CREE R5 driven at 1050mA vs 1400mA

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Budgeteer
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CREE R5 driven at 1050mA vs 1400mA

I was wondering how much would increase an R% led output by changing driver from 1050mA to 1400mA (the triple amc vs quad amc linear regulator). Also how much would heat increase (would a p60 host be appropriate?!?)? It is worth it or it is just a few lumens more?

kragmutt wrote:

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Don
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325% of base output vs. 250%. Say 348 lumens at 1A, vs. 450 lumens at 1.4A

 

http://www.cree.com/products/pdf/XLampXP-G.pdf

Page 6

 

I'd say 30% is worth it if you can lose the heat.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Tido
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According to the datasheet (http://www.cree.com/products/pdf/xlampxp-g.pdf), the relative luminous flux at 1A is ~250% (350mA being 100%). At 1.4A it's ~320%, so you get a 28% increase in output. How much output you get in reality depends on how good the heat sinking works. Output decreases with higher junction temperatures and pushing more current through the LED will produce more heat.

From personal experience I can say that an XP-G R5 is noticeably brighter at 1.4A than it is at 1A and won't overheat in a good P60 host.

Budgeteer
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Ok thanks both. Now the question No.2. Lets say i do whatever it is possible to aid the p60 heatsinking... how hot should be the p60 host for me not to worry?

kragmutt wrote:

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Don
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Almost imposible to say. But it is very hard (Probably impossible for ordinary people) to measure the actual junction temperature.

 

There is no way that any production light manages to keep the junction temperature to 25oC.

 

The better it can lose heat, the better it will perform.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Budgeteer
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I was hoping to improve heatsinking to max and then judging by host temperature. I know it isn't reliable at all but should give me a rough indication if the led is going to melt or not. One of my TR-801 modded with ak-47 is getting uncomfortably hot to hold after 30min sitting on head on my desk. Wodering if its going to die that way...

It is just me or R5 at 1-1,1A are noticeably colder than Q5 or it is just TR-801 poor heatsinkig that makes such a difference?

kragmutt wrote:

They're gonna send you a green redcat with a black LED.

Don
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At the same current an R5 will produce a lot less heat, and a lot more light than a Q5

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Budgeteer
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As i suspected, thanks for clarifying. I like both but like R5 alot better than Q5 though they are really a different beast. Always been more prone to floodier lights but i can still appreciate a nice recoil thrower.

kragmutt wrote:

They're gonna send you a green redcat with a black LED.

agenthex
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I use folded and flattened aluminum foil to wrap the modules in to help conduct heat. The difference is significant.

 

Also, btw, the faster a light heats up, all things being equal (especially terminal temp), the better it's heatsinked. If it takes 30min for the body to reach steady state temp, it probably means the other end is searing hot.

Reading this makes you smarter: http://lesswrong.com/

Budgeteer
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I use the aluminum foil trick too. About the 30 min... i just tested it after 30min upon retrying it was that hot after 12-14min... very unconfortably hot.

kragmutt wrote:

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Wow what a difference. I switched on 2 TR-801 for 15-20 min and they a re noticeably less hot as usual. I think they are about 1/4 less hot. All this just by having them tail standing instead of head standing (or it is sitting in this case :D).

kragmutt wrote:

They're gonna send you a green redcat with a black LED.