The 2011 BMW R1200RT has a CANBUS electrical system. This complicates adding electrical accessories like driving lights and phone chargers etc. to your motorbike. There are aftermarket devices that integrate into the CANBUS system to which you attach your accessories, however, they are expensive and, in my estimation, overly complex in usage. Histrionics are required to activate the accessory. For example, to turn on the phone charger you have to stand on the left foot peg, pull in the clutch and beep the horn twice. (This is an exaggerated and unfair characterization, but you get the idea.) I have enough trouble (not) remembering how to pair Bluetooth headsets such that any additional, obtuse controls would render me more useless than normal.
The alternative is to wire a conventional accessory power system that bypasses the CANBUS and draws power, through fuses, directly from the battery. I could have assembled one from scratch with a relay and fuse panel but I wanted something small and self contained. After much looking (where I'd been unable to find something suitable and been mystified why no electrical accessory manufacturer had produced one) I finally found a nice relay/fuse panel on aliexpress.
Inexpensive, aliexpress relay/fuse panel.
The stuff that came in the box.
DOA! Debugging revealed that this trace was cracked. A blob of solder fixed it.
All functioning now. A 20 AMP relay and the blue LEDs turn red if a fuse blows!
Laying things out, finding a secure spot and a source of switched 12V power. I run two conductor cables, +, -, from the fuse box to every accessory as opposed to relying on the frame for a ground.
The previous owner had mangled the rear Hella accessory plug's power cable (left rear of bike under passenger seat) with a Scotchlok connector. I used this wire as power source to control the relay. I hate Scotchloks. I yanked it, spliced, soldered and heat shrunk.
With everything zip tied in place and wired up. I ran three, two conductor 18 gauge cables in a protective sleeve up to the steering head. The fourth circuit will eventually go up and into the rear top case for charging USB devices while on the road.