Installing Battery Voltage Monitor & GPS adapter
Even with the OBC option riders of F658GS & F800GS twins are not able to monitor battery voltage. I was a bit disappointed by this omission as some other BMWs with the OBC do have a voltage display (650 XCountry as an example).
Anyway, since these bikes have a "modest" 400watt alternator and a dead battery means a dead bike I figured I'd add some type of voltage monitor.
After reviewing the various options I decided to go with the HEADS-UP LED Voltage monitor by SDC: http://www.signaldynamics.com/products/Modules/HUVM.asp
if above link does not work try this one:
The LED shows system voltage level in 5 steps:
Flashing Green - Voltage Above 15.25 VDC – This prolonged over-voltage condition can destroy batteries, especially gel-cells.
Steady Green - Above 12.9
Steady Amber - Above 12.6
Steady Red - Above 12.1
Flashing Red - Below 12 VDC – During this condition, if the engine is running, do not shut down until service can be provided. Restart of engine is unlikely. Reduce electrical load.
When powered up it goes thru a cute little boot-up showing off the various colors and then settles in based on the current voltage. For the first 10 seconds or so the LED is very bright, then it dims down a bit. It is very readable in all but the brightest sunlight but no so bright that it is annoying at night.
OK ... so cutting to the chase:
Let me recommend that you also review this article by twisticles which is very nicely done (a lot neater than mine will be):
The installation was really pretty straight-forward.
Here are the key components for the project:
The white plug with 3 yellow wires is the GPS adapter/repair plug which mates with the plug on the bike. Rob sells these in the F800Depot.com site.
The LED voltage monitor device - note the heat sink is rather large but i managed....
And last but not least by any means....
The key component of this project was a bracket I made with a friend's help.
(if you had not yet noticed that I get a bit "anal" about my bike you will have drawn that conclusion by the end of this article.... )
Anyway the custom bracket fits into the triangular shaped notch between the speedo. & tach. it is three sided and picks up as a mounting screw the screw on the back side of the tach. It was kind of a bitch to make....
Here's a slightly better view of the bracket - I apologize for the fuzzy pic. I didn't realize the pic. was a bit out of focus until the END of this project and I did not want to take the bracket back off. You can see the 1/4" diameter hole in the top triangular surface for the LED and the smaller hole on the bottom surface that bolts it to the tach. housing.
The bracket is fabricated from thin aluminum plate.
For better texture match to the rest of the instrument cluster I then sand-blasted the bracket and painted it with black rustoleum "texture" spray paint. (See there's that "anal" streak showing...)
Here is a shot of me starting with the wiring...
The BMW plug is the starter item, it has 3 wires - Ground, +12, and a speed wire that is not used (by me anyway).
Looking at the wires in the motorcycle side of the harness we have:
(1) Brown = ground
(2) Blue/Green = Speed Pulse
(3) Red/White = +12V
I soldered in the leads from the voltage monitor and also a 2nd pair of wires that I will use later when I install my GPS unit. The current draw from the monitor is very low, so I am not concerned about overloading the CAN-Bus electrical system.
The leads from the LED back to the heatsink with the actual electronics in it are about 18" long ... I wish they had been a bit longer as by the time I routed the wires down from the instrument cluster and along the frame of the bike I ran out of wire about here:
What you see there is a temporary tie-wrap that I installed while I considered my options.
The "rib" you see the heat sink attached to is the left side rib behind the side fairing which I removed for easier access to the guts of the bike. I also removed the windscreen to get better access to the instrument cluster.
I ended up sticking the heatshink onto the inside surface of the rib with the double-face tape provided in the kit and then also tie-wraping it to the rib for extra security.
Below you see the finished result - the extra LED lines up nicely with the existing lights and does not look too "home made".
A couple of notes:
1) The provided GPS plug is connected to the CAN-Bus so no fuse is needed... well that's what I understand to be true ;-)
2) The plug stays live for about 60 seconds after the key is turned off, so if you are double-checking your voltages or something remember the wires are live for a bit after the key has been turned off!
3) Note that when the top panel is re-installed that the lighter plug "uses up" pretty much all the space that exists below and to the left of the ignition key, so route your wires accordingly.
4) If your battery is weak at the end of a ride as result of running your gloves and your vest and your GPS and your coffee-cup warmer, beer cooler, or whatever .... you CAN turn off your headlight and let the bike idle for a few minutes with reduced load to top off the battery.
HOW do you turn off the headlight you may ask?
1) Press and hold the cancel-turn-signal button for ~6 seconds (you know 1001, 1002, 1003, .....)
2) Press and hold the right turn signal button until the headlight goes off.
It will stay off until you turn off the bike or move the bike with the engine running.
I'm really pleased with how it came out, I could have been done in 30 to 45 minutes but ... routing the wiring to my personal satisfaction and applying the heat shrink tubing to the soldered connections and .... takes longer if you are a perfectionist, so I think it took me about 2 hours not counting bracket fabrication time.... which as I said was NOT easy due to the complex shape and tight tolerances needed to make it nestle snugly into the "niche" between the tach. & speedo.
Well I'll shut up now.
Last edited by jrwooden; 11-15-12 at 07:04 PM.