My quest for the perfect (for me) tail bag has ended.! Touratech makes a great product! Things that work for me: yellow liner makes it easy to find stuff; tie down on top to put random stuff for quick access; inside pocket with velcro closure; waterproof zippers mean you don't have to put on a rain cover if your get caught in a downpour; comes with tie down straps; expandable; not to big, not to small, just right.
... to charge through the accessory socket. It'll digitally handshake and get the ECU to unlock the socket for ingress. The BMW charger has the BMW male connector already.