Boxerworks.com

Rob Frankham wrote: ↑Fri Nov 27, 2020 8:45 am

gspd wrote: ↑Thu Nov 26, 2020 3:48 pm Just a thought...
To increase cranking power, your starter relay is designed to cut power to the headlight circuit when the starter is activated.
You may be eliminating that function depending on where you intercept the headlight circuit for your new relay setup.
Make sure that it still functions correctly, or manually turn off your headlight before activating starter.

This doesn't actually apply to /5 models which have a very different starter relay and wiring. It could probably be done but it would need a study of the circuits to ensure that it didn't interfere with the starter interlock circuit.

Rob

I just took the headlight switch out of my /6 because it was giving intermittent contact to the lights, causing me to have a blinky headlight. New switchgear is $200ish.

On a /6, there's a headlight power relay already. Rather than sending the ground side of the switching circuit to ground, BMW sent the ground side of that circuit to the solenoid. Activating the starter cancels that ground path, shutting off the headlight. On my /6, the wire was already in the harness.

OP doesn't have that relay on his /5 to my knowledge. But perhaps he could wire the new relay(s) like that.

Melville said: "OP doesn't have that relay on his /5 to my knowledge.

To my knowledge, EVERY electric start bike has this feature.
Otherwise, the headlight consumed so much power they wouldn't start on cold mornings with the lights on.
It's possible the bike in question is an exception, it did come with a headlight on/off switch.
Does anyone remember the days when motorcyclists were deemed smart enough to know when their lights should be turned on or off?

The particular bike in question has a starter relay, right?
If you check the starter relay with a test light, most likely one of the terminals will have power when ignition is on, but no power when activating the starter. That's the headlight feed (or trigger for a load reduction relay).

gspd wrote: ↑Fri Nov 27, 2020 2:22 pm Melville said: "OP doesn't have that relay on his /5 to my knowledge.

To my knowledge, EVERY electric start bike has this feature.
Otherwise, the headlight consumed so much power they wouldn't start on cold mornings with the lights on.
It's possible the bike in question is an exception, it did come with a headlight on/off switch.
Does anyone remember the days when motorcyclists were deemed smart enough to know when their lights should be turned on or off?

The particular bike in question has a starter relay, right?
If you check the starter relay with a test light, most likely one of the terminals will have power when ignition is on, but no power when activating the starter. That's the headlight feed (or trigger for a load reduction relay).

I don't have a /5 to look at but according to the wiring diagrams, the power to the dip switch comes direct from the lighting position on the ignition switch. No load shedding relay at all.

The starter relay on the /5 is completely different from that on any other airhead, including as it does an electronic circuit that locks out the starter when the engine is running. This feature was abandoned with the /6 at the same time as the headlight load dumping function was introduced. I'm sure it would be possible to wire in a light relay to a /5 including this feature but I would be reluctant to do it unless I had studied the /5 sircuit to be sure that it wouldn't damage the starter relay... those things are not cheap. Of course, it wouldn't be that difficult to alter the whole wiring to the /6 setup or even the mono/R65 setup... but that's going a bit beyond this thread...

Rob

gspd wrote: ↑Fri Nov 27, 2020 2:22 pm Melville said: "OP doesn't have that relay on his /5 to my knowledge.

To my knowledge, EVERY electric start bike has this feature.
Otherwise, the headlight consumed so much power they wouldn't start on cold mornings with the lights on.
It's possible the bike in question is an exception, it did come with a headlight on/off switch.
Does anyone remember the days when motorcyclists were deemed smart enough to know when their lights should be turned on or off?

The particular bike in question has a starter relay, right?
If you check the starter relay with a test light, most likely one of the terminals will have power when ignition is on, but no power when activating the starter. That's the headlight feed (or trigger for a load reduction relay).

Before I eliminated the lightswitch from my /6, the headlight stayed on when starting if the switch was on. The switching side of the relay was completely independent of anything going on at the starter. The current setup, grounding the light relay through the starter, does turn the headlight off.

Sure would be nice if we could put an LED bulb in place of the power hungry H4 bulb. But I have never seen any mod like that.

Not for the /5, and way to expensive, but...

https://motodemic.com/shop/led-headligh ... -classics/

and here's a guy who mounted an LED bulb in an R100RT

https://www.youtube.com/watch?v=o9oTCLgSbr8

It won't fit most beemers, but I used one of these:
https://www.jwspeaker.com/products/led- ... olution-2/
They make round ones too, those could be made to fit any 'round' headlight model.
Super bright.


and added a motor from a remote car mirror to aim it.
https://www.youtube.com/watch?v=agz6NdvqQTE

You can get simple plug and play H$ LED replacements now... but be aware that they may not work well with the stock reflector abd may well be illegal in some jurisdictions.

Rob