Aluminum Bar, etc. instead of Heatsinks ?

[drew930]

I am about to get started on my LED build. Was wondering on what people thought about using other things instead of heatsinks to mount the LEDs to ? I have seen like 1x1 aluminum bars and such . What else can you use ? Will the aluminum bars get hotter than heatsinks ? As long as you have fans still your good right ?

[masharp1126]

I'm no expert by any means, but have been reading the DIY LED threads and there are a lot of people using U channel from home depot or lowes. I think the inner measurement is like 3/4" and the outer measurement, where you'll be mounting the LED's is close to 1".

[drew930]

That seems like the stuff I'm tailing about. Maybe its not aluminum. When you mount these can you make a box then weld bars across it too ? or does the fans have to blow inside the bar also ?

[heckeng]

The deal with bar vs. heat sinks is that you don't have the surface area to dissipate the heat on bar. You can think of an aluminum bar as a heat sink because it really IS just that, it is just not a very efficient one. The more surface area on your piece of aluminum, the more heat the air will take away from the aluminum. If you don't have enough surface area, the aluminum will just get hotter and hotter and potentially allow your LEDs to cook themselves.

[xCry0x]

Heat sinks are fairly cheap, why would you skimp on one and let your expensive LEDs melt?

The fins on a heat sink give the added surface area for heat to dissipate off of. There is a vendor, heatsink usa.. I think... that sells various sized aluminum sinks for cheap.

Some people use the U channels from home depot, the problems arise when you put more LEDs on one. You could probably put a single LED on a stack of pennies for a heat sink but when you are dealing with a string of 12+ LEDs in a small area you want a heat sink with a lot of surface area, which is only attained through heat fins.

[xCry0x]

Heat sinks are fairly cheap, why would you skimp on one and let your expensive LEDs melt?

The fins on a heat sink give the added surface area for heat to dissipate off of. There is a vendor, heatsink usa.. I think... that sells various sized aluminum sinks for cheap.

Some people use the U channels from home depot, the problems arise when you put more LEDs on one. You could probably put a single LED on a stack of pennies for a heat sink but when you are dealing with a string of 12+ LEDs in a small area you want a heat sink with a lot of surface area, which is only attained through heat fins.

[rysher]

aluminum U channel, welded together.
48 LED's, 20 whites run at 700mA and 28 blues ran at 900mA
Length= 34inches
Width= 10 inches
NO FANS are used for cooling.

people who said they are hot and will burn ur LED's dont know wut they are talking about. It's always the people who havent tried it that says it cant be done.

TOTAL Spent $35 including material and labor.

http://i230.photobucket.com/albums/ee307/HellRhaY/IMAG0023.jpg

[reefernutz]

I've seen them built with the aluminum U-channel. It works just fine as a heat sink and way cheaper than a heat sink.

[Jay03GT]

I built one of my setups using flat aluminum bars that are 1.5 inches wide. Used 1" angle for the frame and the flat bars for the runners (3 of them). Ran it like that for a few weeks and temps (measured with and IR temp gun) were in the mid 90's which was probably ok. I bought a cheap 120mm fan and adjustable 12vdc power supply from Radioshack, rigged up a mount and have it running at 9vdc about 5" over the center of the fixture. Now the entire fixture stays just above room temp, around 82 or 83 out on the very ends of the fixture.

The problem I see with most "heatsinks" is that they are usually pretty small, you have to pack alot of LED's in a small space, which raises the need to disipate the heat rapidly. I would recommend using U-channel over flat stock, it is what I built my second fixture out of, but if all you can find is flat it will/can work. Just get some that is wider than the minimum.

[heckeng]

aluminum U channel, welded together.
48 LED's, 20 whites run at 700mA and 28 blues ran at 900mA
Length= 34inches
Width= 10 inches
NO FANS are used for cooling.

people who said they are hot and will burn ur LED's dont know wut they are talking about. It's always the people who havent tried it that says it cant be done.

TOTAL Spent $35 including material and labor.


The current of each LED doesn't matter, what matters is the resistance and how much of that current turns to heat which they do NOT publish so whether your LEDs run at 20 mA like standard ones, or 1000 mA like higher output ones, you won't know how much heat they will put out until you assemble it. So, what works for you might really make somebody else mad if they fry all of their LEDs because you told them it is all good.

The more surface area and air flow you have, the higher the factor of safety that you won't have wasted your money on the DIY LEDs that you only bought in the first place to save the money of buying a more expensive unit that was already tested and proven not to burn up your LEDs. This reminds me of a saying a mechanic friend of mine used to have--people never have the money to do it right the first time but they always have the money to do it right the second time!

And yes, some of us who say you should be careful doing this HAVE done it before.

[iLLwiLL]

I have some DIY heatsinks over my 180 and just recently setup another LED setup over my frag tank using a real heatsink from heatsinkusa . . . the real heatsink is now all I will ever use. they are a little more expensive upfront but were building these LED setups to be used for years and years down the road. why skimp on something that could potentially damage or shorten the life of our LED's?

~Will.

[milkman55]

I used three 36" lengths of 3/4" U channel to mount 36 LEDs on 2 1/4 spacing over a 40 gal. After they run 12 hrs, the aluminum is barely warm to the touch. The drivers get much warmer than the U channel. I bought an inexpensive rivet gun which made assembly of my heatsink a snap.

[rysher]

The current of each LED doesn't matter, what matters is the resistance and how much of that current turns to heat which they do NOT publish so whether your LEDs run at 20 mA like standard ones, or 1000 mA like higher output ones, you won't know how much heat they will put out until you assemble it. So, what works for you might really make somebody else mad if they fry all of their LEDs because you told them it is all good.

The more surface area and air flow you have, the higher the factor of safety that you won't have wasted your money on the DIY LEDs that you only bought in the first place to save the money of buying a more expensive unit that was already tested and proven not to burn up your LEDs. This reminds me of a saying a mechanic friend of mine used to have--people never have the money to do it right the first time but they always have the money to do it right the second time!

And yes, some of us who say you should be careful doing this HAVE done it before.
dya know my profession by education and by trade?
make sure you are not like the guy who survived a flood and bragged his story to Noah.

And yes, some of us who say you should be careful doing this HAVE done it before.
i dont believe you.

[heckeng]

No, I don't, do you know mine? I am an engineer as I expect you are. My experience is automotive in nature, so you are partially correct, I have not made a DIY aquarium light, but I have done DIY automotive lights.

All I am saying is that a blanket statement saying that people don't need heat sinks is not a good thing. Here is an example of a guy who DID even use a heat sink and it wasn't enough cooling for him as he could not even keep his finger on the LED plate.
http://reefcentral.com/forums/showthread.php?t=2090932&highlight=cree+vs+others
With your bracketry, you obviously know that there will be an equalization point where the heat from the LEDs equals the heat removed by natural convection in the air. At that point the aluminum will be heat soaked and the LEDs will simply continue to run at whatever temperature it settles at. This will be different for every person who does a project like this and for some it will work fine, and for others it may not. You probably know this but most people making their own fixtures on this forum do not: As the LED temp goes up, the voltage required to run the diode goes down allowing current to increase which can burn up the diode. If the particular DIY controller the person has is not a current limiting controller, it will allow the current to increase until the LED eats itself. Also, LED light output and efficiency goes down with diode temperature so if your lights are not bright enough, most people will try to turn their controller up which causes the light to run hotter and potentially produce less light and potentially eat itself. This can either be a moot point, or it can be an expensive mistake and I recommend the conservative option of a heat sink with a fan. I am glad yours worked for you and wish anybody making their own setup the best of luck, regardless of what they attach their LEDs to. :beer:

[rysher]

Here is an example of a guy who DID even use a heat sink and it wasn't enough cooling for him as he could not even keep his finger on the LED plate.
http://reefcentral.com/forums/showthread.php?t=2090932&highlight=cree+vs+others
how many led's and how big is the heatsink?
no wonder mcdonalds put "beware it's hot" on coffee's.

[drew930]

Thanks for all of the replies. The only reason I would use U channel over heatsinks was because my tank is 72" ... I wanted to run U channel across , such as Rysher's , but have more . I wanted to go with 48 LED's . Have 12 on each row.( plus T5's ). It isn't as expensive to do U channel as it is to buy multiple heatsinks. But you guys are right. If Im putting 400 for LED's in my lighting , I might as well buy some heatsinks and not risk hurting the LED's.

With that said, does anybody know if someone makes heatsinks that are roughly around 60" ? I would rather buy 4 of these than buy 8 smaller heatsinks and only use one row of the predrilled holes .

[drew930]

I meant does anyone know of any place cheaper than rapidled ? for cheaper ?

[mike_cmu04]

I have been using aluminum u channel for a year with no issues

[drew930]

heckeng.... you said

"The deal with bar vs. heat sinks is that you don't have the surface area to dissipate the heat on bar. You can think of an aluminum bar as a heat sink because it really IS just that, it is just not a very efficient one. The more surface area on your piece of aluminum, the more heat the air will take away from the aluminum. If you don't have enough surface area, the aluminum will just get hotter and hotter and potentially allow your LEDs to cook themselves. "



Whats the difference in a 1.1" x 48 rapid led heatsink VS a 1" U channel ? Do the fins on the heatsinks actually make a difference ? Surface area is the same right ? Not trying to be a PITA, but please explain. I am not a LED guru , and would love to know.

[ghellin]

HYBRID!

http://i737.photobucket.com/albums/xx12/ghellin/IMAG0915.jpg

http://i737.photobucket.com/albums/xx12/ghellin/IMAG0913.jpg

[rysher]

Thanks for all of the replies. The only reason I would use U channel over heatsinks was because my tank is 72" ... I wanted to run U channel across , such as Rysher's , but have more . I wanted to go with 48 LED's . Have 12 on each row.( plus T5's ). It isn't as expensive to do U channel as it is to buy multiple heatsinks. But you guys are right. If Im putting 400 for LED's in my lighting , I might as well buy some heatsinks and not risk hurting the LED's.

With that said, does anybody know if someone makes heatsinks that are roughly around 60" ? I would rather buy 4 of these than buy 8 smaller heatsinks and only use one row of the predrilled holes .
12 LED's spread along 72inches, you wont even feel any heat.
make sure the temp stays below 80F, if you get hotter than that then add a fan.

[drew930]

Nice fixture ! Basically exactly what I wanna do . Did all of this heatsinks cost a fortune though ?

[ghellin]

They are the 10" x 1" profile from heat sink USA, they were like $3 each plus $10 or so for S and H.

[T Diddy]

HYBRID!

http://i737.photobucket.com/albums/xx12/ghellin/IMAG0915.jpg

http://i737.photobucket.com/albums/xx12/ghellin/IMAG0913.jpg

Schweet

[genxbigboy]

12 LED's spread along 72inches, you wont even feel any heat.
make sure the temp stays below 80F, if you get hotter than that then add a fan.

Hi, is 80 degrees the standard because I have been running mine with out fans and my sinks are warm to the touch. Should I add fans?

[gpx1200]

heckeng.... you said

"The deal with bar vs. heat sinks is that you don't have the surface area to dissipate the heat on bar. You can think of an aluminum bar as a heat sink because it really IS just that, it is just not a very efficient one. The more surface area on your piece of aluminum, the more heat the air will take away from the aluminum. If you don't have enough surface area, the aluminum will just get hotter and hotter and potentially allow your LEDs to cook themselves. "



Whats the difference in a 1.1" x 48 rapid led heatsink VS a 1" U channel ? Do the fins on the heatsinks actually make a difference ? Surface area is the same right ? Not trying to be a PITA, but please explain. I am not a LED guru , and would love to know.
when they talk about surface area theyr not just talking about the surface the led's are mounted on theyr talking about the total surface over bolth sides of the heatsink that air can contact for cooling this includes bolth sides of each fin on a finned heatsink this is wear they get all the extra surface area, aluminum is used for the heatsinks becouse of how fast the heat spreads throughout the matal making every little bit of surface area valuable for cooling purposes. it's realy all about geting the most air in contact with the heatsink as posible, they way i see it if you don't have enuf surface area you just need to add more air movement. i think part of the big heatsink trend is becouse alot of peapole wanted a quiet light without fans.

[rysher]

Hi, is 80 degrees the standard because I have been running mine with out fans and my sinks are warm to the touch. Should I add fans?

look at your LED specs/ data sheets. crees are i believe at 77F for maximum light intensity, after that it drops.

[rysher]

Whats the difference in a 1.1" x 48 rapid led heatsink VS a 1" U channel ? Do the fins on the heatsinks actually make a difference ? Surface area is the same right ? Not trying to be a PITA, but please explain. I am not a LED guru , and would love to know.
surface area = all the surface of teh aluminum including the fin surface
heatsinks vs aluminum "u" channels, to have max surface area on u channels, get the same length as ur tank.

[drew930]

Okay. Next question is will it make a difference if I put 2 rows of T5's on each side of LED's ( 4 rows = (8) 36" T5's ). And have my 4 rows of 12 LEDs in the middle , or should I alternate rows , T5 then LED, T5, LED. Will this give me more coverage and ake my shimmer even all the way around ?

[rysher]

the T5's might overpower the LED and u wont get a shimmer.

[drew930]

Okay.. You think less T5's then ?

[ghellin]

What are the Dems of your tank?

[drew930]

72x24x24 ( 180 gallon ).

[ghellin]

I think the two T5s would be a nice look with the LEDs. I don't think it would over power the shimmer at all.

[Crayonbreaker]

The LEDS dont get hot enough to warrant some of the heatsinks people use I dont get it but oh well I am building mine with the bar stock

[Lanimret]

I just finished my build, 72 LED's on a 40"x15" fixture. The bars are cool to the touch except immediately around the area (like within a centimeter) of the LED itself. It's not burning hot or anything, just hot.

Keep in mind that is not inside a cabinet of any kind. I will be building a cabinet around them and I will include a ventilation fan at that point, but right now it is not actively cooled and seems fine. I work with computers and am used to much, much hotter heatsinks than these are getting.

[C Dog]

How about u channel together rather than spaced? Would this help cool more?

[drew930]

How about u channel together rather than spaced? Would this help cool more?

Good question. Will multiple U Channel welded together side by side act just like a heatsink ? Good point, if it works, it would save a lot of money !!!

[rysher]

Good question. Will multiple U Channel welded together side by side act just like a heatsink ? Good point, if it works, it would save a lot of money !!!

why weld?
if u want a a bigger width, get a 1x3 or 1x4 u channel.

[gpx1200]

if your going to have led's on each strip of u chanel i think keep them seperate so you have airflow between the strips, the more u chanel you spread them over the more surface area youll have. it's better to use 3 pcs of 1inch u chanel that 1 pcs of 3 inch becouse you get more fins with the 1 inch. i was thinking of mounting 2 or 3 pcs of 1/2inch chanel inside a peice of 3 inch to form fins like a real heatsink when conecting peices you should use thermal heatsink epoxy or greese to get the best heat transfer
i attached 5 peices of 1/2inch u channel to the top of my halide housing useing epoxy and it runs way cooler now even the glass underneith is allmost touchable after runing all day

[tkeracer619]

Sure you can use aluminum bar. You don't want a thick chunk though. As others have stated U channel is more then adequate for a lot of applications. If you start packing a ton of LEDs in a tight area you will definitely want to go with a pre made heat sink. Also don't use too much thermal adhesive! You don't need or want a lot. You want fast transfer and the thinner the adhesive the faster it will be. Gooping it on won't make it cool better.


no wonder mcdonalds put "beware it's hot" on coffee's.

"from 1982 to 1992 the company had received more than 700 reports of people burned by McDonald's coffee to varying degrees of severity"

They have a warning label on the coffee because they were serving it at 180 degrees. 180F is enough to cause 3rd degree burns within seconds. Handing someone in a car a styrofoam cup with near boiling water is irresponsible and cost them millions over the years. They have since lowered the temp of the coffee.

I fail to see how your analogy is relevant to someone using the wrong amount of heat sink material whatever it may be.

[Jeff000]

look at your LED specs/ data sheets. crees are i believe at 77F for maximum light intensity, after that it drops.

For cree's if you look at the data sheet you can run them at One hundred fifty eight degrees F directly behind the center of the star on your heatsink's base metal - not fins.
I mean you will shorten the life of the LED to 70,000 hours at that temp. I know 17 years isn't long enough for some of you, but if I make it 5 years on my LED's it will be long time to upgrade anyways, just look how far LED's have come in the last 2-3 years, in 5 years (max) you will be building the next LED fixture anyways.

I can touch my heat sink about as much as I can touch boiling water. (115f directly behind the LED, 95ish everywhere else). No fan's, I'd rather have quiet than have even more years of use past when I will use them.

[rysher]

I fail to see how your analogy is relevant to someone using the wrong amount of heat sink material whatever it may be.that's because it aint a vortech.

license to troll?

[tkeracer619]

that's because it aint a vortech.

license to troll?

That makes no sense at all. What does that have to do with scolding hot coffee?

[rysher]

That makes no sense at all. What does that have to do with scolding hot coffee?

stop trolling

[tkeracer619]

stop trolling

You must be confused. I don't troll these forums.

[drew930]

You must be confused. I don't troll these forums.

Exactly right. He doesn't at all. In fact, he has helped me on more than one occasion. Thanks for the reply tkeracer619. I appreciate all the help I can get. Rysher always has to argue with somebody lol . Your just the lucky one.

[tkeracer619]

Exactly right. He doesn't at all. In fact, he has helped me on more than one occasion. Thanks for the reply tkeracer619. I appreciate all the help I can get.

Anytime m8.