TOTW 12-3-08 DIY LED Hood for Reef Tank

[Buccaneer]

So how many LED's do you estimate for a 448G tank that hasa surface area that is 8' X 3'?

[CharlotteSteve]

If your tank is 448g than it must be about 2'-6" deep. So about as deep as my tank, therefore I wil assume the same horizontal spacing. The tricky part is the vertical spacing, you can either go with three deep or two deep. I think that two will be plenty though. I included a little sketch to give you a better idea. What are you running right now?

[Buccaneer]

This is for a new tank planned for my basement

I still have the lights from my old 330G inwall that was in my old house ( 4 X 400W MH and 4 X 96W VHO )

based on your diagram I would need 192 LED's ... as a percentage of power consumption compared to the rig I already have how much energy savings do you think would be possible ?

[CharlotteSteve]

Well if you're using ~1984w of power now, with LEDs you will be using ~538w. I think the real savings here is the fact that you won't have to buy bulbs for atleast 5 years and probably more like 8. Not sure how much you're paying for your bulbs or how often you change them, but I found it to be worthwhile. I spent 180$ every 9 months for CFL's, my project only cost 400~500$. I will have made up the difference in 2-3 years. I couldn't really tell you what the impact on my power bill is. If you use a chiller right now, you won't need that anymore. This would be a HUGE undertaking with a lot of money up front though, my guess would be around $2500 when all is said and done.

[Buccaneer]

For dollars to return would I be better off looking into T5's then ?

[CharlotteSteve]

Do you already have a retro kit for t-5's? I would just stick with your MH if theyre working. For me even with having to build a whole new lighting system, the LEDs will have paid for themselves in 2.5 years, and they last for 8, so I was convinced. I guess with a bigger tank, the amount of time to make the $ difference is too long, maybe when LEDs are more commercial the prices will go down.

[hawkchalk]

Hi Steve!

First off thanks for tackling this particular area of reefkeeping as I think many can benefit from your experience in building this lighting fixture! I have a quick question regarding the construction. It looks like you mounted the LED star boards to a "T" shaped piece and them mounted conventional heatsinks to the "T" shaped piece. Is that correct? If so, why didn't you mount them directly to the heatsinks? Also any chance I could call you at some point over the weekend to ask for some more detailed questions? Thanks for you time and for sharing your efforts!

v/r

Hawkchalk

[CharlotteSteve]

Well the original design was placed on a T shaped peice of alum. However we found that this got entirely too hot after 15 minutes of running. After doing some calculations for actual heatsink surface area needed, I found that I was only providing ~1/3 of the surface area i needed. I found the current heatsink on Ebay and cut it in half (one for each side). The stars are important though because they provide a way to transfer the heat to the heatsink while maintaining a conductive path to the leads on the LED. Don't really want to post my phone # all over the net, but if you PM me i'll give it to you for more questions.

[CharlotteSteve]

buccaneer, check these out AquariumLED.com . Might save you a little time and $.

[hawkchalk]

Since I am now inspired by Steve's design would anyone like to try to get a group purchase of LEDs to drive down some of the cost? It looks like you can save about 40% if you get over 100!

v/r

Hawkchalk

[Buccaneer]

buccaneer, check these out AquariumLED.com . Might save you a little time and $.

Thanks for the link ... wonder what Kelvin rating it is

[CharlotteSteve]

Don't really know, they look white maybe 7-10k. here's another system that I thought was interesting, not to sure about the craftsmanship though Home Page

[hawkchalk]

For those that would be interested I found a dealer that sells the Mean Well CLG-150-15C for $82.54 plus shipping. Their website is: http://www.powergatellc.com. The young lady (Maria) who was helping me can be reached at Ph: 408-588-1750
Toll Free: 866-588-1750.

v/r

Hawkchalk

[hawkchalk]

After much tribulation and a number of fried LEDs I finally was able to properly drill the heatsink (7"X9"X1.75"; 3 drill bits and 3 taps later; I think the thing was made out of tempered Titanium!! ) and self-tap the screws to get the LEDs attached. In my case I definitely needed a low speed fan to adequately cool off the heatsink which was a definite surprise given the size and number of fins of the heatsink. When I did not have a fan attached it became unpleasant to touch and then I started losing LEDs. Live and learn.... Anyway, I've hopefully attached a few images of the build and the end result. Its currently going through a burn in test right now and has been "on" for over 10 hrs and heatsink is currently just a few degrees above ambient. Thanks to Steve for letting me ask a few questions offline to help complete this project!! The first image is the LED and wiring layout on the heatsink. The second image is "First Light"; the third image shows a couple of the LEDs starting to die, I believe due to overheating. The fourth image shows the array on our ottoman and the fifth shows the rebuilt array functioning nicely!! Enjoy!!!

Hawkchalk

[CharlotteSteve]

That looks good, can't wait to see them on the tank. Still trying to figure out how you burned up the lamps, the specs say that they are good up to 150 deg celsius, but there are strong warnings about running them this hot. Not sure what the actual junction temp was at the base of the LED but i imagine it was pretty toasty considering it burned up. A side note that i think I mentioned earlier: Before plugging the driver to the LEDs you have to hook it up to a volt meter to adjust the voltage. To do this turn the current and voltage all the way down. Turn the current up just a little to allow a reading, then adjust the voltage to a little above what you need for the LEDs. After you adjust the voltage intitial DONT TOUCH IT AGAIN, I'll explain in a sec. after you plug the LEDs in to the driver, turn it on and adjust the current only until the light levels out, or you can test with a multimeter to be exact. Now some of you may be wondering why touching the voltage pot is a bad thing. The driver will run in constant current mode as long as the voltage pot is stable, as soon as the voltage pot is moved the driver kicks into constant voltage mode. This can spike currents in your LEDs and possibly blow them but will definantly make the light output fluctuate. Hope this helps.

Update on my tank: The sand bed is really taking the change in light the hardest, must be more intense lighting and the eco can't keep up. I cut back some of the lit time to try and battle the cyana bact. The corals are in heaven, they are all doing well with the excepsion of the elegant which has slowly been dying for about a year (which is sad, I've had it for 5). I atribute this to an increase in water quality? I added some stoney coral to broaden the test bed too. Still haven't figured out this dimmer situation, it's a tricky one!! I really want to mount a switch on the inside of the hood to turn the lights off when I lift the case. Should post pics this week sometime.

[tahiriqbal]

Tagging along too... very interesting

[tahiriqbal]

Hi Just few questions since I myself got little bit confused on few issues you have highlighted.
If I have 30 x 3 watts LEDs, which means 90 watts in total power consumption. I would like to light all 30 LEDs from a single 12Volt 100 watt LED power driver. What would the best way to place my LEDs? Parallel or Series? I need to know if one LED blows then what method would be the best to keep the rest of the LEDS working.

Would you shed your expert advice on these questions? I would highly regard your kind help.

I am thinking of using this LED driver to run above setup. Is this any good or you would advice otherwise?

Kind Regards
DC output voltage 12V
Output voltage error ±0.5%
Rated output current 8.3A
Output current rage 0-8.3A
Wave and noise 50mVp-p
DC output power 100W
Efficiency 80%
AC input voltage range 170~250VAC
Input current 0.85A/235V
AC impulse current Cold-start
current 1.0A/235V
Leakage current <0.5mA/240VAC
Overload protection 125%
Type Reset: auto recovery
Temperature coefficient ±0.02%(050)
Setup rise hold up time 100ms
Vibration 10500Hz,2G 10min./1cycle,Period for 60min,Each axes
Withstand voltage Input and output interval2.0KVAC,
Input and enclosure2.0KVAC,Output and enclosure500VAC
Isolation sistance Input and output interval,
Input and enclosure,Output and enclosure2000VAC/3S Working temperature and humidity -10~+60,20%90%RH Store temperature and humidity -20~+85,10%95RH Overall dimension230x71x45mm

[CharlotteSteve]

I'll start with the setup at 12V. The max LEDs you can put on one SERIES string is 3 because the Philips LEDs draw 3.6V (3.6*3=10.8). I'm afraid if you try to put 4 LEDs on there they will not have enough voltage to light (4*3.6=14.4). Not a problem to throw too much voltage at the LEDs because they are current driven devices unlike most electronics. In short the LEDs will only use as much voltage as they want to use, the driver adjust itself to have a voltage drop of 0 across the LEDs. So the Driver will put out 0-12v to satisfy the LEDs.

You want to design the system keeping an outage in mind. Basically if one LED in series goes out, the whole series string will go out. This also means that the LEDs will not be drawing any current. (I think of current like water in a pipe, if you plug up a branch the water will divert to the other branches). Same idea here, if you have 10 "branches" of 3 series LEDS in parallel and one of the 10 "branches" goes out, the current will be diverted to the other 9 remaining "branches". For simplicity let’s say that each LED draws 1A. Since there are 10 branches in parallel we will need to provide 10 amps for the system. Remember that like water, each branch draws even current. Ok so we lose a branch, this means that 10A now is being divided into 9 branches, or 1.11A each. This doesn't exceed the max current but, if you have less branches with more LEDs you can see how this could potentially be a problem(Say 3 branches of 10 series leds, one goes out, your now throwing 3A into 2 branches, 1.5A each branch. At this current you will probably burn the LED up

Ok on to your driver. There are two popular ways to power LEDs. The first being the way that I did it with a CONSTANT CURRENT driver, which provides a constant current with fluctuating voltage. It must say specifically Constant Current, just because it is rated at X amps doesn't mean that it is constantly producing X amps. The other way is to use a "dirty signal" driver, like the one you have. I call it dirty because the driver puts out a fluctuating current which is bad for LEDs. But don't throw it away yet!!! All that you will need to make this work is a "filter" if you will. I would suggest the "Buck-Puck" as the most popular "filter". You should have no problem finding them online. Basically you put these things between the LEDs and the Driver. You may need one on each branch if they don't meet your capacity. No voltage or current drop here, so pretty easy. Another thing you may notice is that the driver maxes at 8.3 Amps. They will light up with 8.3A (8.3/10=.83A per branch), just not as brightly as 10amps. This may be a good thing though, if you run more LEDs at lower current, the heat dissipation increases. The LEDs will burn cooler at lower current

Hope this helps. Keep the questions coming!!

[CharlotteSteve]

A tad off topic here: anybody ever explored UV LEDs for sterilization??? Man I better hurry and patent this stuff huh?

[tahiriqbal]

Been looking into already........ design is done.... need some test runs to see if it works.....