A device and method for synchronization of data for audio and/or video between a memory of a device in a motor vehicle and an external device is provided. The method comprises synchronizing the data between the memory and the external device through a radio connection through a synchronization unit. The method further comprises outputting a status signal (St) based on a charge state (C) of the first power source by a monitoring unit to the synchronization unit and signaling from the synchronization unit to the external device an interruption of the synchronization due to low charge level. The method further comprises terminating the synchronization of the data based on the status signal (St) indicating that the charge state (C) of the first power source is below a threshold (th) and/or that a second power source for charging of the first power source is disconnected from the first power source.