getting the most out of Cree's XR-E R2 - driver suggestions?

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sixfink
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getting the most out of Cree's XR-E R2 - driver suggestions?

Howdy all,

 

for half a year, the parts intended for my first flashlight mod are accumulating dust on the shelf, and it's about time to tie up some loose ends and ask a couple of questions to finally get started.

I had bought four Cree emitters (XR-E R2, half a year ago they looked quite promising!), and according to the data sheet they run on a Vf of 3.7 volts @ 1000 mA. Heatsinking is not considered a problem.

I don't know yet whether to run them parallel or in series. I guess driver availability will answer that for me, as 4000 mA constant current drivers seem to be either scarce or expensive. No multi modes or PWM on this build. According to the driver list on this site's sticky topic, TaskLED made a couple of 1000 mA constant current drivers, but (besides the steep price) those either seem to be sold out or discontinued. Same with Assembled Shark/ Remora UI.

The only ones left on my list are Shark (providing 980 mA constant current) boost driver from Sandwich Shoppe and the buck driver 4-pack from DealExtreme (which is listed at 930 mA in the sticky list, but only rated at 800 mA on the DealExtreme website. I'm a bit cautious because a single Shark is four times as expensive as four buck drivers from DealExtreme. Other than brand names, is there a difference in quality and reliability?

I am thinking about using 6 volts as a power source, either by 2 x CR123A or 4 x AAA (I know, that must sound weird, but the host body is quite spacious so I can stack cells in homegrown adaptors for added capacity). Maybe even eneloops or 16340 rec, dunno...

Am I missing anything important? I do have the strange, nagging feeling that I have missed something...

 

What is your opinion considering price, availability and reliability? Or should I look at something completely different (besides scrapping the Crees in favor of a bunch of SST90)

 

Thanks a lot,

 

Simon

 

 

Edited by: sixfink on 03/16/2011 - 08:34
Match
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What host do you plan on putting 4x R2's in?  If you can, series is the way to go to avoid uneven current sharing. Your battery options are doable with the right driver, but you'll be looking at short runtimes.  Also, one R2 driven at 1A will still create a fair amount of heat, much less 4 of 'em. I guess I'd help if we knew what torch you'll be using and what you expect the intended use to be.

brted
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You could drive 4 LED's with a 2800mA driver, so 700mA each, getting 200 emitter lumens out of each LED. That's not too shabby. Might be easier to to find a reflector for 3 of them though. Most of the power is still converted to heat, so even 2.8A times 3.7V is over 10 watts, almost all of which will be heat that has to be dissipated.

xP.1337
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or piggy back two shiningbeam style 2800 ma drivers and over drive them.

 

from my experience, the q5 can take a bit of overdriving with ease.

of course if thats the case that might be better for 5 R2s.... imo

sixfink
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Howdy back and thank you,

 

The host is a ABS-bodied Fulton (always had a soft spot for those). Not the brightest idea considering effective heatsinking, I know; but I haven't intended this light for long runtimes anyways, maybe one minute at a time.

The intended purpose is merely to turn it into something very bright (relatively); a conversation piece, to showcase the possibilities of modern LED technology.

Advantage: readily available, cheap, decades of reputation, and it'll hold a variety of configurations of cells, from 2x 9volt over 6x AA (or CR123A) to 8x AAA using custom battery inserts. The head offers enough space for four emitters, LEDil 9° optics and 1-1/2" of aluminum heatsink.

The only bit still missing is an appropriate driver which is

1) reliable,

2) can deal with my crazy power input ideas while maintaining constant current for the emitters

 

Simon