Ultimate Luxeon K2 bike lights (in progress)
So after my recent set of mountain bike lights, I decided that I was ready to build what would be my be-all, end-all set of bike lights. These would be it. The Ultimate.
After the mountain bike lights, I wanted lighter, brighter, and longer battery life. I wanted to be able to use them for long road rides - so they can't use a bottle cage. I wanted to be able to commute without having to charge the battery every night. I wanted even more power for mountain bike riding and scaring pedestrians. I wanted lighter weight, so I could use them for fast group rides.
There are a number of bike light projects on this website:
|
The requirements that I wanted to meet were:
- Less than 200g weight for the whole system with an hour of battery life (at 3W output power)
- Light output competitive with a 20W halogen
- Batteries mounted somewhere other than the bottle cage
- A little light for the bike computer
- Some indication of the battery charge level
- Handlebar-mounted controls
- Robust design - nothing should be mounted purely with hot glue
So the big changes here are:
- Li-ion battery pack and charger. These are lightweight and have great energy density. I have a few packs - a small one for commuting and club rides, larger ones for endurance mountain biking, adventure racing, and Audax rides.
- Better LEDs and lenses. After playing with Cree XLamps, I decided that I'd be better off going with the most efficient LEDs I could find, even if it meant paying more. So I went with Luxeon K2 devices and the Fraen lenses I was using originally.
Hi Any more progress with
Hi
Any more progress with the K2 set up ? I've sweet talked my wife into getting me 2 K2 Luxeon stars & a Luxdrive 1000ma Powerpuck for christmas ( i did show her the lupine website but i think £600 for bike lights was a touch optimistic on my part) So boxing day i will be with soldering iron & all of the likely looking bits & pieces i can muster. Will keep you posted.
Oh and Good luck
any luck finishing this
any luck finishing this project?
I'd love to see it finished. Were you able to get the Luxeon K2 LEDs?
thx,
Pete
I wonder if you can advise
I wonder if you can advise me.
I have just bought a commercial light system which is running 3x luxeon III led's overdriven to 'nearly' 4W all running from a 16.8v Li-Ion pack. I have no other specifications sadly.
I was thinking of substituting in either a Luxeon K2 or Cree XR-E for one of my current led's to get some more light. Obviously the luxeon K2 star would be an obvious choice due to its similar specifications and same mounting plate. I'm not sure i would appreciate the difference though and am tempted by the higher output of the Cree XR-E. It should be able to handle the 4W ok but I am unsure what voltage/current is being delivered to the system.
I have no experience with constant current power supplies and am a little worried that changing a led will end up blowing it and (more importantly) the other two luxeon III's or even the power circuits. I presume the resistance of the led is the key here?
What would be your view on my little project? Worth a shot or just plain silly? :)
Cant wait to see how your system turns out.
Cheers
At a guess, I'd say that
At a guess, I'd say that your Luxeon III"s are being run at about 1A. Cree XR-E's should handle that. Most LEDs will tolerate overcurrent anyway if they're well heatsinked.
You should be able to just plug the XR-E's in in place. The main challenge then is the physical installation. If you've got Luxeon III Stars, you'll need to get a Cree 'Star PCB' and solder the LED onto that. If you've got Luxeon III Emitters, you'll need to figure out how to remove the old LED without damaging the board - which I expect will be challenging.
Constant current power supplies are just what they say - constant current. The resistance in the circuit is irrelevant because the power supply will adjust its output to always have the same current. This is assuming that it's using a constant current power supply at all, but odds are good that it is. Resistors are too wasteful to use in this sort of application.
I think it'd be worth a shot, but there is a significant amount of risk there. New lights with XR-E's are becoming quite affordable, so a brand new set might be a better option.
Very helpful
I have been on the hunt for a good LED homebrew system and you MTB system was one of the most straightfoward ones I have come across.
I would like to build a 300 Lumen system based on the Cree emitters so I was wondering how you build is going. Since it's winter here it's high on my list, but since your days are getting longer I imagine it is not on yours. Anyway, could I just modify your MTB schmatic and use Cree emitters with a regulator that allows either a 350 or 700 mA current?
Thanks either way.
Re: Very helpful
My MTB schematic uses older Cree emitters running at 700mA, so there's no reason you couldn't substitute the new XR-E's or something. The Buckpuck comes in 350mA and 700mA flavours to suit your project. If you're coming from Luxeon-land, the only thing to watch is that the Crees generally have a higher forward voltage - 4.5V instead of 3.5V. This is part of why they claim "highest light output at 350mA" - the total input power is significantly higher.
Due to my work situation, most of my riding happens late at night anyway - so it's both unpleasantly hot *and* I need lights!
Thanks, and good luck!
This was one of the most
This was one of the most helpful Homebrew LED sites that I have come across, so first let me say thanks.
How is the Cree build going, if you chose that route. I would like to build a system with approx 300 lumens total so 3 Cree emitters sounds like the ticket. Could I just drive it with the correct regulator and allow the 350 or 700 mA driver based on your MTB system?
Good luck and thanks.
Cree XLamp 7090 XR-E
The Cree XLamp 7090 XR-E is brighter than the Luxeon K2, and uses half the power. The only problem seems to be getting optics for them. Most of the available optics are intended for the 7090 XR which has a 100 degree beam, whereas the 7090 XR-E has a 75 degree beam. I've ordered some XR-Es and some lenses meant for the XR, and I'll see how well it works. I might end up having to wait another 3-6 months until the optics suppliers have new lenses available. I've probably used the same supplier as you, but I've had good service. They have been honest about delivery times and delays so far.
Regarding the difference in beam width between your commuting and mountain bike light, be aware that some optics are listed as full beam width, and some as half beam width. Some specify the beam width for monochromatic light. So the 6 degree Polymer Optics lens is actually 6 degree half angle, 12 degree full angle, and closer to 18 degree full angle with white light.
I've had a few people email
I've had a few people email me about the XR-E's - they're looking like a very good option right now. The K2's also don't gain a lot of brightness when you increase the current from 1A to 1.5A.
When time allows, I want to get a few combinations of LEDs and optics and see where the best combination of brightness/cost/power usage is.
I wasn't aware of the full beam width/half beam width difference - thanks for the info!
Any update?
I've been running with dual LuxeonIIIs with a buckpuck driver and 2 or 4 18650 Li-Ion batteries (with controller board from batteryspace) which was giving me a nice light and good runtime (8 hrs or so). I'm curious as to how you're pulling this off. More power is better, right?
Any update?
Well, not much progress has been happening lately, mostly due to being snowed under with work. I've been working on drivers for the Luxeon K2's, but I'm not even sure if I'll go that route at the moment. The K2's don't gain much light output once you go above 1A current. I've heard good things about the Cree XR-E's, so I might be playing with them next.
I do want to use my own driver board, if only for economy's sake. Buckpucks are horrendously expensive in Australia.
The li-ion cells are definitely something I want to integrate, regardless of the LEDs in use. My first prototype will probably have a single high-power LED (Luxeon K2 or Cree XR-E) and a pair of 18650 cells. I'll run two of them for mountain biking. But so far, I have no idea when I'll get a chance to look at it. It's just a dream for now!
Hey guys, I've just started
Hey guys,
I've just started making my own bike light but am rubbish at electronics..
I'm a CNC programmer by trade and have benn making some test bodies for mounting the LED's etc.
I've based the lights on 3 Luxeon K2's as they were available at the time.
Would any of you be able to give me some tips on the electronics side of things...maily what extra parts I would need, how to connect it all up.
That kind of thing.
Also, if someone could tell me how to attatch photo's I could post some of my CNC handywork...
Cheers, Steve