LEDs for lettuce and microgreens

I'm thinking of getting the drivers @Mechmike even though it's not hitting 300ma. I'm needing a cheap test run at the moment and can get better ones later

Ordered 8 of them

Now looking at the 2" heatsink. Thinking of getting 8 x 12" long pieces. Or I could order all in one piece and see what number supra comes up with each led needing

Ordered 8 x Vero 10 4000k cobs also. Only have the heat sink left to deal with

ROF42 said:

I'm thinking of getting the drivers @Mechmike even though it's not hitting 300ma. I'm needing a cheap test run at the moment and can get better ones later

Ordered 8 of them

Now looking at the 2" heatsink. Thinking of getting 8 x 12" long pieces. Or I could order all in one piece and see what number supra comes up with each led needing

Ordered 8 x Vero 10 4000k cobs also. Only have the heat sink left to deal with

Click to expand...

Are you talking about Heatsink USA? Here are the #'s. I usually use 90cm2/w for passive and 30cm2/w for active cooling to calculate my numbers, as per SupraSpl's divine guidance But that is also with higher efficiencys, as well as running smaller cobs @ >40% efficiency [educated guess]. I would used 110cm2/w if passively cooling much larger cobs like the 3070 and V29 ranging towards nominal current and above

So I usually estimate about 8 watts per each Vero run on those small 300ma drivers. This is above max, so it could be a tad lower if you want, but I like "just in case". [I believe @ 285mA they are about 7.31 watts]



The surface area of the 2.08" is 84..43 cm2.
8w * 110cm2/w = 880cm2 total area needed for 8w's passive
8w * 30cm2/w = 240cm2 for 8 watts active cooling

Total surface area [cm2] / surface area per inch of heatsink [84.43] = Total length of heatsink

Passive
880/84.43 = 10.4 inches passive [For every 8 watts]

Active
240cm2/84.43 = 2.84 inches active cooling [for every 8 watts]

Thanks for the math. I was thinking of going 12" long but didn't want to be cutting just short of what I could put two cobs on to. I doubt it'll save me much to get 11 inch heatsinks.

Running soft like that you should be able to get away with around 50cm^2 of surface area per watt passively. A 12inch piece should be adequate to cool 2 cobs or 20 watts total. They're pretty tolerant really.

If I go 6" heatsink it cuts in half price and nearly half in shipping. It'll also work better for my tests with flowers in a 1 sq ft box.

Merry Christmas

ROF42 said:

If I go 6" heatsink it cuts in half price and nearly half in shipping. It'll also work better for my tests with flowers in a 1 sq ft box.

Click to expand...

I might have to do this. I have been pondering picking up something and have been calculating in 14 and 16". Gonna see if going 4 pieces instead of 2 will help, thanks!

I'll probably put in an order tonight for the heatsink.
Probably won't get drivers until February. I'm so impatient

Ordered
8 x drivers @Mechmike posted
8 x vero 10 4k from digikey
8 x 2" heatsink profile 6" long

I wonder how well and if it'd be worthwhile to use leds in the greenhouse as supplemental light. We've been having a number of grey days and the condensation blocks out a lot of light. My tomatoes got super stretchy. Too cold to produce but was wanting a good jump on early spring.

The idea would be to get a super compact vine as possible and have it mature just as the temps got warm enough.

My leds came in today and the heat sinks shipped out today. No idea where my drivers are from China

Apparently usps doesn't know where they are either. Tracking says they accepted the package several days ago but no new updates since

Heat sinks arrived. Now waiting on drivers. Usps seems to think they're still in China somewhere.

Picked up thermal paste. Frys only had a selection of three, the best being 8.4 I think it was. Called it nanosilver or some such by antec. $15 for a tiny tube.

If I remember correctly, whole China goes crazy when the year changes, so it might take some extra days for goods to arrive at this time of the year. Good luck with the project, keep us posted!

I figured shipping before Christmas would be crazy. Though from what a shoe manufacturer sent out was saying that their mid December shipment was on hold because the L.A. port was backed up. But they were shipping in mass quantity of boots for their Kickstarter backers.

Chinese new year is February 19 this year. I should put that on my travels bucket list to visit some day.

Thanks, will do. I'll probably go put together my fluorescent light fixture and have to build a new setup to test the led lights.

Advice on screwing 1x2 together. Always predrill the holes and a 1" screw is not long enough. I broke my drill bit and split all the wood after that point. Then had it fall apart because the screws were too short

There's a big dispute with the unions at the L.A. Port, they said on the news yesterday instead of taking two days to unload a ship it's now taking nine days. The longshoremen said they have cut back the number of workers unloading.

Ah well that's an explanation for the L A port. I vaguely remembering them striking a couple years back slowing everything down. I'm eager to start this experiment.

I'm thinking of building several fiberglass 2'x4' trays. Debating in 4" or 6" tall. Then debating on flood and drain for the entire life cycle, nft, or shallow water culture like the current pvc is.

I'll likely use blueboard like I have for my rafts to keep the cups from tipping over or floating around.

Then stack these trays over each other with several feet in between.

To start with I'll test the 6 light fluorescent and the 8 leds. Possibly / probably a third tray with 4 light fluorescent. Though I'm not sure how to optimize and account for light heights. Should they all be ran the same height, I'm not sure if that is a fair comparison or not

I just built a little proof of concept for someone who wanted to grow some microgreens. Basically composed of a vero 10 on a round heatsink, driver, and lens from fast tech. It was originally supposed to be a lamp project, hence why I got the lens. However it makes a huge difference in spread. At 12" it makes a perfect 24" diameter circle and at 6inches it makes a nice 12 inch diameter circle. Still waiting on a lux meter to test the intensity though, it's a huge lens(66mm) and I'm losing some photons to reflection because my heatsink isn't solid. Just need to find my drill bits so I can tap it and give it to him for testing.

Tomatoes and herbs seem to thrive underneath bridgelux 4000k light. though I'm anxious to see if a 5000k chips would work just as well or if they would work well in combination. The extra bit of efficiency would be nice.

Let me know how that goes. Would be nice to use less power on them as seedlings and move them under increasing light as they age