I just received this from Warm & Safe (the originators of electronic thermostatic controllers). If you need to charge a USB device, you might want one: http://www.warmnsafe.com/12v-to-5v-3a-usb-adapter/. It appears to me that you'd also need one of these http://www.warmnsafe.com/bmw-plug-to-coax-jack-18-inch-adapter-cable/ to make it all work.
I am not related to the company in any way, though I can confirm that Warm and Safe makes great stuff.
