If both the starter battery and the hybrid battery are discharged then both batteries must be charged. In such a case, charging only the hybrid battery first is not possible.
In order for the hybrid battery to be charged the starter battery must have a certain state of charge.
The hybrid battery must only be replaced by a workshop - an authorised Volvo workshop is recommended.
The hybrid battery's cooling system has a separate expansion tank.
The hybrid battery's coolant must only be topped up by a workshop - an authorised Volvo workshop is recommended.