HOW TO: Add power outlets
Thought I chime in with my "how do I power electrical things" solution for the 790 Duke.
I looked at the PP USB power option which connects to the side of the headlight but decided against it - I wanted power front and rear for one thing and didn't particularly like the bracket or the USB's low power rating.
So I settled on using SAE connectors - they are the kind of connectors used by some battery chargers and also by a few solar systems for DC connections. They are nice and cheap so I bought a pack of 6 blank SAE pigtails off Amazon, the ones I got are about 1 foot (30 cm) long.
They have a waterproof (with cap) SAE connector on one end and plain wire connectors at the other - you need to add some 6mm spade connectors on the bar ends to connect to the wire harness - best to do this with a good crimper.
For neatness I cut some short heat shrink tubing to dress the ends - put this on before you crimp naturally - and apply heat from a heat gun or hair drier to shrink onto the wire/crimp connector after.
I also wrapped the whole length in wiring harness tape for a good look - it's a cloth material that sticks to itself.
At the rear, under the pillion seat at the side of the battery are two sets of connectors just peeking out: ACC1 & ACC2. They are spade socket connectors in clear rubber shrouds. ACC1 is always on and ACC2 comes on with the ignition - plug the SAE connector into whichever suits you.
Similar connectors are at the front of the bike behind the headlight cowl.
You completely undo the headlight adjuster screw at the top of the headlight and the headlight unit tilts forward. The screw is captive so won't fall out - I counted the turns so I could put it back without realigning the headlight after. Unplug the headlight connector on the back and then the headlight can tilt all the way forward down and rest on the mudguard/fender.
Behind the headlight you will find a plastic cover held on with three screws, one at the top and two at the bottom - undo these and remove the cover. You will find the front ACC1 and ACC2 connections on the left hand side - they are the same spade sockets as at the rear, same wiring colouring too.
I fed my pigtail down from behind the dash following existing cables and plugged it in keeping the wiring tidy and out the way. Make sure that the SAE connector up top has enough play to hide under the handlebar riser.
Put the cover back on with the three screws and swing the headlight unit back up, connect the headlight connector and push the headlight all the way back up into place then screw the headlight adjusting screw back in with the same number of turns as you used to remove it.
It's easier to do in practice than actually write this - the photos should make it clearer
To convert this all to useable USB power I bought an "OptiMate O100 SAE USB Charger 2400mA" from Amazon too. This lives under the rear seat until I need it along with any USB cables.
The thing I like about this is that it delivers lots of power (~10W) and is smart - it knows when then engine is running and when the engine is stops it only supplies power for a further 3 hours then cuts out so it can't drain your bike battery. I also measures battery health too.
All you need now is a USB cable to connect whatever device you need to charge / power. I have a small flexible rubber one for the front (6 inches / 15 cm) - this connects to my phone mounted on a QuadLock bracket attached to the handlebars.
I hope this is useful for folks!