DIY LED and Cooling system

[BluScrnOdeth]

Currently i am in the testing phase of connecting my Cree Xp-G lights to light up my 300Gallon tank. I'm building 1 unit comprising of 12 LEDs (to cover 1/4th my tank), 2 Royal Blue 3up LEDs, 2 Royal Blue 1up LEDs, 4 6500k cool white 3up LED's and 4 6500k 1up cool white LED's. All Cree XP-G's.

My current test model contains no Bucks (yeah yeah yeah, i know, i should have them, but i'm just testing, so please put comments about that elsewhere for the time being ). I used a Roof vent (thin tin i'm assuming) and sanded the paint off but i didnt feel that was good enough at extruding the heat. I'm using arctic slver 5 for the thermal paste and temporarily using krazy glue to hold them in place (just a couple small beads). I have installed a 80mm fan and everything is being powerd by a PC power supply 12v.

The 1ups are 3v and the 3ups are 9, go figure. so its 1 1up and 1 3up in parallel then all connected in series. Currently the "heat sink" im using is a U channel aluminum bracket from Lowes.

But then it dawned on me just today and was wondering if anyone has tried this or is willing to try this while i get the funds to buy the remaining 800 bucks in equipment over the next month to finish just the lighting.

Heres the idea:
Use some aluminum hollow square tubing to run water through from the sump pump. Cools the LED's, warms the water, less energy needed for heating water.

Some of you will ask, but that will eventually cook the water. True, install a flow valve so that the water will carry some of the heat away, the fan will take care of the rest, and you can find a happy medium to keep your tank warm and reduce energy consumption.

The only thing i see a problem with is 2 things:

1. Keeping the system quiet (splashing of water exiting the tubes) unless you curve them down close to or into the water.
2. Water and electricity dont mix. So extreme caution will have to be made to protect the square tube from coming in contact with electricity. Maybe an inline fuse, breaker, or something to prevent your fish and other livestock from frying.

Just thought i'd throw this idea out there to you guys and see what kind of ideas can get stirred up. I will most likely make a little prototype of this before i finish buying all lmy LED's because i would like to do it all at once rather than have to go back through and re glue/screw the led's to a new "heat sink".

This basically follows the guidelines of water cooling your PC, but i have yet to find someone online who is doing it.

Forgot to mention that i have a 1ohm resistor inline in case any of you were wondering. I used an online calc and it said that i didnt need one because it was all 12v, but it said to be safe to put a 1ohm inline to each parallel so i did. Still gets pretty warm even whith mounted ot the aluminum U channel and thermal paste inbetween.

 

[inky]

I've been thinking about it for some time. The problem I'm having is how to make the canopy removable, without squirting water everywhere. Valves will help to shut off the water, but you can't glue the pipes in place......

 

[rwb500]

"The 1ups are 3v and the 3ups are 9, go figure. so its 1 1up and 1 3up in parallel then all connected in series."

this sounds VERY wrong. in more ways than one.

oh and you cant run saltwater through aluminum. buying large, thick plates of aluminum will not be too expensive (look on ebay or elsewhere) and will provide all of the heatsinking you need.

also 99.9% of people worry more about cooling their water than cooling their lights. transferring the heat to the water causes more problems than it solves.

 

[der_wille_zur_macht]

I would stop what you're doing and go read some of the LED threads in this forum. I see several safety (i.e. your safety and the LED's safety) issues with your current build, and there are several unknowns.

Plus, as the others have stated, there are a few critical flaws with your cooling concept - most notably, the aluminum will corrode the instant saltwater hits it, and kill your livestock. If you want to water-cool your LEDs and transfer that heat to your tank water, the only feasible way to do it is with a separate closed loop of coolant, and a proper heat exchanger (made from titanium - the only metal that WON'T corrode).

 

[inky]

Plus, as the others have stated, there are a few critical flaws with your cooling concept - most notably, the aluminum will corrode the instant saltwater hits it, and kill your livestock. If you want to water-cool your LEDs and transfer that heat to your tank water, the only feasible way to do it is with a separate closed loop of coolant, and a proper heat exchanger (made from titanium - the only metal that WON'T corrode).

I think I mis-read the OP. What I meant was running pipes through the aluminium to act as both heater for the tank and cooler for the LEDs........

 

[BluScrnOdeth]

"The 1ups are 3v and the 3ups are 9, go figure. so its 1 1up and 1 3up in parallel then all connected in series."

this sounds VERY wrong. in more ways than one.

oh and you cant run saltwater through aluminum. buying large, thick plates of aluminum will not be too expensive (look on ebay or elsewhere) and will provide all of the heatsinking you need.

also 99.9% of people worry more about cooling their water than cooling their lights. transferring the heat to the water causes more problems than it solves.

What sounds wrong about it? http://ledsupply.com/creexpg-w417.php those are the white 3up, even the Datasheet says it is 9v. http://ledsupply.com/creexpg-w139.php here are the 1up 3v whites, the Blue's are of the same values.

I completely forgot that aluminum corrode pretty fast in saltwater. perhaps a plastic coating inside would do well (like they put in rusty gastanks).


der_wille_zur_macht, your a pretty bright fella that i have followed on here in some threads several times. Would you enlighten me on what safety issues you see? I cant think of any, maybe i didnt share everything that i have done??

This is just a prototype, keep that in mind, and i have followed your LED thread about DIY bucks or something, cant remember. All electrical lines are sealed, plexi covers the bottom and its siliconed in so water vapor and salt creep cant directly enter in the system aside from what the fan brings in. Even though the LEDs are thermal pasted to the rails, they seem to get pretty warm still (not enough to burn you, but enough to be uncomfortable if held there for over a minute).

I'll see about getting some pics posted tonight after i get my Java project done.

 

[BluScrnOdeth]

Ok, here is the first image of what i have done. this was just a demo to see how bright they were for 3 seconds with a 1ohm resistor.



<img src="http://www.aquatic-refuge.com/pics/6.jpg" width="400" height="300">

here is what they look like:

<img src="http://www.aquatic-refuge.com/pics/4.jpg" width="400" height="300">

here it is running all soldered with 8 total LEDs till my other 4 show up.

<img src="http://www.aquatic-refuge.com/pics/2.jpg" width="400" height="300">

here it is all assembled aside from the plexi to check for thermal issues and found none. The aluminum U channel i was using did a great job distributing and the fan cooling it.

<img src="http://www.aquatic-refuge.com/pics/5.jpg" width="400" height="300">

Here it is sitting on my tank with some temp 2x4's i had laying around span the 24" width of my 300gallon custom built tank.

<img src="http://www.aquatic-refuge.com/pics/7.jpg" width="400" height="300">

This is how it looked with just my 50/50 T5's

<img src="http://www.aquatic-refuge.com/pics/10.jpg" width="400" height="300">

This is what it looks like with the 12 LED's

<img src="http://www.aquatic-refuge.com/pics/11.jpg" width="400" height="300">

Dropped my Wattage in more than 1/2 to 56 watts for just that section. I'm going to put another column or two of 4 LED's as it didnt quite cover the amount of area that i was hoping. But it is definitely a good start.

 

[BluScrnOdeth]

"The 1ups are 3v and the 3ups are 9, go figure. so its 1 1up and 1 3up in parallel then all connected in series."

this sounds VERY wrong. in more ways than one.

oh and you cant run saltwater through aluminum. buying large, thick plates of aluminum will not be too expensive (look on ebay or elsewhere) and will provide all of the heatsinking you need.

also 99.9% of people worry more about cooling their water than cooling their lights. transferring the heat to the water causes more problems than it solves.

Forgot to comment on the 99.9% of the people remark. I guess I'm part of the .1% that has to use a heater to keep the water warm as i am from Ohio and my room temp is never close to >78 degrees. So i'm sure that the theoretical .1% wouldnt mind finding a better, more efficient way of further reducing energy costs.

One other way i reduced my energy costs was using an algae scrubber. Many may not be a fan, dont want to risk trying it, etc, but its working for me. My levels stay constant and I just clean it once a week. It could use some brighter lights to get the algae to grow better.

 

[hllywd]

I doubt the LEDs will last long with only an aluminum roof vent as a heatsink. As for coating the inside of some tubing with plastic, how do you expect it to affect heat transfer?

 

[widmer]

I believe you have got a fun idea, as far as using water to pull heat away. But it really is going to be necessary to use a heat exchanger made out of titanium or something. I'm building my heat exchanger out of glass which is much less efficient at transferring heat, but then, I'm only cooling 5x 1-up LEDs for my little ATS system that's in the works.

Coating the aluminum with something is not a good idea. Who knows how long the coating would hold up with all the heat-cool cycles, and it is certainly going to interfere with transferring heat from the aluminum.

Also, per DWZM's advice, strongly recommend you do some more reading before making more purchases. Example: 3-ups don't make sense. They're more expensive for the same amount of light, and don't allow you to blend whites and blues as evenly. How much were the 3-up blues? Because you could be getting 1-up xpe royals from cutter for $3.50, or less if you're buying in large quantity.

 

[BluScrnOdeth]

I believe you have got a fun idea, as far as using water to pull heat away. But it really is going to be necessary to use a heat exchanger made out of titanium or something. I'm building my heat exchanger out of glass which is much less efficient at transferring heat, but then, I'm only cooling 5x 1-up LEDs for my little ATS system that's in the works.

Coating the aluminum with something is not a good idea. Who knows how long the coating would hold up with all the heat-cool cycles, and it is certainly going to interfere with transferring heat from the aluminum.

Also, per DWZM's advice, strongly recommend you do some more reading before making more purchases. Example: 3-ups don't make sense. They're more expensive for the same amount of light, and don't allow you to blend whites and blues as evenly. How much were the 3-up blues? Because you could be getting 1-up xpe royals from cutter for $3.50, or less if you're buying in large quantity.

I read a lot of the LED forums here and checked out the DIY supplie list topic but i seen no mention of cutter LED's. I must have overlooked it.

I get my LEDs from LEDSUPPLY.com, the 3ups were 19 and the 1ups were 7 something. thats why i bought the 3ups, because they were cheaper per lumen than the 1ups and they were the cheapest place i found. But now that i know of this place, i'm going to have to look up this Bin and whatever they list their stuff with.

You would think that 3ups would be cheaper because you have more on one die. but i'll have to investigate further. Thanks for the heads up. And yeah, i dont think that coating the aluminum is the best idea, but it was just an idea. I'll figure something out.

 

[widmer]

Wait, I just read "my current model contains no Bucks". While you've since mentioned that you are an LED supply shopper, I presume you mean that you're powering your LEDs directly from some sort of power supply without any voltage regulating driver. I would never do this, even for a fraction of a second. You're very likely to damage the LEDs or the power supply or both. I need to be studying beta lactams right now otherwise I'd say a few more things...Seriously though, you're going to totally burn through money unless you do more reading on some fundamentals of LEDs. Hang in there, you'll be glad you did.

 

[BluScrnOdeth]

you're powering your LEDs directly from some sort of power supply without any voltage regulating driver

This is correct. I have read about the bucks and such and from what I understand they regulate the current. From what I have also read, LED's draw different current based on how "warm" they get, the warmer the more current. My LED's are underpowered as they are with the inline resistor i have installed so i was thinking that they could handle a rise in current. After all they are running at 350mA with a max of 1500mA. At least according to the data sheet. I'm nt sure how i could damage my PC power supply. It can handle 500 watts, 28A per rail and im hardly pulling anything (maybe 9A) off the one rail.

There must be something I'm missing if you two are telling me the same thing. And with there being 5k posts in some of the major LED topics, thats going to take a long time to sift through all that data.

But i will keep reading, and reading, and reading some more. I have been reading stuff from here and other sites for the past month.

 

[widmer]

LOL, tired, totally meant to say current regulating. Your white LEDs are specd to run at up to 1500 mA, your blues only go to 1000 mA (they're actually XP-E, not XP-G).

It's not that your LEDs draw different current depending on what temperature they are, its that if you aren't regulating current and you increase the voltage by like 0.2 V, this can be the difference between running them at a nice 700 mA and frying them.

Unless you have measured exactly how much voltage is coming off of your power source, have carefully calculated which resistor you need, and are taking other appropriate steps, you're gambling a lot of money.

 

[BluScrnOdeth]

i did measure the voltage coming out. It's an older power supply (maybe within 2 years old) and my meter said 11.9 something. I watched it to see what kind of fluctuations it had because that was a concern of mine but it never made it above 12. I'll leave them running again tomorrow while i'm at work and see if the rating change any when i get home. Maybe with an actual current draw it will warm things up and cause some fluctuations. I had thought about putting a Voltage regulator on there as a failsafe, but i'm not totally sure how reliable those things are.

I noticed that DWZM mentioned something about the -12V rail on a power supply but didnt get into any specifics. Ill have to look that up tomorrow. Time to get 4hrs sleep before work.

 

[widmer]

Eek... At the very least I would strongly recommend that you put a fuse on your LEDs if you want them plugged in when you're not in the house. Others would recommend that too if they were awake right now :lol:

 

[BluScrnOdeth]

lol, alright. i guess my concern for things going wrong isnt really up there. I just ran the thing for several hours, i didnt even think to test it again. I'll just wait till i get home and let it run for a couple hrs then test it.

 

[BluScrnOdeth]

I doubt the LEDs will last long with only an aluminum roof vent as a heatsink. As for coating the inside of some tubing with plastic, how do you expect it to affect heat transfer?

Sorry i skipped right over your comment somehow. The aluminum vent didnt work. It wasnt transferring the heat like i thought that it would with it being so thin. It may have been because i couldnt get a completely flat surface, maybe i didnt have enough thermal paste, not sure, the cracks looked pretty filled up with what i couldnt smooth out. So i mounted them on U channel aluminum brackets.

As far as the coating in the tubing, even though it would be an insulator, i was thinking that if you could get enough "cooler" water flowing through there it might be enough to still cool it down because of the amount of surface area inside and hopefully the lining will be really thin.

But like others have said, its still not the best idea as of yet as the lining could wear down, maybe cracks will form, etc. Many unknowns. Maybe instead of using a rubber liner like i mentioned before, you could use epoxy (which i think is prone to crack over time) or Anodized aluminum. I havent looked into that yet, as im sure it probably does still corrode, just not nearly as fast, but could still be fast enough to harm your inhabitants.

There doesnt seem to be any clear answer as of yet, so i'll keep digging, hopefully the answer doesnt cost an arm and a leg.

 

[5ft24]

The 1ups are 3v and the 3ups are 9, go figure. so its 1 1up and 1 3up in parallel then all connected in series.

Ok, this is very wrong...
a parallel circuit will have the same VOLTAGE on each note... so an LED that requires 9v in parallel with one that requires 3V will either not run the 9v unit at all, or if you have enough voltage on the 9V unit, you will toast the 3V unit in VERY short order...
Now, if you put each string as 1 1up and 1 3up in series, then you can feed that with 12v... but if the voltage changes even the tiniest amount, you may toast the LED's... they are constant current devices, not constant voltage...
rapidled has constant current power supplies for 15-20 bucks...

 

[BluScrnOdeth]

so an LED that requires 9v in parallel with one that requires 3V will either not run the 9v unit at all, or if you have enough voltage on the 9V unit, you will toast the 3V unit in VERY short order...

I think you may be thinking of something else. 9v + 3v = 12v, same with 3v + 3v + 3v + 3v = 12v. as long as you have 12 on the rail you will be fine. In a sence with the 3ups they are 3 LEDs inline, then you are just putting another one with its own star pcb to make the 4th one for 12v. So I'm thinking you must be talking about something else.