VW Phaeton GP0 5.0 V10 Built 2005 201567Km Hello dear Phaeton driver, I have a little problem to which I have unfortunately not found something really helpful here, so I try to explain it. And I installed a USB socket in the glove compartment about two weeks ago. I connected it to the power supply from the CD changer. (No ignition plus) In retrospect this was probably a very bad idea. but since the installation I had already the problem that in the instrument cluster on the Volt display only about 12 volts, with running engine in the stand, were displayed to me. When giving gas or while driving it kept to 14 volts. meanwhile it is only unfortunately that I was sucked the battery completely to 0 volts at the distance of about 5 days. In the meantime it almost always kept to 14 volts and fell only sporadically to a maximum of 10 volts. In other words, everything turns off electronically and I only drive in the emergency run program if it falls below about 6 volts.. To describe the problem more precisely or to understand. Let’s go about the fact that both batteries are fully charged in the trunk. If I turn on the ignition now the instrument cluster 14 volts (in my case about 12.5 (too low…) are displayed. When I start the motor the voltage sometimes keeps itself for a few kilometers constant to 12.5 volts and f If I repeat this process, it always happens the same thing, so it can not actually lie on the alternator, because the starter battery is obviously still charged. When measuring directly on the battery, it also shows 13.5 volts. However, when measuring during the start-up, it falls to 9 volts. The parallel circuit also seems to work, because otherwise the comfort battery would not work. The comfort battery is also brand new and about 3 months old. I’ve already read it out with OBD Eleven. It shows 9 errors, which is no wonder when the battery is dead. I didn’t have a fault for my problem that could be responsible for it. I hope I could explain it to some extent intelligibly. I very much hope that anyone can help me, because in my vicinity the workshops are my trust is fully booked until after Easter and I can’t go on like this. Thank you in advance!