I'm thinking of building an LED fixture little by little and need help...

[STiTCH87]

Well i'm doing 24 3w LEDs and if possible don't want to run the fans.

 

[Cheetos]

im going to test some extra thick u channel tonight that i bought on ebay, i plan on putting about 20 watts through 3 ft

I'm running 24 watts through 6 ft of u-channel and it only gets up to 82 degrees after several hours. I thought it would actually be a little warmer. I would imagine you will be alright with the 20 watts across 3 ft.

 

[Cheetos]

Well i'm doing 24 3w LEDs and if possible don't want to run the fans.

I would think with the individual heatsinks that you want to use you should be okay without a fan but I would plan on one if they will be enclosed in something. You still need some kind of airflow to cool down the heatsink.

 

[focus]

It's junction temp you need to be concerned with not heat sink or j/u channel temps.

 

[Cheetos]

It's junction temp you need to be concerned with not heat sink or j/u channel temps.

82 on my setup is the junction temp measured with a infrared non conductive thermometer! Obviously, if the heatsink or channel is allowed to get warm then the junction temp will be higher.

 

[focus]

Wow with no fans unreal.

I built mine years ago worked wonderful, used the JBJ fans though.. check this thread on NR for a little overview I also used 24 leds.

http://www.nano-reef.com/forums/index.php?showtopic=177446&st=20

 

[Bobbofin]

I'd do a 24" x 7.280" heatsink with 24 lights in a 8 x 3 grid with 2.5 spacing and 70° optics. 4" spacing at the center brace. 14 blue and 10 whites. You can buy the whole set up for about $300 from reefledlights.com. http://www.reefledlights.com/led-kits/deluxe-led-kits/ Just ask for a differant heatsink.

 

[STiTCH87]

I'd do a 24" x 7.280" heatsink with 24 lights in a 8 x 3 grid with 2.5 spacing and 70° optics. 4" spacing at the center brace. 14 blue and 10 whites. You can buy the whole set up for about $300 from reefledlights.com. http://www.reefledlights.com/led-kits/deluxe-led-kits/ Just ask for a differant heatsink.

Wow, that is almost EXACTLY what I plan to do! Same site and everything. Still not sure if I wanna use that heatsink or individuals though. Cuz I REALLY like the appearance of that picture I posted before, and not a fan of the chunky heatsinks with fans many people build.

 

[Bobbofin]

Heat is the enamy of LEDs. The cooler the better. Anything over 90° is bad, very bad. You won't get the recommended life out of them if they over heat. I have a large heatsink and four 80mm fans. My fixture never gets over 75° when tested with infared temp gun. Perfect!

 

[Cheetos]

Heat is the enamy of LEDs. The cooler the better. Anything over 90° is bad, very bad. You won't get the recommended life out of them if they over heat. I have a large heatsink and four 80mm fans. My fixture never gets over 75° when tested with infared temp gun. Perfect!

Actually, it's anything over 100 degrees Celsius.

 

[STiTCH87]

Are you sure Cheetos? Cuz I doubt an LED would ever go over 212 degrees farenheit. I don't even know if MHs get to that temp.

So what you're saying bobbo is that I shouldn't go with individual sinks? Isn't there a heat gun I can borrow from BRS? Cuz I may build with individual first to test the heat and then if it's not good i'll go with a fullsized heatsink. I just find them really ugly.

 

[Cheetos]

Run a Cree XRE at 1 amp with no heatsink and watch how hot it gets. I've seen LEDs get as high as 135 celsius so yeah I'm sure!

 

[Bruno]

Just put 2 of these in and your done!!! J/k it would just a tad bit to hot lol

100W White High Power LED
$199.99
100 Watt High Power Bright White LED. Ideal for making light sources for video camera, fish tank, car, pool and RC Toys. Quantity: 1pc Lens Color: Water Clear Emitted Color : White DC Forward Voltage (VF): 30~35 Vdc DC Forward Current (IF): 3800mA Viewing Angle: 140 Degree

•Intensity Luminous (Iv): 6000~7000LM
Color Temperature:

•6000~6500K White

 

[STiTCH87]

DAAAMN! Lol. I could maybe run to mounted to my ceiling and bleach some sps with it. Not that i'd notice any bleaching since I myself would be BLIND!

That's awesome. Hah.

So individual heatsinks in circular shape with vertical fins likely WON'T keep my LEDs cool enough is what you're all saying? What if I do that and use two fans aswell?


Also still looking for an answer to if it's possible to wire the fans into the circuitry of the LEDs so they share plugs instead of having 4 power cords. Trying to keep this fixture at 2 cords if I can.

 

[Cheetos]

You could defitely do that if you run fans. If you go with buckpuck drivers and a 24 volt power supply you can run 2 fans in series with the drivers.

 

[STiTCH87]

What if I go with mean well dimmable drivers?

I was gonna go with two Mean Well ELN-60-48Ds

 

[Cheetos]

If you go with the meanwells you will need a separate power supply for the fans. You can't run fans off the meanwells.

 

[STiTCH87]

Are buckpucks dimmable? I don't really care what the drivers are as long as one can run 12 LEDs and a fan, and is dimmable.

Do you think i'd need 2 fans, or should just one fan suffice?

 

[Cheetos]

There are dimmable pucks. You can run 6 LEDs per puck and up to 6 pucks per 24 volt power supply. I would imagine you would want the blue and whites on separate power supplies so you have plenty of room to run fans off of one of the power supplies. You would need either two 12 volt fans or one 24 volt fan. HTH!

 

[STiTCH87]

Damn you really know your LEDs! Talk about helpful info. So i'd do 2 pucks and a fan on one 24v supply. Times two. Correct?

Any suggestions on what puck(s) to use?