# Cree XR-E (R2) or XR-C direct driven at 2+ amps



## troller_cpf (Sep 8, 2010)

Hi there folks!
I was wondering what would be a good battery set up to DIRECT DRIVE a Cree XR-E (R2) or a Cree XR-C (which one of the two has the highest surface brightness) at about 2 - 2,2 Amps (I think they can still handle that current, I do not need thousands of hours of working life, I may just need one hundred... so even more amps if they can handle it )

What battery setup should I put back? Assuming that I have a Mag 1,5D or 2D body...

thanks!

BTW: are there any drivers that can drive up to 2+ amps for a cree led?


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## -Gast- (Sep 8, 2010)

I dont think that they will handle 2A... They will get blue and darker...


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## LEDninja (Sep 8, 2010)

When a LED is overdriven, it turns blue and dies in minutes not a hundred hours.

Here is JTR1962's testing of an XRE-R2.
https://www.candlepowerforums.com/posts/2412997&postcount=158
At 2A the LED produces 390.87 lumens.
Here is JTR1962's testing of an SSC-P7 bin D.
https://www.candlepowerforums.com/posts/2784484&postcount=257
At 2A the LED produces 559.51 lumens. *168.64 lumens more than the XRE-R2.*
The XR-E is very efficient *AT 350 mA ONLY*. They do not work very well at 2000 mA. For 2A you should get an LED that works well at 2A or above. (SSC-P7, Cree MC-E, Luminus SST-50)

In the olden days LED Vf was 3.6 to 4 volts. So 3 freshly charged NiMH at 4.05V or an RCR123A at 4.2V can run them relatively safely. New LEDs are 3.2 to 3.4 volts Vf and are less tolerant to the higher voltage of freshly charged batteries.
So you have to be careful to properly heatsink the LED.

The best mod for beginners is a 3D P7 Mag.
https://www.candlepowerforums.com/threads/238641
For a Mag 1D you can use 3AA to 1D adapters and Eneloops/Duraloops. The KD ones tend to melt under high current conditions so get fivemega or mdocod ones.
https://www.candlepowerforums.com/posts/3326024#post3326024
For a 5D Mag build a 2D battery spacer/dummy cell to turn it into a 3D Mag.
For a 2D Mag Use 3C cells. You can use a piece of plastic pipe instead of the aluminum tube Elektrolumens used.
https://www.candlepowerforums.com/threads/194716

there are plenty of drivers available from the sandwich shoppe or KD.


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## troller_cpf (Sep 8, 2010)

thanks for the info, but I'd like to drive hard the XR-E R2 to get max throw for a flashlight mod with a 3" aspherical head (I've already done one... you can see my other threads), but I wanted to get the most out of the R2 to have the max throw...


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## fyrstormer (Sep 8, 2010)

If you want to get maximum throw, it might be better to use an emitter with a wider die and higher current capacity, use binary optics (two lenses) to focus the die image the same way a microscope would. Trying to drive a tiny die with a huge amount of current will not work, because the phosphor coating simply doesn't have the durability to stand up to that much heat. Even with a Peltier cooler, the materials inside the LED may not be able to conduct heat away from the phosphor fast enough to keep it from burning.

EDIT: Actually, you know what, forget my second suggestion, it's just too risky.


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## ejot (Sep 8, 2010)

No reason to abandon the overdriven XR-E plan. It's an excellent choice. 


But there are serious obstacles to achieving 2A direct drive. Similar discussion with some excellent thoughts and data here. As for a driver to get you there, tough one. Looks like the TaskLED hipFlex might work. Granted, in an unusual/inefficient application. 


And sheesh, it's a $5 emitter, not a first-born child. OP's target is clearly surface brightness over efficiency. Sounds like this build is the "push the boundary" / "because I can" type, so, have some fun! Push a few really hard, burn 'em up! :devil: Only then can you dial it back and confidently say, "_This_ is where I want to run, _this_ is my optimal point given the goals for this project." 
IMO/$0.02/YMMW etc. etc.


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## qwertyydude (Sep 9, 2010)

I've done 2 amps before on an xr-e but even with ideal heatsinking, a lapped solid copper cpu heatsink with fan cooling attached to a lapped star and I only got about 1 hour of continuous use before the phosphor turned brown and it dimmed, never turned angry blue though cause it stayed cool. But I don't think the smaller xr-c could even take the current. I'd stick with a maximum 1.6 which is what I run my HS-802 at since it is completely safe with good heat sinking.


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## saabluster (Sep 9, 2010)

qwertyydude said:


> I've done 2 amps before on an xr-e but even with ideal heatsinking, a lapped solid copper cpu heatsink with fan cooling attached to a lapped star and I only got about 1 hour of continuous use before the phosphor turned brown and it dimmed, never turned angry blue though cause it stayed cool. But I don't think the smaller xr-c could even take the current. I'd stick with a maximum 1.6 which is what I run my HS-802 at since it is completely safe with good heat sinking.


Your problem is you used a star. I wouldn't even run at 1.6 with a star. Solder the LED straight to copper and it should be able to handle 2A for a much longer time.


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## -Gast- (Sep 9, 2010)

saabluster said:


> Your problem is you used a star. I wouldn't even run at 1.6 with a star. Solder the LED straight to copper and it should be able to handle 2A for a much longer time.


Thats it... You can use the best surfaces for your cooler and star but the star is the problem... if its not a copper star...


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## bshanahan14rulz (Sep 10, 2010)

Copper star is still a star.... all it does is get in the way of the heat.


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## Illum (Sep 10, 2010)

bshanahan14rulz said:


> Copper star is still a star.... all it does is get in the way of the heat.



thermal bottleneck...its worse if its an aluminum star with a PCB lining:shakehead

EDIT: just noticed, CREE specifies the absolute maximum at 1000ma


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## degarb (Sep 28, 2010)

I take it Troller hasn't replied because he went to rehab? Probably a flashaholic, due to the four pots of coffee a day habit. But, hey, maybe he will invent something like the non conductive water cooling system for leds.


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## Illum (Sep 28, 2010)

degarb said:


> I take it Troller hasn't replied because he went to rehab? Probably a flashaholic, due to the four pots of coffee a day habit. But, hey, maybe he will invent something like the non conductive water cooling system for leds.



nonconductive and noncorrosive...I'm thinking glycol:twothumbs


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## bigchelis (Sep 29, 2010)

Scott made a Surefire L1 Exteme with copper heatsink and DD at 2A it pulled off a incredile 390 OTF and 14.5K lux at 1m.

Recently; I got a 2D Mag with XR-E R2 DD off 3 NIMH C cells. It pulls 2A~2.2A and no tint change. The heatsink is aluminum on this one, but its almost a 2in slug heatsink. 

bigC


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## f9bob (Oct 18, 2010)

I have done thermal image on XR-E Q4 array of 12 led(Par 38) running on 468mA with Aluminum heat sink with Flir I7 camera.Thermal image has been taken after 8 hours run.I have come to conclusion that heat dissipation can be achieved maybe with Nuventix jet fan only efficiently if you intend to run on higher current led XR-E.Even with that I don't believe in huge gain in sense of efficiency and lumen output.


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