DIY LED light for 3 ft tank

[thebaldingaquarist]

Hi all,
Seen forum-ers DIY their LED light switch. I decided to DIY one for my 3ft as well.

This DIY project will serve 2 purposes. To replace my 3ft light set and to serve as a preparatory course for my DIY LED light switch for a 5 or 6 footer tank for my new place.

I am into planted tanks and i want to use CREE 3W white emitters for this project.

After viewing through Dealextreme, i have made an inventory list to get.

1. 2 Aluminum housing, 90 cm long each. Corners filed down and smooth. looks like the pic below only that its aluminum
http://lh3.ggpht.com/_LYre0qeo_ec/TL.../nEO_IMG_3.jpg
2. 20 3W emitters.
http://dx.com/p/cree-xr-e-r2-wg-emit...s=1920&u=15943
3. Optics for the emitters
http://dx.com/p/23-36mm-optics-light...s=15943&u=1920
4. LED driver
http://dx.com/p/1-7a-60w-power-const...v-47305?item=1

inwares LED, if you mind me using your pic, please let me know. I will ask mod to remove my post.

Plan is to have 2 light sets made with the aluminum housing, joined using screws.
Each housing will have 10 3W emitters.

The driver's output will be split into 2 (parallel) into each of the housing. Thereby making it
1.7/2 Amperes
30 to 36 Volt

I have some questions,
1. Anyone knows where i can get such housing and have the shop owner help me drill holes? I will do the necessary calculations to spread the emitters evenly.
2. Do i need a resistor?

Any comments on the setup?

Thanks all.

[32103940]

Hi, I hope you havent ordered your parts yet, because there are some very serious issues with this setup.

1) XR-E is rated 3W at 350mA(~100lm) and Max is 3.7W at 1000mA (~240lm). The driver you listed at 1700mA will destroy all 10 LEDs.
2) XR-E is not worth the money. A spiral CFL can beat the lumen output at same wattage, cost less, have better CRI etc..., even the R2 grade of XR-E you chose is the best of the XR-E, but still,
people DIYing LEDs will go for XM-L which will give almost double the output per watt. more expensive, but as mentioned, LEDs are worse than fluorescents (for planted tank) unless you get recent technology.
3) Don't take the rated wattage of an LED for granted. Find the spec sheet from the manufacturer (CREE) to make sure you know what voltage drops to expect by running the LED at a certain current.
e.g, a 3W CREE XM-L is only 3W when run at 700mA (~80lm), and measures 2.7V. But it is specified able to run at 3000mA which makes it 10W at 3.3V (900+ lm). If you are not careful, either the wattage or total required voltage can exceed your driver's rating, in which case you wont be running your string of LED's as you intended.

Your case, for example, assuming you found a 1000mA driver, 10 XR-E will require 37V, which exceeds the driver rating. Typically you should leave an additional 3+V tolerance. Meaning a 1000mA driver with 36V max output should be loaded with 8 LEDs only. 30W MINIMUM capacity.

But still, I recommend XM-L.

[thebaldingaquarist]

Hi, I hope you havent ordered your parts yet, because there are some very serious issues with this setup.

1) XR-E is rated 3W at 350mA(~100lm) and Max is 3.7W at 1000mA (~240lm). The driver you listed at 1700mA will destroy all 10 LEDs.
2) XR-E is not worth the money. A spiral CFL can beat the lumen output at same wattage, cost less, have better CRI etc..., even the R2 grade of XR-E you chose is the best of the XR-E, but still,
people DIYing LEDs will go for XM-L which will give almost double the output per watt. more expensive, but as mentioned, LEDs are worse than fluorescents (for planted tank) unless you get recent technology.
3) Don't take the rated wattage of an LED for granted. Find the spec sheet from the manufacturer (CREE) to make sure you know what voltage drops to expect by running the LED at a certain current.
e.g, a 3W CREE XM-L is only 3W when run at 700mA (~80lm), and measures 2.7V. But it is specified able to run at 3000mA which makes it 10W at 3.3V (900+ lm). If you are not careful, either the wattage or total required voltage can exceed your driver's rating, in which case you wont be running your string of LED's as you intended.

Your case, for example, assuming you found a 1000mA driver, 10 XR-E will require 37V, which exceeds the driver rating. Typically you should leave an additional 3+V tolerance. Meaning a 1000mA driver with 36V max output should be loaded with 8 LEDs only. 30W MINIMUM capacity.

But still, I recommend XM-L.

Many thanks for your advice. I will note them.

I have not ordered the parts yet. By XM-L do you mean
http://dx.com/p/xmlawt-1000-lumen-le...v-51989?item=7
?
Thanks again.

[32103940]

yes...and T6 means it's the second grade of XM-L. lower grade is T5 and highest grade is U2. take note that for the T6, it states 1000lm but that is for 3000mA and it will use approx 10W. on the U2 page, its 320lm at 700mA (<3W). at the end of the day both can be run from 700 to 3000mA. U2 will get you about 5+% more lumens. may not be worth the extra S$2 per piece, but it's up to you. remember that all the lifetime guarantee is based on 700mA testing, but typically people will run 2000-3000mA which will make a ton of difference to brightness degradation etc. so it can be a good idea to buy more lower LEDs and drive at low current than lesser LEDs at full current......just some extra thing to note. who knows, in 1 or 2 years there might be new LED tech and you will replace anyway.

[dc88]

Hi 32103940
This is very informative data and insight ! Thanks for sharing.

Reading this I am getting tempting to modify my current lighting fixture.
One question I would like to seek your advice is the XML if output at 1000lm just by a single LED cell would it be too concentrate to a single bright spot ? How to distribute the light out ?

[thebaldingaquarist]

yes...and T6 means it's the second grade of XM-L. lower grade is T5 and highest grade is U2. take note that for the T6, it states 1000lm but that is for 3000mA and it will use approx 10W. on the U2 page, its 320lm at 700mA (<3W). at the end of the day both can be run from 700 to 3000mA. U2 will get you about 5+% more lumens. may not be worth the extra S$2 per piece, but it's up to you. remember that all the lifetime guarantee is based on 700mA testing, but typically people will run 2000-3000mA which will make a ton of difference to brightness degradation etc. so it can be a good idea to buy more lower LEDs and drive at low current than lesser LEDs at full current......just some extra thing to note. who knows, in 1 or 2 years there might be new LED tech and you will replace anyway.

Fantastic advice.
I will probably get the XML T6 and drive it at 1000mA.
Any recommendations for drivers if i want to drive 2X series of 10 LEDs each?

[32103940]

1000 lm is not a lot really. Something like 11-13W CFL. Gotta take note if you want to grow plants or you just want a decorative light for a nano tank. The difference is that for LED, all that light is coming out of a small area, which means only the small spot under the LED gets full intensity while everywhere else it drops noticeably. Can counter this by raising the LED but 10W is not a lot to be raising up so high.

Also because the light is a point source you are going to get crazy shimmer. some people like it. I think it's quite distracting...my ceiling looks like indoor swimming pool ceiling. Lol.

about the driver, don't have any to recommend. Dealextreme is pretty good price wise and the more popular drivers have a lot of customer reviews.

[Shadow]

Do take note on PAR, LED do have produce more PAR than CFL, T5 and PL.

[dc88]

how much wpg is enough for LED if consider the higher PAR ?
say if my current setup of CPL is 3 wpg (67 lumen/liter) if switch to LED how many watt needed to give same level of PAR ?

[Shadow]

not a clue, you need PAR meter to measure that . PAR measurement take into account the light spectrum that being used by plant for photosynthesis. Same wattage may generate different PAR depending on the brand. What you can do is look around at different website, some one out there might have same setup and did the PAR measurement

[thebaldingaquarist]

After taking advice and making my own guesses and reading, my inventory list is now
1. 2 Aluminum housing, 90 cm long each. Corners filed down and smooth. looks like the pic below only that its aluminum
http://lh3.ggpht.com/_LYre0qeo_ec/TL.../nEO_IMG_3.jpg
2. 20 emitters.
http://dx.com/p/xm-lt6-885lm-led-emitter-6000k-white-light-bulb-3-0-3-5v-50599?item=1
3. Optics for the emitters
http://dx.com/p/23-36mm-optics-light...s=15943&u=1920
4. LED driver
http://dx.com/p/2a-70w-power-constant-current-source-led-driver-85-265v-54004?item=1

Setup is the same, 2 series connected in parallel to the Driver. Each series has 10 emitters.

Any comments?

By the way, anyone knows where i can get the aluminum (with help drilling and filing)?

[32103940]

looked throught the spec sheet for you. at 1.7A, voltage drop is ~3.12V per unit. 10 LED means about 31V and 53W. Driver looks good for the setup. estimated ~6200lm. a T5HO 54W is about 5000+. i doubt LED will give better PAR watt for watt but i won't be surprised if it is close. still, because of higher luminous efficacy, one rail of this setup may likely give you better PAR than 54W of T5, and will produce less heat. as for the heatsink, any piece of metal big enough to space out 20 LEDs properly over a 3ft tank is big enough to dissipate your heat.

[acidjc]

IMHO, your should get the LED with color temp 1000K. The light spectrum is better for plant

[benkho]

u mean 10000K? 1000K is very very very warm. most people have been using 6500K or so LEDs.

[Shadow]

Setup is the same, 2 series connected in parallel to the Driver. Each series has 10 emitters.

Any comments?

You should avoid connecting high power LED in parallel. Just imagine what will happen if one out of 10 LEDs in series burn and open circuit, or soldering problem or contact corrosion. You might end up burn the other series of 10.

[Shadow]

Interesting article comparing LED and MH light from http://www.americanaquariumproducts...._Lighting.html


Legend
*Dark Blue = LED Lights (6500K)
*Light Blue = Necessary PAR Spectrum of Chlorophyll
*Lavender = Metal Halide (6500K).

Interesting to see that 12W LED can grow better plant than 175W MH, not sure how true but after seeing the spectrum it make sense. Although MH is brighter, but the spectrum does not match the photosynthesis spectrum.

So be carefull when using LED, you want to grow plant not invite algae

[thebaldingaquarist]

looked throught the spec sheet for you. at 1.7A, voltage drop is ~3.12V per unit. 10 LED means about 31V and 53W. Driver looks good for the setup. estimated ~6200lm. a T5HO 54W is about 5000+. i doubt LED will give better PAR watt for watt but i won't be surprised if it is close. still, because of higher luminous efficacy, one rail of this setup may likely give you better PAR than 54W of T5, and will produce less heat. as for the heatsink, any piece of metal big enough to space out 20 LEDs properly over a 3ft tank is big enough to dissipate your heat.

I was also trying to get my colleague to help look at the data sheet! thanks alot for the effort. Point noted on the heat sink.

IMHO, your should get the LED with color temp 1000K. The light spectrum is better for plant

u mean 10000K? 1000K is very very very warm. most people have been using 6500K or so LEDs.

Noted on the temperature. Will give this LED a go and update on the results in a separate thread.

You should avoid connecting high power LED in parallel. Just imagine what will happen if one out of 10 LEDs in series burn and open circuit, or soldering problem or contact corrosion. You might end up burn the other series of 10.

Noted on the good advice! Usually we should not go for parrallels when connecting diodes (unless we are using a don't know what device as advised by my colleague). But in my case, i am using this as a learning opportunity.

Thanks for all the advice. Now on the aluminum hunting...

[32103940]

oh i thought you were going to use 2 drivers, one driver for each string of 10 LED...because 1 driver cannot run 2x10 series LED. basically each LED will only get 850mA.

[dc88]

not a clue, you need PAR meter to measure that . PAR measurement take into account the light spectrum that being used by plant for photosynthesis. Same wattage may generate different PAR depending on the brand. What you can do is look around at different website, some one out there might have same setup and did the PAR measurement

So it will be a while until enough people trying out LED and publish their results so to compile a new "wpg" reference (or any other new way of rating). The current watt-per-gallon reference was a good internet community effort over many years and across many sites, and with benchmark to experts' tanks setup such as Amano, Tom, Diana,...etc.

Erctheanda
Thanks for sharing your venturing into this new area. Pls sharing the results, you have all our support.
Last but not least pls do take care of safety such as grounding, heat ventilation, etc.

[Shadow]

I'm not sure about Diana, but Amano never mention wpg (not that I can recall) and Tom hate wpg

wpg really does not tell you anything. Furthermore, wpg does not work in small tank, big tank nor odd shape tank .