replacing the starter battery or support battery, a battery of AGM3 type must be fitted.


  • 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 starter 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 automatically4 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 starter 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 will continue to be activated. If the Start/Stop function then auto-stops the engine shortly after, there is a great risk that engine auto-start will fail due to insufficient battery capacity, because the battery has not had the opportunity to recharge.

If the car has been jump-started, or if there is insufficient time to charge the battery with a battery charger, the recommendation is to temporarily deactivate the Start/Stop function until the battery has been recharged by the car. In an outside temperature of +15 °C, 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.

  1. 1 According to EN standard.
  2. 2 Cold Cranking Amperes.
  3. 3 Absorbed Glass Mat.
  4. 4 Automatic starting can only take place if the gear lever is in neutral position.