The nice thing about this device is that it is fed directly from the iPod / iPhone, that you do not need power cables. If the player stops playing (if you paused or the album / playlist is by) the transmitter switches off after a while. You can also charge via an included cable the player while driving, but it must not (as with many other devices). This also the battery is indeed protected by the iPod. And finally I can also make calls while driving back (with headset ;-) without this noise on the radio.
All in all, exactly what I what I was looking for. Thank You!