Did the TFT bought for the car. (On the packaging, the device is shown installed in the headrests.) According to the manual festhalten- withstand the unit tensions betw. 11.5 and 13.5 volts -Please. About 13.5 volts, it can be destroyed. The charging voltage of the alternator is about but at 13.8 to 14.4 volts. How pray tell does it work to use only when the engine is ??????? Could I therefore additionally before friemeln a voltage regulator, thank you. 0 stars