As you may know, I just bought a BMW S1000R.  Although it may seem like an S1000RR that they just deleted some plastic from, it's way more different than you might think.

The other night, riding some Mexican backroads in the dark of after midnight (my first ride after dark on the new bike) I became aware of, and puzzled by, the bike's light setup. 

Now, the S1000RR that I had before this had normal current-fashion dual headlight.  One side was the low beam, and the other side the high beam.  When the engine runs, the low beam is by default always on.  Hit the high beam switch, and presto, the high beam also lights up.  As it should.

The headlights are a little different on the single R.  It has a projector-lens high beam instead of the more typical style of the double R.  The high beam itself does a decent job of throwing the light down the road, but that isn't the weird part.

Watch this video (yes, it's a crappy cell-phone video from an odd angle, but you'll see what the issue is anyway):

http://youtu.be/2oCB_PuMECM

When I turn the high beam on, all is well and good- for about two seconds, and then the low beam kicks off.  The little bit of light you see in the low beam housing is the 5W parking light.  I turn the high beam off, and the low instantly returns to action.  High beam again, and the low kicks off after two seconds.

Looking closely at the video, it seems as if the high beam steps up in intensity a little bit when the low shuts off but I'm not sure how effective that is, since it's a plain old ordinary 55W H7 halogen.

Now, returning to an important fact I mentioned earlier, the double R did not do this sort of behavior.  It had no problem with both H7 bulbs at full blast, so I have a hard time imagining that this odd behavior is intended to compensate for weak alternator output.

Thoughts?   Theories?  Crackpot conjectures?  I'm open to any of them.  Also, and this is more important, any suggestions on how to get this bike to exhibit normal (both beams on when high is turned on) behavior?


Thanks in advance for your brilliant input.

It's a thought.   

Do the S1000Rs in other parts of the world do this too or is this just due to USDOT BS lighting regulations?

Are they both halogen bulbs? I could understand it if the high beam was an HID, and the low had a delay built in for when you waited for the HID to spool up, which could be even more pronounced in cold weather. Turning the high beam off, no delay, as the HID shuts down immediately.

Not sure how this would play with the Can-Bus BUT

Might try and run a diode between the hot (voltage supply) to the high beam and the hot (voltage supply) to the low beam. That way when the hight was turned on it would power the low as well. 

The Ducati designs headlight kit on the ST4 powers the headlights directly off the battery, and uses the stock headlight wiring to trigger the relays. Perhaps something similar would work.

Quote from: Andrew on April 23, 2014, 09:35:42 PM

Not sure how this would play with the Can-Bus BUT

Might try and run a diode between the hot (voltage supply) to the high beam and the hot (voltage supply) to the low beam. That way when the hight was turned on it would power the low as well.

This was suggested to me.  My concern is that the ECU on this bike keeps track of everything imaginable and some things that aren't, and would undoubtedly throw errors and refuse to work if I try anything like that.




When I take the bike in for its 600 miles service I'm going to talk to the mechanic about it and ask if there's anything that can be done along those lines.  Perhaps a secondary power supply to the low beam triggered by a relay off the high beam, or something like that.   

Your concern may be valid. The canbus will detect upper and lower limits, and anything outside that will trigger a fault and the circuit will be shut down.

Not my explanation, but someone who has done a bit a research:

It does that by measuring the voltage across a shunt inside the module and only allows a certain voltage window.

The upper threshold was at about 6.2A @14.2V. The threshold is probably somewhat lower while the alternator gets to full output. During this time the current rises (for about 2-3sec after crank). The lower threshold was at 0.86A @14.2V. So, the current must be between these two values to be acceptable for the central controller.

Using a relay to switch battery directly to the lamp will work if you have a resistor in parallel to the relay coil of about 14.2V/0.86A = 16 Ohms to satisfy the minimum threshold. Maybe 15 Ohms to be on the safe side. At 14.2V this resistor "consumes" 14.2Vx14.2V/15Ohms = 13.5Watts. Make sure that the resistor has adequate cooling surface.

Quote from: Mr. Whippy on April 24, 2014, 04:43:14 AM

Does the low beam actually add anything to the light pattern when it's on?  Broaden the beam for example? If lo beam adds little, you may be better off adding driving lights rather than messing with the stock headlight harness.

The effect, when riding along a dark Mexican back road in the small hours of the morning was that the low beam was good, but when I turned the high beam on the world was suddenly a bright, cheery place for two seconds.  Then the low kicked off and it seemed as if I could still see Bott's dots a mile down the road but I couldn't see details of the pavement right in front of me.

Yes, I am planning on installing driving lights, but I'd like to get the stock lighting situation fixed first, then start adding additional lighting.

Yea.  The low beam on a lot of bikes seems to be nice and floody, letting you see the sides of the road well, while the high beam is more projector/spot light  in function.  If CANBUS were to be a problem, you could always wire a secondary circuit to the lo's (or high's) and have a separate switch to turn them on...

I have a PDM-60 on order already.