I have a cig. lighter on pigtail plugged into the factory accessory plugin under the seat. I just run the pigtail into one of the saddlebags and plug the phone in. When not needed I unhook it and keep it in the saddlebag. The acc. plug is controlled by the left hand switch on the Road King nacelle. Not sure if the FB had the acc. attachment under the seat or not.....
If you have a Beltran Battery tender, they make a connector that plugs into the pigtail that is attached to the battery. My FLHR has wires off the back of the headlight I was able to use for power.....
Thanks I do have a HD pigtail and a battery tender. I also have a ram mount to hold the phone on the bars not so sure I want the cord running all the way back where the tender sticks out behind the seat.
Don't know if you have saddlebags, but my battery tender pigtail goes right out the side of the seat, and then I use a phone charger (made by battery tender) to plug in phones and other items which are in my saddlebag. No long cords to worry about dangling under the tank or near the hot engine. I've attached a pic of the battery tender charger which is about $12 or so online. The only downside is you can't immediately view those items as you are riding.