help with Heat sink

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Nuno Andrade
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Registriert: Fr, 11.12.09, 18:44

Fr, 11.12.09, 19:14

Hello,

Since i don´t understand German i don´t know if this post is in the right place.
I buy from Ledrise 2 Cree led bars "Extreme-Line Plus, Warm White, 8 CREE X-RE Q2 LEDs, 960lm".
This bars are to put in a terrarium/orchidarium.
With the bars i buy a 60cm heatsink and case http://www.ledrise.com/product_info.php ... -60cm.html , which is good because it isolate the leds from humidity.
I buy a 24v, 2.1A power suply, to feed the two led bars.
When i plug the bars for experience i saw that they become really hot.
My question is if anyone try this bars with the Smd case, because i´m afraid to glue the bars with the Artic silver and if it gets to hot i can´t resolve the problem anymore.

Best regards
Nuno
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Romiman
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Fr, 11.12.09, 21:48

This case and heat sink are looking good.
But we have to know, how much current the leds will get?

I think, more than maybe 300mA would be too much for the heatsink and that number of LEDs.
Ragnar Roeck
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Fr, 11.12.09, 23:17

And never test the LEDs without a proper heat sink, you damage them almost instantly! As mentioned, try to get a constant current source (one for each bar) for 350mA and drive your bars with them. You won't get the 960lm at 350mA IMHO, but you won't run into overheating issues, too.
Nuno Andrade
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Sa, 12.12.09, 00:09

The tech spec of the cree bar said that the current must be 600-1400 ma. and the voltage 15-30v. http://www.ledrise.com/product_info.php ... 5-30V.html

The Ledrise shop wasn´t very accurate about the information of the led bar, because they said that it comes with power suply included and it was false. http://www.ledrise.com/product_info.php ... 5-30V.html

Since i don´t understand much about this issue i supose the kit sold from Ledrise was ready to function, all i have to do was to solder the pieces.
The guy from the shop in portugal sold me this http://www.mauser.pt/catalog/product_in ... s_id=54383 and said that it will work.
I don´t understand much about ellectronics and in Portugal the information about this high power leds is very poor.

I´m affraid of the heat dissipated from the bar because in the orchidarium i have to keep the temperature low.
Is the power supply correct?
Is the heatsink/case the best choise?
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Achim H
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Sa, 12.12.09, 00:24

Romiman hat geschrieben:But we have to know, how much current the leds will get?
Die Extreme Line Q2 von Ledrise ist baugleich mit der hier im Shop erhältlichen Extreme Line Q2.
Laut Datenblatt benötigt die Leiste bei 24V Eingangsspannung ca. 0,82A. Die Leistung einer Leiste beträgt ca. 20 Watt.

Vom max. Output (960 Lumen) kann man auch auf den ungefähren Strom für jede Led schließen:

960 Lumen / 8 Leds = 120 Lumen/Led
Die Cree Q2 (warmweiß) erzeugt bei 350mA zwischen 87,4 bis 93,9 Lumen.

Umrechnung:
120 Lumen / 87,4 Lumen = ca. 1,37fach.
120 Lumen / 93,9 Lumen = ca. 1,29fach.
Laut Datenblatt (Relative Flux vs. Current) müsste der Strom durch eine Led somit bei ca. 500mA liegen.

Die verwendete Kühlschiene ist (denke ich) gar nicht für die Extreme Line gedacht, sondern für die etwas kleineren High Power SMD-Leisten (um 17 Watt). 2 Extreme Line erzeugen aber knapp 40 Watt Leistung.

mfg Achim
Nuno Andrade
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Sa, 12.12.09, 01:12

Sorry but i don´t understand German.
I try to translate the text to English and Portuguese but it was not accurate.
It´s possible that i understand that the cree bar work 24v with 500ma?

Sorry about all this questions but this systems are a bit expansive and i don´t wont to make any mistake.
Nuno Andrade
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Sa, 12.12.09, 01:23

For the two cree bars and the heatsink/case that i mention do you think that is better to change the power supply (if necessary i could change it in the store)
If so what do you advice from this: http://www.mauser.pt/catalog/index.php?cPath=23_722_723
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Achim H
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Sa, 12.12.09, 06:01

Nuno Andrade hat geschrieben:Sorry but i don´t understand German.
I translate (sorry for my bad english. I hope you understand.):
The Extreme Line Q2 you bought at Ledrise is that Extreme Line Q2 who anybody can buy here in the shop. This strip needs at a voltage of 24 volt a current of approx. 0.82 ampere. The power is around 20 watts. Two of this strips have around 40 watts.
Datasheet (PDF)

The heat sink you bought isn't manufactured for the Extreme Line else than an other strip named High Power SMD Leiste. This strip has only a power of approx. 17 watts. This and the heat sink are 60 centimeters long. If you mount two Extreme Lines Q2 on one heat sink this is going hot very fast. The power of the real strip has only 17 watts else than the power of two Extreme Lines Q2 is around 40 watts.

wfg (with friendly greeting) Achim
Nuno Andrade
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Sa, 12.12.09, 17:36

Ok,

So this means that i need to buy another heatsink.
And about the power supply that i have 24V, 2.1A.
If i get another heatsink, do i have to change the power suply?

Tank you
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Romiman
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Sa, 12.12.09, 18:24

No, the power supply will ride perfectly.
You need a bigger massive heatsink.
Like this one:
http://www.leds.de/High-Power-LEDs/High ... Lines.html
Nuno Andrade
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So, 13.12.09, 03:30

Does anibody know where i can buy a heatsink like the one for SMD leds, but with more dissipate power.
I need one with some kind of place to put a acrilic cover to isolate the led bars from humidity.
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Achim H
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So, 13.12.09, 07:22

I don`t know a shop who sells greater covered heatsinks.

But I think you can mount your heatsink in another heatsink to create one with a greater surface.

For example (SK25):
Bild
The inner width is great enough to mount your heatsink into this. Use Arctic Silver Thermal Adhesive for a good heat transport (from your heatsink to this heatsink and over it into the air).

Achim
Nuno Andrade
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So, 13.12.09, 23:27

Where can i buy a heatsink like that?
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Achim H
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So, 13.12.09, 23:47

Most of electronic shops where you can buy resistors, capacitors, transformers ... have also heatsinks. In germany this heatsink (named: SK25) is manufactured by Fischer Elektronik (directlink to the english site). I don't know what shop is where you live.

Achim
Nuno Andrade
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Fr, 18.12.09, 18:54

Here in Portugal there aren´t heatsinks in bars with 1m.
The only heatsink that i found in the best electronic shops, are with 10/15cm lenght.
There is a Fischer importer but the minimum quantity to import is 3 bars of 1m, with a irracional price.
Does anyone know where i can find the SK25 or the SK68 in 1m lenght in a web shop from germany.
I try to google but i can´t find any.

Tank you
Nuno
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Achim H
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Sa, 19.12.09, 05:44

I looked at Farnell (Portugal) but there are no heatsink in 1m length available.
I looked at Cool Tec but there are no thermal measurements and no lengths visible.
I searched at google to find other shops, distributors or else, who sells heatsinks in 1m length because i found nothing.

I think you have a great problem:
The heatsinks for Extreme Line are not a really help. You must disassemble the strips without damages to mount their on 2 of this heatsinks.

Sorry!

My "uncle" (not really my uncle. All of my family says only this to him) lives in Santo Tirso (Portugal). He comes in the mid of january 2010 to germany to visiting us. I will ask him, he has every times good ideas.

Achim
Ragnar Roeck
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Sa, 19.12.09, 12:50

Not sure, but http://pt.rs-online.com/web/ could be worth a look. Even if they might not carry the 1m length you can probably add shorter sections of the desired heat-sink together.
Nuno Andrade
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Mo, 21.12.09, 00:10

Since i have 2 led bars with 27cm, if i get 2 heatsinks with 30cm each, that´s ok.
I´m frustrated because i can´t find anything.
I read in the net that the heatsinks sold by lumitronix get to much hot, so i suppose i need a heatsink with more surface area.
i discover one case with heatsink, but i´m afraid that it´s too small for the cree bars.
the name is Profil fÇr bis zu 25 mm breite LED Streifen, z. B. mit Power-LEDs and the link is http://www.simpled.de/produkte/K08.3-LED-PROFILE.pdf.
What do you think?
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TomTTiger
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Mo, 21.12.09, 06:25

Hi :D

if you buy 2 of those Heatsinks http://www.ledrise.com/product_info.php ... 27-cm.html and put the other (the smaller one you bought) into the middle space of the bigger heatsinks, you might get an better heat dissipation. The only problem that you got is, to get rid of the cooling fins on the bottom of the small heatsink.
Maybe you find someone over there to remove the fins with a milling machine.
So you get a heatsink, that also has the acrylic cover on top of the LED stripe.
Since i don't know, if the width of the small heatsink you bought fits into the space between the bigger heatsink fins, i suggest you ask for the width before you order those.

If you are afraid that the big heatsink is not enough you might think about an active cooling with a little fan...

I wish you all the best to solve that problem

Greetings
Tom 8)
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