Busch Müller Luxos hack question

siltsunrise

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May 11, 2018
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Hi, I was on here a bit years ago, but lost my user info, so new account.
I'm still a noob, in any case.
I have a BUMM Luxos U which is making me a bit nuts. It doens't think I have the wits to know when it's dark out, so turns itself on randomly, often, even in broad daylight.
Not the end of the world, but I'm hoarding all that precious power to charge devices and drive a speaker while I tour. And because of said speaker, I can't see when the bloody thing has turned itself on again without standing up off my recumbent.

BUMM is giving me the runaround, and because I bought it 2nd hand, I may not even be able to warranty it (german law - buyer has to do it - he's long gone).

Soo, does anyone who's gutted this thing think there's any chance I could snip something inside it to simply disable the stupid auto-on feature altogether?

Bonus questions: -
- Who makes the best version of the e-werk type gadget (usb charge port from a dynamo) these days, if I decide to ditch this thing.
- What's a good light to replace the Luxos? I love how it shines to the sides mightily; very very handy when I'm scouting for campsites after dark. I just like it. Something with a similar wide beam very preferable.

Thanks mucho!
 

angerdan

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Feb 12, 2015
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290
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Europe
  1. Does anyone who's gutted this thing think there's any chance I could snip something inside it to simply disable the stupid auto-on feature altogether?
  2. Who makes the best version of the e-werk type gadget (usb charge port from a dynamo) these days, if I decide to ditch this thing?
  3. What's a good light to replace the Luxos?

  1. mtb-news.de/forum/t/einfacher-umbau-des-busch-mueller-luxos-auf-cree-xm-l-fuers-e-bike.789761/page-2#post-15051678
  2. B&M offers the best solution AFAIK.
  3. B&M IQ-X.
 

samsavvas

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May 11, 2017
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I'm not that familiar with the Luxos although a friend has had one from new and had multiple problems with it - mainly of a mechanical nature (it fell to bits). So my first question (and my apologies, it'll sound like I'm asking a very obvious one) is, 'can you turn the 'auto-on' function off?' That is, is there a switch that has an extra position for the ambient light-controlled auto-on function? If so, just make sure it's turned off. If there is a switch and it's malfunctioning then maybe you can figure out a fix to ensure it's turned off permanently.

If there isn't a switch then I suspect that if you look inside there may be a photocell somewhere that performs the auto-on function. If you can see it (or it's switching circuit) then maybe you can simply bypass it by shorting it out.

Don't ditch the Luxos yet, especially if you like the beam. A by-pass fix is likely to be a fairly elementary. The trick is going to be finding the photo-cell and then figuring out the best way to short it or its circuit out. I'm hoping that Steve or one of CPF's other resident electronic whizzes will chime in and offer something more at this point...

But I'd also second Angerdan's recommendation of one of the newer lights such as the B&M IQ-X. The new SON light also looks really nice as does the Spanninga Axendo which is a somewhat-cloned revision of the fantastic Phillips Saferide.

Regarding dynamo-powered charging set-ups, I've found these two sites quite useful:

https://triduffer.wordpress.com/2016/04/19/the-great-dynamo-usb-power-run-off

&
https://www.cyclingabout.com/list-of-hub-dynamo-power-supplies-for-usb-devices

I really like the look of the Forumslader (available in kit form) as well as the Igaro, Kemo and Sinewave.

Sam.
 

Steve K

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Jun 10, 2002
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2,786
Location
Peoria, IL
......


Don't ditch the Luxos yet, especially if you like the beam. A by-pass fix is likely to be a fairly elementary. The trick is going to be finding the photo-cell and then figuring out the best way to short it or its circuit out. I'm hoping that Steve or one of CPF's other resident electronic whizzes will chime in and offer something more at this point...

.....
Sam.

Without a schematic, it's hard to offer much advice.
About all I can provide is the characteristic of a typical CdS (cadmium sulfide) photocell. I've used one by Advanced Photonix Inc, and its resistance decreases when it is illuminated. As such, if you wanted it to think that it was always had light shining on it, you would want to either short it out, or wire a resistor in parallel with it.
If you wanted it to think it was always in the dark.... then I'd just put some black tape over it.
 

gewe

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Dec 6, 2002
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Netherlands
I have the Luxos B on my bicycle. The light does not have a real on/off switch. It is just a push button, that signals the light should switch state (from on to off, or from off to on). In order to do that, the electronic circuit in the light needs power. That power comes from a supercapacitor, which is charged by the dynamo. If the bicycle isn't used for a longer period (several days?) the supercapacitor is empty. When I start cycling, the light sometimes is on. Maybe the circuit does not initialize properly.

My son's bicycle has a Luxos B as well. This one is a few years older (bought in 2013 IIRC), and it does not show this behaviour.
 

tspoon

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Apr 4, 2004
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I had a Luxos U which would intermittantly show the same fault. It seemed to get worse in cooler, damper weather, making me suspect that dew was forming somewhere it shouldn't and causing problems. My light eventually failed completely. I was, at the time, pretty disappointed that a light costing so much could be so poorly designed (Do they not have rain in Europe?). I never sent it back due to being on the other side of the world, and also due to it being a basic design fault that replacement could not properly rectify.

However, if yours has not yet failed, I recall finding pages with information from others noticing the same fault, who then tried to improve the seal of the light fitting, with varying levels of success. You could give that a go.
 

gewe

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Dec 6, 2002
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My Luxos showed different behaviour for about a week or two. When starting to ride, the light would switch on. No matter how many times or how long I pressed the switch, it stayed on (despite hearing and feeling the click of the switch). After that period it stopped doing that. Luckily it switches on when I press the switch. :)
 
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