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[Nexogen]

I have plenty to learn, thank you for information.

[naoki]

So do I! I looked into the thermostat you recommended, and I'm going to get it when I get a chance. It would be nicer that if there is a cheap way to completely cut-off the power once the overheating occurs (something like thermal circuit breaker), instead of going on-and-off.

Also if you have the 3-in-1 dimmer like HLG B-type you have, you can connect the thermostat to the dimmer control, too. For example, the dimmer circuit is open in the normal temp (infinite resistance, so 100% output from the CC driver), but the dimmer circuit closes when overheating. You can put a small resistor so that the dimmer will cause the driver to provide only 10% of the current.

[Nexogen]

Assuming the protection of the driver no longer works, but this only happens in extreme cases, you can make your own circuit to completely cut-off the power once the overheating occurs, or you can use Thermal Fuse.
Thermal Fuse 72 Degrees Celsius
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TF 105 Celsius Thermal Fuse
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Furnace Thermostat Adjustable Limit Switch Amazon.com: 230213 - Norge Aftermarket Furnace Thermostat Adjustable Limit Switch: Industrial & Scientific
Quadrafire Reset Snap Disc
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etc.

Anyway I use electronic Temperature Control Switch (It's quite clever) and power to driver stop, fans can continue to operate and program the switch to extend time off (0-10) minutes.
Because I grow plants only in terrarium, I have a different concept.
I use Noctua's fans NF-P14s (powerful and quiet) and largest heatsink. SSL's operating temperature is 10 degrees Celsius higher than the ambient. Frankly, temperature protection never went into operation (I checked several variants and in my case it is safer).

Yes, when overheat you can put very simply a resistor in parallel on the driver dimmer. I also use this method to the next "project". For now, drivers have used the potentiometer for dimmer located inside.

... News:
I have read what and how about plants and light; Green really is quite active but I do not give up red, using the "classic" light (of course I have "enough" light green). I try. I have to give the plants what they like.
However I want, if is possible, to disregard of certain specific terms. I'm not an agronomist, all I know is what I read because orchids. I speak of the spectrum of light needed to grow orchids in good conditions. Not all respond equally to light. The plant is a very picky customer.

And one thing I grow predominantly cattleya and that's why I said that light is insufficient (in images posted by you).

[naoki]

I came across this CXB3590 kit, which was released in 1-2 month ago:

200 WATT CREE CXB3590 (4) COB KIT + MEANWELL HLG POWER SUPPLY FREE SHIPPING - Timber Grow Lights

This is good for people who doesn't like to assemble since no assembly is required. It will be good to cover 4'x4' (or 8'x2') area for moderate light orchids.

Good components; 4x top-bin CXB3590 driven softly (50W per COB) and the best MeanWell driver. I'm not familiar with the heatsink they use. It is all pre-assembled, so you don't need to do anything. You only need to figure out how to hang them. Dimmer is included (goes down to 10%). $399 + free shipping for 200W (4x 50W). If you assemble the components by yourself, you can save $100 or so, but for people who doesn't have time to assemble or not sure how to assemble, $100 extra may be worth. They also have 5x50W version for $499. PRODUCTS - DIY GROW LIGHT KITS - Timber Grow Lights

This is pretty much the best in terms of PAR efficacy (about 2.5 micromol/J from my calculation), and most LED grow light can't touch it. The PAR efficacy is measuring how many photons relevant to plants are produced for a given amount of electricity. In comparison, Fluece (=BML) SPYDRx, released in early 2016, is one of the very best and achieves only 2.2 micomol/J. I said "only" 2.2, but it is a very high efficiency number. You should know that cheaper LED grow lights give about 1.0 micromol/J, only slightly better than T8 or T5HO. Very good HPS is around 2.0 micromol/J. In terms of lumen (not so relevant, but people are more familiar with it), it is giving about 177lm/W.

In terms of COB front, I recently learned about a better alternative to Cree. I don't need a newer grow light for me, but if you are interested in DIY route, I would definitely look into Citizen CitiLED COB Series Version 5. There are several sizes, but something around CLU048-1212C4 seems to be the sweet spot in terms of price and efficiency ($12.55 from CDI). This is a smaller COB, so you'll need 2 of CLU048-1212C4 to replace 1x CXB3590. At the moderate driving current, the efficiency is very close to CXB3590. Maybe you can drive it at 1050mA (36.8W), which gives 169lm/W @ case temperature (Tc) of 50C, or better yet at 700mA (23.7W), which gives 179lm/W (similar to CXB3590 @ 50W).

[naoki]

I just spent a bit of time to write up a blog post to help DIY LED grow light builders. The DIY COB post is one of the most frequently accessed post in my blog for some reason (even though I think other biological posts are more fun to me), so this is a follow up, and explain more fundamental principles of LEDs. In this post, I tried to explain the basics of driver selection and the design process. Here is the link to the blog post. It talks about the multiple LEDs driven by a single driver, basics of driver and LED efficiency, and super simple thermal protection. I tried to target beginners, but it might be too much information or a bit too technical. Hopefully, it is useful for some people since winter is coming (well, it's been here for a while in Alaska).

I also updated the original DIY COB blog post with newer information (i.e. there are much better/cheaper COB than Cree COB).

Here is my recently cleaned grow tent with 8x COB LEDs.


Here is a PPFD map of 4x CXB3590 with HLG-185C-1400B. It is showing amazingly even distribution of light over 120x120cm (4'x4') area in the grow tent. The unit is micromol/m^2/s.


Here is the relationship of dimming vs overall efficiency. So with this driver, using dimming function doesn't decrease the efficiency unless you dim it extremely (i.e., as long as you stay above 30% of the full power, it is explained more in the blog post).

[larrylwill]

I see your still at it, good write ups. Have you looked into red led grow lights now instead of white? They seem to be getting more and more popular. Have you calculated what it cost to run your setup tent? Have you figured out how many hours per day to run lights? and what is the best orchids to grow in it?

I am not having much luck with my florescent lights in the sw window or my garden room, I have only had 1 cat bloom 2 times and a sherry baby bloom 2 times none this year. I do have some Oncs that are not under light that bloom every year and this year my Bird of paradise has 3 blooms on it. This is the 3rd year. Its in a pot and not under light.

Im also growing 5 banana trees and trying to get some bananas. The need 18 months to grow a bunch, there also in pots, the winters here are too cold to leave outside. Although if it keeps like it is now 80 degrees tomorrow maybe I can.

[naoki]

Larry, there are efficient red monochromatic LEDs, but they cost much more than white COBs. Those cheap red ones are not as efficient (in terms of PAR) as modern white COBs. A lot of grow light makers have been migrating from blue+red based to white or white+red.

The 4'x4' grow tent has about 200W at the bottom shelf, and 160W (they are more efficient than the bottom ones, so I can dim it down) at the top shelf. So about 360W. We have high electricity cost so (360W / 1000) * 13 h/day * 365 days/year * $0.2/kWh = $333 per year.

I've been using 13h/day. I use 11h/day for temperate carnivorous plants, which need longer night to induce dormancy.

I grow almost all of the orchids under 100% artificial light in grow tents, so you can grow almost any orchids. Lower light plants are easier. Also, shorter plants are easier. My favorite is Paphiopedilum. I can grow and bloom Cattleya, but it becomes quite expensive.

I don't know well about Oncidium, but some Cattleya are photoperiodic. In other words, they prefer to have shorter nights in summer, and longer nights in winter. So some may not flower well if the yearly cycle is not accommodated from what I hear.

[larrylwill]

I haven't seen any high power Red led either.
Im sure its buried in this thread but what color temp are you using? It would be nice to show you rtent with some blooming Orchids in it.

[FairyInTheFlowers]

Saving this for future reference! Thank you for all the well written information!

[Nexogen]

Originally Posted by larrylwill

I haven't seen any high power Red led either.
Im sure its buried in this thread but what color temp are you using? It would be nice to show you rtent with some blooming Orchids in it.

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