(Another) DIY LED Build - Linear Design

[TheFishMan65]

I am not a thermodynamic person but as I understand.
You want lots of surface area to get rid of the heat to the air. The Aluminum only needs to be thick enough to move the heat through the channel. Since fins on a CPU heat sink are pretty thin I expect 1/10 - 1/8 would be fine.

 

[TropTrea]

I am not a thermodynamic person but as I understand.
You want lots of surface area to get rid of the heat to the air. The Aluminum only needs to be thick enough to move the heat through the channel. Since fins on a CPU heat sink are pretty thin I expect 1/10 - 1/8 would be fine.

Yes the way heat is dispensated is through surface area. Volumn basicly has very little effect other than slowing the heating or cooling. So idealy the thinner the material and more surface are it had the better. However unless your spacing your LED's closer than 2.5" apart 2" channeling without fans is adequate. Heat sinks are more effecient but also much more costly. In most DIY applications they are over kill as well as Fans. On comercial fixtures they are crammng a lot ogf LED's in small area often only 1 inch apart so then they need to use every trick in the book to get enough cooling.

 

[TropTrea]

Am planning to use it something like this. Will this be okay ? Also, how thick should be the aluminum channel.

Thickness is not an issue other than for structural strenght. For cooling the big factor is the surface area of the material. If you have a 1/2 inch space between these rails you should be okay. But I'd like to see the dimensions so I can give you an idea of your minimum spacing between LED's on this material.

 

[TropTrea]

Thank you Dennis and Ceasar.

What do you think of a " H " channel.. the horizontal section of the channel is 1 inch and the vertical legs 2 inch... will this be a reasonable choice.

This gives you roughly just under 6 square inches of surface area per inch of lenght. You want at least 16 square inches of surface area per LED with 24 square inches being ideal. With that in mind the ideal is a 4" spread between LED's but if need by you can go as close as 2 3/4 inches between LED's. At 4" you will not need fans. but under 4" you may want to consider either fans or running the LE'd at under a 1,000 ma. Note the 2 3/4" spacing would be safe at 700 ma.

 

[SWF]

Hi Dennis, Ceasar,

Thank you so much for your inputs.

I actually managed to get hands on some heatsinks... 1.5 inch x .5 Inch with 5 fins.
That gives me 1.5 x 2.5 inches of surface. These are 4 feet in length.

My plan is to have 6 channels with 12 led's on each channel. Each channel is 48 inches in lenght.

The tank is 48 inches long with 2 inches euro braces on the ends and a 2 inch brace in the center. The 2 braces at the end will reduce the lighting area by 4 inches length wise. That will give me 44 inches of open space on the surface of the tank lenght wise.

With the above details following are my questiosn :
1) Is it advisable to cut the heatsinks to 44 inches since the reduction lenght will reduce the total weight.
2) What would be the ideal spacing between two LEDS.
3) Is it possible to mix blue and white leds.. have six blue and six white on a single channel driven by a single driver... the LED's I am going to use are XP-G R5 LEDs CW and XP-E RB.

i will be back with more questions....

Thanks again for all your help !

 

[SWF]

Hi Ceasar,

I need a favor from you.. Will it be possible for you to put together a sketch up model for me.
I tried to download your sketchup model and tried to learn a bit from sketchup training vidoes and update your model to my requeirement .. i tried but it looks like i need to practice sketch up a lot.

If you have sometime .. could you please customize your model for me ...
My tank size is 48Lx24Hx30D with 2 inch euro brach at the ends and one 2 inch brace at the center.
I am planning for 6 channels with 12 LED's on each channel.

I hope you get sometime for me .. I would really appreciate your help. I am so far only because of this thread of yours.

Thanks again for all your help all this while.

Regards,
SWF

 

[InADream]

Katchupoy,

I don't know if you are still doing the designs, but I was hoping that you could help me with my 90 gallon build. I am mainly indeed of help determining if my heats ink will work. I have a 48x18x24 tank and built my my heat sink at 44x12. I am going to use 72 LEDs. My LEDs will be spaced 2.5" apart and 4"center to center of the braces. I will have 4 braces.

Do you think this will give me good coverage. I will probably order 80 degree optics and have the light 8" of the water.

Any help you can give will be greatly appreciated.

Thanks

 

[TropTrea]

Katchupoy,

I don't know if you are still doing the designs, but I was hoping that you could help me with my 90 gallon build. I am mainly indeed of help determining if my heats ink will work. I have a 48x18x24 tank and built my my heat sink at 44x12. I am going to use 72 LEDs. My LEDs will be spaced 2.5" apart and 4"center to center of the braces. I will have 4 braces.

Do you think this will give me good coverage. I will probably order 80 degree optics and have the light 8" of the water.

Any help you can give will be greatly appreciated.

Thanks

There is not a lot of detail in your message on what your using for heat sinkks. Is it a solid piece of Alumnium plating that is 44" X 12" wich gives you roughly 1056 square inches of surface area? if so that is roughly 14.5 square inches per LED. With that in mind you do not NOT want to run your LED's up to two 2 watts. Yes they may work there for a while but eventualy will start seeing burnt out LED's.

Now if you purchased a comerciual Allumnium heat sink that is 44 X 12 you would need to look at the specs on it. Some of those will give you 5,000 square inches of cooling surface so with 70 LED's you would have over 70 square inches per LED which would be more than enough for 5 watt LED's without the need for any fans or cooling.

 

[InADream]

Sorry about that, i am using 3/4" c channel. I know that the heat sink will disperse the heat correctly I am worried about the spread of the LEDs. At the current distances will I have enough coverage to have no dark spots or shadowing. Also with the fixture 8" above the water will 80 degree optics be ok.

Thanks,

 

[TropTrea]

Hi Dennis, Ceasar,

Thank you so much for your inputs.

I actually managed to get hands on some heatsinks... 1.5 inch x .5 Inch with 5 fins.
That gives me 1.5 x 2.5 inches of surface. These are 4 feet in length.

My plan is to have 6 channels with 12 led's on each channel. Each channel is 48 inches in lenght.

The tank is 48 inches long with 2 inches euro braces on the ends and a 2 inch brace in the center. The 2 braces at the end will reduce the lighting area by 4 inches length wise. That will give me 44 inches of open space on the surface of the tank lenght wise.

With the above details following are my questiosn :
1) Is it advisable to cut the heatsinks to 44 inches since the reduction lenght will reduce the total weight.
2) What would be the ideal spacing between two LEDS.
3) Is it possible to mix blue and white leds.. have six blue and six white on a single channel driven by a single driver... the LED's I am going to use are XP-G R5 LEDs CW and XP-E RB.

i will be back with more questions....

Thanks again for all your help !

As Im picturing the heat sinks in my head you have about 8 inches of surface area per inch of lenght. Being on the safe side with 25 square inches of surface area for cooling of each LED you need a hair over 3" for your spacing I would normaly go with 3.25". With that in mind a strip of 6 LED's would take up 22.75"" inches. Your openings on the tank are long 21" on each side so with 6 LED's on each of those openings your spacing would be exactly 3" between LED's and 1 1/2" from the end of the openings.

I would leave the strips 48" long and start your LED's 3.5 inches from each end. I would then space them 3" apart which would give you roughly 24 square inches of cooling per LED. You would be leaving the bigger gap in the center of roughly 5". With the 3'5" on the end you can run an aLunium channel between the strips to hold them together and another simular on through the center.

Make sure you have 1/2 minimum spacing between your strips for air circulation, and you should not need a fan for cooling. I'm not sure how wide your tank is and if you have 2" Eurobracing on the Width as well. But your fixture with 6 rails of LED';s would have to be at least 11.5" wide. If your openings are more than 14.5" you can simply put more spacing between the Rails.

When mixing types OF LED's on a singly driver chain you need to watch there rated voltage. In the case of mixong Cree XP-E Royal Blues and Any of the XP-G whites the voltage at the sme current is close enough not to give you an issue. I actualy have several runs of 2 XP-G Neutral Whites, 6 XP-E Blues, and 4 XP-E Royal Blues.

On a personlal color taste note I do not like running all Royal Blues but mixing them with Blues so the tank not take on that blue purple tint. I also prefer using Neutral Whites over Cool Whites because they are brighter and you can use a higer ratio of blues to the number of Whites to a get simular overall look. I run roughly 3 or 4 Blues to 1 neutral White. But if I was using Cool whites I'd use more of a 1 to 2 Blue to 1 Cool white ratio. Remember this is personal taste and everyones eye preference is different.

 

[katchupoy]

im not worried about coverage, what im worried about is penetration. I rather go with narrower optics.. in my case, i spread all my light too much that i cannot even put low light corals anywhere.... I should have made them closer so that i have areas left right and center of low lights, and concentrate the lights in two areas where i can put light loving corals... tough....

 

[InADream]

So your saying that if I want to keep lower light corals, I need to use 60 degree optics. I just want to have the tank fully lit, with no dark spots. Will I be able to keep the tank lit and have lower light corals with 60 degree optics...

Thanks.

 

[katchupoy]

no its the opposite. Why narrower? Because you have deeper tank. You want to penetrated that depth. The drawback is with the same number of leds, you are sacrificing the area covered by these lights because hour optics are narrower. You may have low intensity areas in the middle of your tank and sides.

but sometimes this is good, so that in these same areas, you can put your less light demanding corals.

hope this makes sense.

 

[katchupoy]

Hi Dennis, Ceasar,

Thank you so much for your inputs.

I actually managed to get hands on some heatsinks... 1.5 inch x .5 Inch with 5 fins.
That gives me 1.5 x 2.5 inches of surface. These are 4 feet in length.

My plan is to have 6 channels with 12 led's on each channel. Each channel is 48 inches in lenght.

The tank is 48 inches long with 2 inches euro braces on the ends and a 2 inch brace in the center. The 2 braces at the end will reduce the lighting area by 4 inches length wise. That will give me 44 inches of open space on the surface of the tank lenght wise.

With the above details following are my questiosn :
1) Is it advisable to cut the heatsinks to 44 inches since the reduction lenght will reduce the total weight.
2) What would be the ideal spacing between two LEDS.
3) Is it possible to mix blue and white leds.. have six blue and six white on a single channel driven by a single driver... the LED's I am going to use are XP-G R5 LEDs CW and XP-E RB.

i will be back with more questions....

Thanks again for all your help !

1) don't cut the heatsink, weight you will loose is negligible. You need as much surface as you can to diffuse heat.
2) you have a better heatsink than mine so you can go closer. Guessing 2.5 inches? Just compute the remaining open area of your tank minus the eurobrace? Like dennis said.
3) check the spec sheet, check how high amp you can run them, and choose the lower one to be safe. Ie. Blue run on 800 while white can run 1000 then run your set at 800.

cesar

 

[TropTrea]

1) don't cut the heatsink, weight you will loose is negligible. You need as much surface as you can to diffuse heat.
2) you have a better heatsink than mine so you can go closer. Guessing 2.5 inches? Just compute the remaining open area of your tank minus the eurobrace? Like dennis said.
3) check the spec sheet, check how high amp you can run them, and choose the lower one to be safe. Ie. Blue run on 800 while white can run 1000 then run your set at 800.

cesar

Actualy with the new ratings on CREE XP-E you can run both the blues and whites at 1,000ma. Cree's new max rating are.

Whites, Royal Blues, Blues, and Greens max 1,000ma
Red Orange and Red max 700 ma
Amber max 500 ma.

For the XP-G's they are rated at max of 1,500 Watts @ 3.25 volts for actualy
4.875 Watts.

By mixing Royal Blues and XP-G Whites you have a fairly close match. at 1,000ma.

The blues running at 3.5 Volts = 3.5 Watts.
and the whites running at 3.15 Volts = 3.15 Watts

So you are safe running these two colors together at 1 Amp. It is the Reds that need to have the lower current now as the ambers that are close to 1 Watt max. But we usualy do not use Red and Amber LED's.

 

[Snausy]

So much to absorb, so confused as to what I'm going to do. Actually doing it seems to be the easy part.

Figuring out what you are going to do is the hard part. How many led, cree or bridgelux, what to use for heatsinks, rows or clusters, where to put the different colors.

Literally making my head spin. I've asked in a couple other threads...some advice would help.

300g 31" deep 8ft long...what would you do? I'm literally at the point of just trusting one of you guys that has done it a few times and seems knowlegable to tell me what to do. I really don't want to spend 700 bucks or whatever and find out that I could've done it much better for less.

Last I "decided" I was leaning towards two 120 led kits from aquastyle but they are bridgelux. http://www.aquastyleonline.com/products/120--LEDs--DIY-Dimmable-Kit.html

If I can have fewer crees to provide the same amount of light maybe that would be better. BAH! so undecided and ignorant really that I'm frozen from making a call one way or the other. SO my little 4ft T-5 fixture continues to sit there doing a crappy job.

I asked the same question in a different thread so if you answer me there I will see it, no need to post again. I'm just trying to get this figured out so I can get started! THanks

 

[katchupoy]

So much to absorb, so confused as to what I'm going to do. Actually doing it seems to be the easy part.

Figuring out what you are going to do is the hard part. How many led, cree or bridgelux, what to use for heatsinks, rows or clusters, where to put the different colors.

Literally making my head spin. I've asked in a couple other threads...some advice would help.

300g 31" deep 8ft long...what would you do? I'm literally at the point of just trusting one of you guys that has done it a few times and seems knowlegable to tell me what to do. I really don't want to spend 700 bucks or whatever and find out that I could've done it much better for less.

Last I "decided" I was leaning towards two 120 led kits from aquastyle but they are bridgelux. http://www.aquastyleonline.com/products/120--LEDs--DIY-Dimmable-Kit.html

If I can have fewer crees to provide the same amount of light maybe that would be better. BAH! so undecided and ignorant really that I'm frozen from making a call one way or the other. SO my little 4ft T-5 fixture continues to sit there doing a crappy job.

I asked the same question in a different thread so if you answer me there I will see it, no need to post again. I'm just trying to get this figured out so I can get started! THanks

Fewer LEDs? Have you looked at this???
http://www.reefcentral.com/forums/showthread.php?t=2128756

With that depth of a tank... Make sure that you will use optics for those CREEs. But like you said, figuring out some stuff is pure up to you. Let us know what you decided and we will start from there.

 

[Snausy]

Ok wow I just totally changed direction with that link. I want a few of those chips rather than 300+ 3w stars for sure! In fact why would anyone use all single 3 watters when you can use a couple/few multi-led chips instead?

Those chips look WAY brighter and really just the ticket I need for my big tank.

Thanks for the link katchupoy. Not that I know what I'm doing now but at least I have hope!

 

[TropTrea]

Ok wow I just totally changed direction with that link. I want a few of those chips rather than 300+ 3w stars for sure! In fact why would anyone use all single 3 watters when you can use a couple/few multi-led chips instead?

Those chips look WAY brighter and really just the ticket I need for my big tank.

Thanks for the link katchupoy. Not that I know what I'm doing now but at least I have hope!

That thread to me is going to the extrem with some people using 50 Watt LED's. Keep in mind that what they are using are basicly multichip packages that actualy are using 3 to 5 watt LED's. I looked into it price wise and found you are paying a premium for the Cree M series (multi chips). Then look at a package of 9 3 Watt LED's jamed into a 27 Watt package or 12 5 Watt LED's into a 60 watt package. You do have to realy worry about the correct cooling. Next you do get more more Lumns out of a 50 watt package but it is not by any means proportionate to the Lumns per watt you get with the smaller packages.

With your tank 8' Long and 31" tall I would look around the area of 450 watts of LED's. They do make some nice M series with 4 LED's rated at 10 watts and 20 watts. I would rather go with the 10 Watt units where you have less of a heating issue. with the ten watters going with 12 neutral whites and 36 Blues, or 16 Cool Whites and 32 Blues.

But it would not surprise my if your total build cost would be higher than running 144 3 watt led's and you would get more light with the 3 watt led's spread out.

 

[S2minute]

Leds

Leds

04/29/2012, 09:58 PM #1051
katchupoy
Registered Member

" im not worried about coverage, what im worried about is penetration. "

......:beer:...:celeb1:....:wavehand: