Triple Cree XR-E Bike Light

[nightrider]

hey, I just noticed this http://myfwyc.org/Timberlake/CreeLEDLight/IMG_1992

now.... how good/bad is it against luxeon Lottery ?

Good Job by the way

Thanks ViReN.

Yeah, one of the Crees was definitely more yellow and not as bright as the other two. Keep in mind, that shot was at very low drive power (just enough to light the LEDs), so it tends to exaggerate the yellow tint of the one LED. But even at full power (if you can look at it for long), it's not as white as the other two. Since the Crees were mounted on stars that did not have binning info on them I don't know if they were all supposed to be of the same tint or not. I suppose the bin info is on the back of the emitter? All the Luxeon stars I've ever seen have the bin printed on them.

 

[Sawtooth]

I think that as long as the LEDs stay fairly cool, it will have minimal impact... but big deal if my Crees last only 25,000 hours as opposed to 50,000 hours! I imagine I will be moving on to the next generation of LEDs looong before these start to loose brightness.

Excellent point nightrider! I agree totally... (On the other hand if they only last dozens of hours at 1A that would be bad...)

 

[Pinter]

I'm testing an XR-E at 1000mA on my bike.
After 17h30m there is no measurable brightness loss on it.

When in motion there should be no problem with overdriving them.

Headwind makes the heatsink cool; only a few degrees above the ambient.
I use my 20W led-array (mostly inefficient Luxeons) on a relatively small (2.6"x2.6") heatsink and it only gives a mildly warm feeling for my frozen fingers even after a half hour continuous usage.

 

[srvctec]

nightrider,

Some really cool stuff here! I just clicked on the link in your sig line, wound up here and decided to post. This is far to good of a thread to let it disappear into oblivion!

 

[nightrider]

nightrider,

Some really cool stuff here! I just clicked on the link in your sig line, wound up here and decided to post. This is far to good of a thread to let it disappear into oblivion!

Thanks man, I really appreciate that!

 

[nightrider]

Nice job. I bet it gives those $300 HID setups a good run for the money.

Thanks CM. It definitely puts out some lumens, but it's still not quite up to par with the HID bike lights. We're getting closer though. I keep meaning to take some comparison beam shots with some of my riding buddy's L&M HIDs, but I keep forgetting to take my camera & tripod when I go riding.

- Allen

 

[sfCyclotourist]

I noticed that you mounted the Cree LEDs to the housing you constructed using Arctic Alumina Adhesive. In your write-up, you mentioned the importance of the fact that the AAA is non-electrically-conductive. I'm planning on mounting my LEDs (on stars) using small screws and some AA Ceramique thermal paste, so they can be removed if/when I want to upgrade to whatever the next generation of LEDs might be. Do the Cree star-mounted LEDs need to be electrically isolated from the heatsink?

Thanks!

 

[nightrider]

I noticed that you mounted the Cree LEDs to the housing you constructed using Arctic Alumina Adhesive. In your write-up, you mentioned the importance of the fact that the AAA is non-electrically-conductive. I'm planning on mounting my LEDs (on stars) using small screws and some AA Ceramique thermal paste, so they can be removed if/when I want to upgrade to whatever the next generation of LEDs might be. Do the Cree star-mounted LEDs need to be electrically isolated from the heatsink?

Thanks!

Yes, I believe most stars are isolated, but it seems like I've heard of some that are not (MCPCB experts chime in here). Also, with a variety of 3rd party manufacturers making the Cree stars, you might just want to check for lack of continuity to either of the emitter's leads with a meter, just to be safe.

That said, sometimes, screws will get in the way of mounting a lens or reflector against the surface of the star. I used the Ledil lenses that mount flush against the surface of the star. I had to grind away part of the back of the lens to accomodate for my wires and solder glob. Using screws with those lenses will require a good deal of material to be removed. Depending on what lens or reflector you choose, this may or may not be a problem.

One other point. It is possible to pop-off stars that have been AAA'd to your light (usually without even damaging them). I've done it on several ocassions with no problem.

 

[sfCyclotourist]

...you might just want to check for lack of continuity to either of the emitter's leads with a meter, just to be safe.

That said, sometimes, screws will get in the way of mounting a lens or reflector against the surface of the star....

One other point. It is possible to pop-off stars that have been AAA'd to your light (usually without even damaging them). I've done it on several ocassions with no problem.

All good points -- I was just thinking that the screw heads might get in the way of the stick-on optics (I'm using the OPTX collimators that Cutter sells, they have an adhesive backing similar to the Ledil's). I'll check the contacts on my LEDs with a meter, great idea. I also didn't realize that AAA was somewhat non-permanent! That simplifies things quite a bit. At the very least, maybe I'll glue the LEDs to an aluminum plate, and then mount the plate with screws to get them away from the optics...

Thanks!!!

 

[nightrider]

I just popped a few Luxeon III stars off an older light yesterday. I just took a sharp knife edge and placed it behind the glued star, then tapped the knife with a hammer and wedged the star off. Just have to do a little scaping, sanding and cleaning then glue new stars on. Old stars are undamaged.

I guess if you were gonna be changing the stars frequently, for purposes of trying different bins etc, it might be a better idea to mount them with screws and heatsink compound if they didn't get in the way of your lens/reflector.

 

[nightrider]

BTW, I'm currently building a Triple Seoul P4 (Ubin) bike light.

I had the three Seoul emitters (not stars) but, I used one of them to upgrade my Fenix L1T (which turned out great by the way). Anyway, I went ahead and mounted the other two and tried some different reflectors (cutoff IMS 20).
Here are some beamshots:
(all at the same manual setting 1/4sec, F2.8, ISO 200)

First, my Fenix L1T w/SSC P4 (u-bin) upgrade. It's really nice now and I chose to leave the beam more floody than spotty.

Next is the Dual SSC P4 (u-bin) with chopped IMS 20s @ 1A. This will be a triple SSC P4 when I get another emitter (which is on order).

Finally shown is the Triple Cree bike light of this thread @ 1A.

Beamshots are always fun. The Cree is a nice bright light, especially at one amp. Although I still would like more spill from it, I'm very happy with it as a bike light for trail riding.

I'm liking the spill that I'm getting from the SSC P4s using the IMS 20 reflectors. I've sanded about 3mm off the front (not the base) of the reflectors. I'll start a new thread in a few weeks when I finish the Triple Seoul P4 light.

 

[Calina]

If you want more spill. have you tried to use one led without optic or reflector?

If so ,I would love to see a beam shot of that as I would like to build a double Cree or SS bottle dynamo driven bike light.

 

[chris_m]

I noticed that you mounted the Cree LEDs to the housing you constructed using Arctic Alumina Adhesive. In your write-up, you mentioned the importance of the fact that the AAA is non-electrically-conductive. I'm planning on mounting my LEDs (on stars) using small screws and some AA Ceramique thermal paste, so they can be removed if/when I want to upgrade to whatever the next generation of LEDs might be. Do the Cree star-mounted LEDs need to be electrically isolated from the heatsink?

I'm almost certain that they don't need electrical isolation. Normally with an MCPCB the only thing that might have an electrical path to the MCPCB itself is the slug of the LED, and with a Cree LED that is electrically isolated. It would be a very strange MCPCB indeed that allowed conduction from one of the power leads of the LED to the core - they will be routed on top of a thin insulating layer.

 

[nightrider]

If you want more spill. have you tried to use one led without optic or reflector?

I think that's a little too much spill. and very little throw. You need a little of both, but it's always a compromise.

If so ,I would love to see a beam shot of that as I would like to build a double Cree or SS bottle dynamo driven bike light.

I'll see about taking a shot without reflectors (they are attached with silicone caulk) next time I do some beam shots.
Good luck with the dynamo light... I don't know much about that but have seen a couple of threads around here on the topic.

 

[nightrider]

I'm almost certain that they don't need electrical isolation. Normally with an MCPCB the only thing that might have an electrical path to the MCPCB itself is the slug of the LED, and with a Cree LED that is electrically isolated. It would be a very strange MCPCB indeed that allowed conduction from one of the power leads of the LED to the core - they will be routed on top of a thin insulating layer.

Looking back in my notes I found this from the Luxeon III Star datasheet:

"3.Electrical insulation between neighboring Stars is required —aluminum board is not electrically neutral."

So not all stars are electrically isolated. Maybe that's where I developed my isolation paranoia.

I know we're talking Cree stars here and the back heatsink area of a Cree XR-E emitter is electrically neutral, but given the fact that the stars are coming from several sources and that there are positive and negative contact areas on each side of the back.. you never know that some star provider might think it perfect sense to let the negative side connect to the back of the star? For some applications, that might seem ideal (screw it down to ground and have one wire to solder. Certainly not good for connecting stars in series, however.

Anyway, I agree with Chris, all the Cree stars that I've run across, so far, seem to be electrically islolated.

 

[chris_m]

The reason for the problem with Luxeon Stars is that the slug on these LEDs isn't electrically neutral. For best heat transfer, the stars have the slug in direct electrical as well as thermal contact with the MCPCB core.

However it's actually harder to make stars with a direct electrical path from the slug (or any of the other contacts) to the core - most of those for the Cree even have an insulating layer there (and hence worse thermal performance). I can see no reason at all for a MCPCB manufacturer to go to the extra effort required to make one of the elctrical paths connect with the core of the PCB, so it's simply not going to happen.

 

[aljsk8]

nightrider

simple question

how thick is the aluminium tubing?

i can get it with 3mm walls but im guessing i wont fit the stars
under that (19.5mm internal)

thanks

Alex

 

[Stregone]

What kind of current draw do you get at the battery? I just ordered the LEDs and optics to make on of these. I probably won't need a whole lot of runtime, so I'm thinking about using some AA or even AAA batteries. Later after I get more into night I think I will probably make a C pack (~5000mah).

 

[Bikecop]

nightrider

simple question

how thick is the aluminium tubing?

i can get it with 3mm walls but im guessing i wont fit the stars
under that (19.5mm internal)

thanks

Alex

I made a similar light using the nightrider model. The tubing I purchased at the local Lowes measures 1.48mm thick.

 

[decerebrated]

nightrider, your a bloody ledgend.
My parts arrived from Cutter today and I,ve just finished putting together a rough single light version to see how best to assemble it.
I've bought a Ledil smooth spot, a Q2 bin XR-E and a 1amp Buckpuck. I already have a couple of Sanyo Li-ion batteries that are hooked up to provide 7.4v @ 2.5 amps which should be good for a few hours.
The light output is stunning
The light weighs next to nothing and with a battery pack that only weighs 120gr ? I wont even notice it.
Thanks again for the inspiration.
now to do a neat job of this and then I might make up another light using this triple http://www.cutter.com.au/proddetail.php?prod=cut607&cat=12 with some SSC's if they will fit.

Cheers

Geoff :twothumbs