DIY LED Bars

Hi folks,

I started this thread with the intention to share my work with you and to inspire other LED enthusiasts who want to build their own LED grow lights.

I already have a ~300W DIY LED Panel on my grow room, but it was build for a much smaller grow space and as a result it could not cover my entire grow area ( ~3'x3'x4 - actually 100x105x120cm). As the price are dropping for the chinese 10W LEDs, I decided to build two additional LED bars to cover the edges.

Because my LED Panel lacks on white LEDs, I decided to use only white LEDs on this bars, 6x10W Warm white and 4x10W Cool white, 5 pieces for each bar for a total theoretical power of 100W.



As a heatsink I re-used and old aluminium sheet with some rough Al. fins attached on the back with bolts and nuts recovered from an old LED light I have built 2 years ago.



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The divers fit perfectly on the back of the heatsink , interleaved between the fins, leaving enough space for air to flow easy for cooling. I did a test without any fan or enclosure and the temperature of the heatsink went up to ~60 degrees Celsius, to much for my preferences (if I could not touch it with my bare fingers is not allowed in my grow room).



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For a proper cooling I decided small 12V fans. I was oscillating between using 40x40x10mm fans ( 4 for each LED bar) or 80x80x20mm fans (2 for each bar) and I decide to use the 80x80mm ones, because they move more air per minute , even they are a little bit louder than the small ones.

To create a channel for air to flow through I used 80x40mm PVC Cable trays: they are very cheap, easy to work with and designed for 'electrical' use.

The fans have been installed on the back od the PVC trays, right on the middle , with 4cm space between them. In this way, each fan sucks air from it's side of the bar, which flow against the Al. sheet and fins, cooling them down.



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I was forced by time to build this bars as fast as I could so I did not have time to buy 3mm bolts and nuts so I decided to use zipties to fix the fans in place. In addition, I did not have any 12V power supply small enough to fit inside the PVC channels but I have a 12V 550W switching power supply on the grow room (powering all the fans inside) so I wired the fans to a terminal block to connect them easily to the 12V circuit.



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The PVC cable trays have been attached to the Al. sheet using also zip-ties (6 for each bar). Because this bars depends on 2 separate power supplies (220V for LEDs and 12 for fans) I installed a light controlled switch to power on the fans when light is on (to be more energy efficient). During testing the maximum temperature of the LEd bars was 43-44 degrees Celsius , which is perfect.

Unfortunately I forgot to take pictures of the assembled LED Bars and I realized this only after I installed them on the grow room, aside the LED Panel, so here are some pictures of them, placed on different angles. With both LED Bars ON and only the veg lights from the LED Panel ON, the temperature raise to ~24-25C. With the LED Panel set to 100%, the temp is 25~26C with ultrasonic humidifier turned off ( when set to 50% at maximum power it cause a temperature drop of 2 to 3 degrees Celsius, due the evaporation of the water which is an endothermic process).

looks great man!

awesome work

Inquiring minds want to know.....
What did it cost?

WOW...Just fucking WOW man!!!!!!! I am so envious of your skills I am turning green...and not a healthy envy green but a Nitrogen toxic envy green!!!!!!!

You do amazing work my friend.. you really do....as tenthirty asked though, I too am interested in the final tally on the cost of the project.

I am also curious as to how the plants will react to the extra light as well....please please please keep us informed..

tenthirty said:

Inquiring minds want to know.....
What did it cost?

Click to expand...

LEDs : $20.78 for 10pcs on Ebay (free shipping)
Drivers : $46.50 for 10pcs on Ebay (free shipping)
Fans: 2~3$/piece (at a local store ; I have found much cheaper listings on Ebay but time was not on my side.)
Cable and plugs: ~3$
Zip ties: ~1$

The Al. sheet and the PVC cable tray where already available on my 'workshop' so I can't estimate the cost for them. I used 2 fans on each bar for redundancy, as this fans are low quality and they have sleeve bearings (and they could jam when oil/grease evaporates from the bearing and dust accumulates on them).

I personally hate hot light sources and I think I could improve the bars by introducing a thermal controller which cut off the power on the drivers when temperature exceeds a certain level, but this increase the costs and requires some time for the initial calibration.

My estimation is around 75$, more or less.

I just realize, again, that I forgot to measure the real power of those bars ...

vukman said:

WOW...Just fucking WOW man!!!!!!! I am so envious of your skills I am turning green...and not a healthy envy green but a Nitrogen toxic envy green!!!!!!!

You do amazing work my friend.. you really do....as tenthirty asked though, I too am interested in the final tally on the cost of the project.

I am also curious as to how the plants will react to the extra light as well....please please please keep us informed..

Click to expand...

Thanks for your kind words ! I always try to build simple 'things', as clean and simple as I can.

The plants are extremely happy with this light, I can say this because they already throw their leaves towards the LEDs and serious growth can be observed.

What I like mostly is the softness of this light. Even it's so intense, it's bearable by the human eyes and because the LEDs have no lens on them and the walls being coated with high reflective white paint , the entire grow room is flooded with light and the leaves are illuminated from all directions. I also have some ~60 degrees reflectors for this LEDs, but I tend to believe that they are not necessary (even the light intensity is almost triple with reflectors on) and the light do not blend so well as without them (being a narrow beam).

However, this project was a 'quick fix' for this current grow and also served as 'demonstrative' project for some folks interested in low budget DIY LED lights and in the future I will use those bars in a smaller grow box for some breeding experiments (on micro scale) and I intend to build a new version of those bars using XM-L2 LED when they will be available on the market (at reasonable prices).

When the LED bars will be used for (my mad scientist) experiments, I intend to install 2 or 3 more 10W LEDs on each bar ( 2 RED and maybe 1 blue ) , for a total theoretical power of 140-160W, which is enough for my 2x3x3 grow box.

hmmmm........well now......this has me thinking.. What if the next project, instead of using all 3w chips, I use 10w chips for the "white light" and then on switches place the blues and reds.....hmmm.......

Have to see the thermal dispersion for that but I think it is very doable..MUHAHHAHAHA<<<<<<<LOL....that's my 'mad scientist' laughing..

I just measured the power consumption of the LED Bars : 64W/each. WTF ??? The LEDs are rated to 10W, 10V and 100mA and the drivers are designed to deliver 900mA. This give me 128W of soft light.

64W divided to 5 mean 12.8W for each LED. If the drivers deliver 900mA as they supposed to do, this mean the forward voltage on the LED is 14.3V ???

I must measure the voltage on each LED to see where is the difference.

However, the plants love the new lights , especially Mazar who already filled more than half of the screen and I think she will need some underskirt styling, as I could not see her main stem and branches anymore.


L.E.: I measured the forward voltage on each LED : 11.4V on warm white and 11.6V on cool white.

This mean that 3 * 11.4(V) * X(mA) + 2 * 11.6(V) * Y(mA) = 64(W) [] and if the current is truly constant at 900mA :

white warms: 3 * 11.4(V) * 0.9(mA) = 30.78W ,
cool warms: 2 * 11.6(V) * 0.9(mA) = 20.88W,

together : 51.66W, which means and efficiency of 81%, so this are not the most efficient drivers, with a power loss of 19% !

Hi Hempfield...

Do you have a way of measuring the temperatures on the heatsink itself?? If you do, I would really appreciate knowing some of the temps on it please.

Right beside the chip and maybe between them as well just to know what kind of temps are being put out across the heatsink.

I would have to use something similar as I used for my original HML and just wondering the temps and also the spacing you have between them as well....

I hope I am not asking too much...

Thank you

Actually I already measured the temps: 60 degrees Celsius without PVC tray and fans (passive cooling) and 43-44 degrees Celsius with fans running. I can even put my finger on the heatsink very close to the LEDs and is not feel any hotter.

When I ran this LEDs without drivers (using just 2 rectifier diodes connected in series with the LED and powered directly by a PC 12V power supply ) there was no need for fans, having a constant temperature of 41 degrees Celsius.

As for spacing, the LED bars are 84cm long and 10cm wide. This means that each LED has it's own area of 16.8x10cm. The distance between 2 LEDs is 16cm.

I was pressed by cold weather and did not had time to buy some Al. U profiles to add them as fins of the back of the Al. sheet, which for sure could helped a lot with heat dissipation but I think to install such profiles when this round (AK47 and Mazar) is finished.

I am very surprised that the drivers push so much voltage on the LEDs and I hope that they do not burn out to soon. Anyway, I found this kind of LEDs for less than 2$/piece on Ebay, so I might buy some to have as spares : http://www.ebay.com/itm/1pc-High-Po...-Bulb-Beads-10W-Lamp-Pure-White-/360539301574

Also, the same Ebay seller offer 10W RED LEDs for $3.99 with free shipping, and this is the cheapest high power LED I ever seen ( only 40c/W ): http://www.ebay.com/itm/1pc-High-P...ht-Bulb-Beads-10W-Lamp-Bulb-Red-/130810638751

Blue 10W LEDs are also available, for $2.69/piece : http://www.ebay.com/itm/1pc-High-Po...t-Bulb-Beads-10W-Lamp-Bulb-Blue-/140892120815

I think the LEDs become with each day a serious alternative for HID (HPS/MH).

Dude!!! i want to start building a LED panel now... must find basic information

nephrosis said:

Dude!!! i want to start building a LED panel now... must find basic information

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there are plenty here doing diy led panels and I agree it makes wanted to start a diy panel appealing for sure. If you ever get started, there are plenty here who can help you along the way from start to finish no doubt.

If you get one going don't forget to post a thread up so we can all check it out

Not to much to be said about the LED bars.They are working very well and the girls seems to love that soft light.

The temperature of the bars is 43C , with a surrounding air of 25C, which is OK.

Tow days ago I noticed some flickering on a cool white LED, caused probably by the driver : the light intensity was jumping between HIGH and MEDIUM every 5-7 seconds. This abnormal behavior was seen in just one day and I think it might be caused by an improper driver initialization (I'm a little bit stoned right know ), because the problem disappeared next day.

I should have measured the forward voltage on that LED to see is there were some variations which denote a driver problem. Maybe next time ...

i really like these bars and will probably do something similar in the future when i can get back to growing

I just ordered 10 x Cree XM-L U3 1A (max 1400 Lumen at 3000mA) , 6000K to replace the CFLs from my veg box ( 60x90x120cm).

As soon as the LEDs and the driver arrive, I will post some pics and details of the construction process.

My intention is to build 2 LED bars with passive cooling, but if the heat sinks do not provide enough cooling, two small 60x60mm fans and PVC cable tray will be added to increase cooling.

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