L.E.D. vs HALIDE/T5/VHO

[OceanicCorals-Eugene-]

Originally Posted by StirCrazy

actualy a temp of 50 degrees is well with in the specs that the LEDs are rated at so they should do better than the rated hours and less intensity drop that the spec since the specs are at 80 degrees.

A running temp of 50C it is still within the range of acceptable temperature for the LEDs. They are spec to run at 50-80C max but with cooling you can actually prolong the life of the LEDs and get less intensity drop over the claimed 50,000hrs life of the emitters.

I agree with you that it would be nice to have a silent system, but in the long run i just dont know if its worth it, i mean we can get more life/intensity out of the LEDs if they were active cooled than passively cooled so why not do so and gain an extra few years more out of them.

You've got some good points there Steve, it'll be interesting to see your project on the LEDs too

[bakaichi]

i thought i might put this on

Normal running temp for the CooLED at room temp of 23 C is about 50~55C

just by simply adding a computer fan to help heat dissipate, the temp is down to around 37~39



Pic here you can see the fan and the light operation.

The heat sink, pluse a little bit of active cooling decrease the running temp but a lot .


~~

[OceanicCorals-Ian-]

Here is a recent quick review of the LED Aqua Illumination module. Note the PAR comparison.



http://reeftools.com/news/aqua-illum...ar-led-system/

[StirCrazy]

Originally Posted by OceanicCorals-Ian-

Here is a recent quick review of the LED Aqua Illumination module. Note the PAR comparison.



http://reeftools.com/news/aqua-illum...ar-led-system/

yup, nice output but there 24" is from the top of the aquarium, they forgot to include the 2" the modual is above the tank so there 12 and 24" measurments should actualy be labled as 14 and 26.

Steve

[Lampshade]

For Cooling check out this online calculator:
http://www.novelconceptsinc.com/calc...resistance.cgi


Cree has a page regarding thermal management:
http://www.cree.com/products/pdf/XLa...Management.pdf
And their page about XP-E's:
http://www.cree.com/products/pdf/XLampXP-E.pdf

Sooooo.... I'm planning on a build with 120 LED's. The Thermal Resistance in the LED's are 9°C/W(XP-E Blue/White) and a good junction to the heatsink is 1°C/W per LED i can calcualte the minimum heatsink resistance needed driving them at 750mA at an ambiant 30°C(my house has AC, should never get that high). Thermal resistance is how much hotter something gets to disapate 1W of heat, so lower is better for a heatsink.

Aluminum is about 237 W/m*K at 26 Celcius.(wikipedia)

Use the formula for Heat from cree:
Tj = Ta + Ptotal (Rth j-sp/ NumLED + Rth sp-h + Rth h-a)
P = 120*.750A*3.25V = 292.5W
Rth h-a = (145°C - 30°C –9°C/W x 292.5W/120 – 1°C/W x 292.5W/120)/292.5W = 0.31°C/WIn

I need a min 0.31°C/W heat sink.

Using the calculator on novel i can find the size i need to meet that. I used the slab calculator and the one linked above and came up that a 10"x42" heatsink with 1" fins and .25cms of air flow, asuming .25cms average flow over the entire thing, 1 computer fan is .25, it would probably take 2 to make this consistant. This would have a C/W of : 0.0653926108°C/W, far more than needed.

Couple other pages for info on Cooling LED's:
http://www.qats.com/cpanel/UploadedP...a_0909_web.pdf
http://sound.westhost.com/heatsinks.htm

[mseepman]

Originally Posted by Lampshade

For Cooling check out this online calculator:
http://www.novelconceptsinc.com/calc...resistance.cgi


Cree has a page regarding thermal management:
http://www.cree.com/products/pdf/XLa...Management.pdf
And their page about XP-E's:
http://www.cree.com/products/pdf/XLampXP-E.pdf

Sooooo.... I'm planning on a build with 120 LED's. The Thermal Resistance in the LED's are 9°C/W(XP-E Blue/White) and a good junction to the heatsink is 1°C/W per LED i can calcualte the minimum heatsink resistance needed driving them at 750mA at an ambiant 30°C(my house has AC, should never get that high). Thermal resistance is how much hotter something gets to disapate 1W of heat, so lower is better for a heatsink.

Aluminum is about 237 W/m*K at 26 Celcius.(wikipedia)

Use the formula for Heat from cree:
Tj = Ta + Ptotal (Rth j-sp/ NumLED + Rth sp-h + Rth h-a)
P = 120*.750A*3.25V = 292.5W
Rth h-a = (145°C - 30°C –9°C/W x 292.5W/120 – 1°C/W x 292.5W/120)/292.5W = 0.31°C/WIn

I need a min 0.31°C/W heat sink.

Using the calculator on novel i can find the size i need to meet that. I used the slab calculator and the one linked above and came up that a 10"x42" heatsink with 1" fins and .25cms of air flow, asuming .25cms average flow over the entire thing, 1 computer fan is .25, it would probably take 2 to make this consistant. This would have a C/W of : 0.0653926108°C/W, far more than needed.

Couple other pages for info on Cooling LED's:
http://www.qats.com/cpanel/UploadedP...a_0909_web.pdf
http://sound.westhost.com/heatsinks.htm

Great links on this. Have you started your LED build yet? How big is the tank you're building over?

[lastlight]

Lampshade you should put together an online calculator for all that. Be a huge hit with the DIY LED crowd. Nicely done!

[Lampshade]

No start on a LED build yet... I've been doing a "bit" of research on this so i can justify the nearly $2000 expense. looks good so far, I'll probably start with some suppliment lighting to my MH's and eventually replace them. The tank's a 150gal 6" long, so i was planning on a fixture that size(10x48) and 40° optics, possibly 60°. Should get decent spread, i just want to avoid the zebra color's like i've seen some people have with 40° optics.

As for an online calculator, probably a good idea, haha, maybe i could get vertex or even cree to give me product for advertisements :P.