Build Your Own LED Grow Light

[Mayne]

People keep touting one COB or lightstrip over others, so I prepared comparison tables for the color temp and CRIs of interest to me. The tables will help in selecting what I'll use for my lights, and the drivers required.

Manufacturer	Part No.	Efficiacy	Current	Voltage	Watts	lm @ 50W	Cost
BridgeLux Gen6	BXRC-30E10K0-L-2x	137lm/W	2100mA	38V	79.8	6850	Obsolete
BridgeLux Gen7	BXRC-30E10K0-D-7X	146lm/W	2100mA	36.6V	76.8	7300	$31.89
CREE CXB3590	CXB3590-0000-000R0HCD30H	179lm/W	2050mA	36V	73.8	8950	$58.15
Citizen	CLU048-1216C4-30*M2M2-F1	149lm/w	1440mA	34V	49	7450	$13.65
Samsung	LT-FB22B	168lm/W	1120mA	46V	51.5	8400	$26.51

Table 1: Comparison of 3000K 80CRI LED Sources​

Manufacturer	Part No.	Efficiacy	Current	Voltage	Watts	lm @ 50W	Cost
BridgeLux Gen6	BXRC-30G10K0-L-2x	114lm/W	2100mA	38V	79.8	5700	Obsolete
BridgeLux Gen7	BXRC-30G10K0-D-7X	123lm/W	2100mA	36.6V	76.8	6150	$31.89
CREE CXB3590	CXB3590-0000-000R0UBD30H	149lm/W	2050mA	36V	73.8	7450	$48.60
Citizen	CLU048-1216C4-30*H5M3-F1	128lm/W	1440mA	34V	49	6400	$13.65
Samsung	LT-M562H (3 req for 50W)	117lm/W	700mA	24	16.8	5850	Obsolete

Table 2: Comparison of 3000K 90CRI LED Sources​

OK! I heard that! Yes I know, Lumens and Lux for people, PAR and PPFD for plants. So then, why did I include Lumen data in the tables? It's simple really. Manufacturers rate their lamps that way, and there is a method of determining PAR and PPFD from their spectrums which are also published by manufacturers. It's a long process involving picking relative intensities from images and plugging the values into an equation. That's next on the agenda for a couple of the lamps.

It seems reasonable that PAR and PPFD will track with Lumens and Lux. If you can accept that, then we can use the data above to select lamps for further investigation. It's readily apparent that the CREE CXB3590s outperform all contenders in efficiacy measurements. Perhaps a better measurement would be power required for a standard of illumination. At 5000lm this is 27.9watts for the CREE CRI 80, and 33.5 watts for the Citizen. This translates to an extra 5.6 watts of heat per COB that may have to be removed from the grow space if the Citizen were chosen.

Next we might want to compare the cost of ownership for the COBs, including initial cost and electrical cost over their lifetimes.

CO = Initial cost + (life expectancy in hours * power used / 1000) * cost/kwh
CO = $13.65 + (50,000 * 33.5 / 1000) * 0.15 = $264.90 (Citizen at 15¢/kwh)
CO = $58.15 + (50,000 * 27.9 / 1000) * 0.15 = $267.40 (CREE at 15¢/kwh)

As you can see, at 15¢/kwh they pretty much cost the same. Just for giggles, at 25¢/kwh let's see what happens:
CO = Initial cost + (life expectancy in hours * power used / 1000) * cost/kwh
CO = $13.65 + (50,000 * 33.5 / 1000) * 0.25 = $432.4 (Citizen at 25¢/kwh)
CO = $58.15 + (50,000 * 27.9 / 1000) * 0.25 = $406.90 (CREE at 25¢/kwh)

Surprisingly there is not much difference. It would take two to three years before the CREE pulls ahead of the Citizen at the higher power cost.

There's more I need to check. First there's those PAR and PPFD conversions. Then we have the drivers, heatsinks, mounts, and other parts needed to make a useful grow light out of the COBs.

Hold your horses! Relax, and have a little of your product. I'll get there, hopefully sooner rather than later.

man, wish Luminus cxm22's were in that list.

 

[Old Salt]

man, wish Luminus cxm22's were in that list.

There's nothing stopping anyone from adding, or posting the information.

I did look it up and have just asked the moderators to add it to the post. Hopefully it will show up in the next day or so.

 

[Old Salt]

...I figured that with cannabis now emerging as a legit commercial reality there may be specific science on PAR as it relates to cannabis...

When and if someone decides to do the research, I think many folks will be surprised. I strongly suspect that different strains, and even phenotypes will grow better with differing spectra. My reasoning for this is the different coloration of the leaves. They range from a light green to dark green, and purples. To me that indicates differing spectral absorptions.

 

[Mayne]

right on, How about microscopic video of different light spectrum and the way they interact with it.

 

[Mayne]

There's nothing stopping anyone from adding, or posting the information.

I did look it up and have just asked the moderators to add it to the post. Hopefully it will show up in the next day or so.

Cool OldSalt, I could of added them, but I didnt know your formula, and NEI, But love your efforts man, very helpful for this thread. Thanks,

 

[tobler]

When and if someone decides to do the research, I think many folks will be surprised. I strongly suspect that different strains, and even phenotypes will grow better with differing spectra. My reasoning for this is the different coloration of the leaves. They range from a light green to dark green, and purples. To me that indicates differing spectral absorptions.

Absolutely agree.
So many variables with spectra and phenotypes which can't be considered without the context of temperature, humidity, medium, feeding, timeing ect.
All said and done a "controlled" "efficient" grow is part science and part art.

 

[Mayne]

Im doing a COB build. Still researching, kinda.

4 Luminus cxm22,s with a 480H-C2100B

For a 2x2

Tryin to decide on the 80 or 90 CRI. What difference does it make>!!?? lol..

Looking to order this week, and get this done.

So, what I take from everything, is,

I can run these at the highest 1800ma at 55volts, or 99 watts each MAX, And can dim down to 60 watts to use at least 50% of the driver.

am I correct on that thinking?

 

[Old Salt]

Here's the data on the Luminus devices. The 80CRI is first. You'll note that they come in last of the ones on the list.

Manufacturer	Part No.	Efficiacy	Current	Voltage	Watts	lm @ 50W	Cost
Luminus XNova	CXM-22-30-80-36-AC00-F2-3	133lm/W	1280mA	35V	45	6667	$15.01
Luminus XNova	CXM-22-30-90-36-AC00-F2-3	113lm/W	1280mA	35V	45	5667	$15.01

As to CRI, there is indication that the 90s are better in some situations. They apparently have a coating that changes their spectrum, and reduces the emitted light somewhat. You'll need to check the grow journals here to find some side by side comparisons. Be aware that there is no 'perfect light' for personal growers. We grow different strains under the same light. A commercial grower can get it very close for the rooms with a single strain by using adjustable spectrum lighting.

I've been spending about 10hrs / day for the last two weeks researching and planning my light design. I'm not pulling the trigger until I have the data in for the light sources I chose for further investigation. Hopefully I'll finish by the end of the week.

 

[Mayne]

awesome man, in same boat. Definitely know Im going COBs, thats for sure, then, its like, hummmmmm, I just heard Luminus cxm22 were the best route to go.

so, i began to base my build on that.

and thats again, with the thinking, Lower price range, but yet, very decent output.

 

[PurpleGunRack]

Here's the instructions I found for computing PPFD if you have the spectral power distribution of a light source:



Since we can get the spectral power distribution of the COBs and light strips, all we need to do is pick off the data, decipher the above, and perform the calculations. Easier said than done.

I'm still plugging away at it. But first a little

I think there are way to many variables to do this accurately, and there is no mentioning of how far away from the surface the light is, or how much space it has to cover.

The only way of really knowing the PPFD in ones grow space is to get a proper PAR meter and measure it, and they don't come cheap, the cheap ones are sometimes more than 10% off...

Im doing a COB build. Still researching, kinda.

4 Luminus cxm22,s with a 480H-C2100B

For a 2x2

Tryin to decide on the 80 or 90 CRI. What difference does it make>!!?? lol..

Looking to order this week, and get this done.

So, what I take from everything, is,

I can run these at the highest 1800ma at 55volts, or 99 watts each MAX, And can dim down to 60 watts to use at least 50% of the driver.

am I correct on that thinking?

I would say that it's overkill, the COB is 37,5v max, so running the driver on max would overpower the COBs.

Check out page 6 for info on the COB https://www.mouser.com/ds/2/245/Luminus_XnovaCXM22_Datasheet-522672.pdf

 

[Mayne]

the data sheet im seeing is 54volts, 110 watt max,

8,530 lmn at 1100ma, and max is 2400ma,

So, i get HLG-480H-C2100B, then the COB cant be overdriven, but the Driver will only allow it to run as high of 99watts, due to volt distribution.

probably wrong, lol, but thats what I put together

 

[Mayne]

OOoohhh, I see, Im getting Gen3, those are the first gen i guess,

here is the data sheet https://cobkits.com/wp-content/uploads/2016/12/Luminus_XnovaCXM22-GEN3_Datasheet.pdf
Luminus CXM22 Gen3 3000K 80 CRI – CobKits.com

 

[PurpleGunRack]

OOoohhh, I see, Im getting Gen3, those are the first gen i guess,

here is the data sheet https://cobkits.com/wp-content/uploads/2016/12/Luminus_XnovaCXM22-GEN3_Datasheet.pdf
Luminus CXM22 Gen3 3000K 80 CRI – CobKits.com

Yeah, you're right it's not third gen

Gen 3 is 55v max, and 2200 mA max, so that driver is still able to overpower them.
If you put in 2,1 amps and 55v into one COB you're pulling 115,5w per COB, and at the minimum voltage of 48v they run at 100w each, either is running them way too hard in my opinion.

It's best to run COBs under 50w each

 

[Mayne]

ok, so 320H-C1400C is the winner for this idea?

 

[Old Salt]

I think there are way to many variables to do this accurately, and there is no mentioning of how far away from the surface the light is, or how much space it has to cover.

The purpose of my R&D is not to provide an accurate model at this time. It is to allow me to make an apples to apples comparison of various light sources.

The Photosynthetically active radiation (PAR), Lumen, and Radiant Flux conversion Calculator will give you values dependent on height. This calculator is based on McCree's 1972 research, The Action Spectrum, Absorbtance and Quantum Yield of Photosynthesis in Crop Plants. McCree did his measurements at 25nm intervals, which is too coarse for my liking. I'm re-plotting his results so that I can interpolate the results to 5nm. It should be more accurate, at least enough to provide an apples to apples comparison of light sources. Another problem with the calculator is that it uses a black body temperature for it's input. I'm changing that to allow data entry for various light sources. I refer to them as light sources, as I'll also be able to evaluate commercial grow lights.

The only way of really knowing the PPFD in ones grow space is to get a proper PAR meter and measure it, and they don't come cheap, the cheap ones are sometimes more than 10% off...

Agreed. You can use a sensor costing about $200 and a voltmeter to get readings. This setup is probably more accurate than the lower cost models.

 

[Mayne]

Well, welcome back, but I wont be here to much, I cant stand the new boards, annoying to read.

 

[PurpleGunRack]

ok, so 320H-C1400C is the winner for this idea?

It would work, but then you would put 320w into the 4 COB's.

Personally I would get a HLG-185-700 or a HLG-240-700 for a total of 200w and 250w respectively

 

[Old Salt]

It would work, but then you would put 320w into the 4 COB's.

Personally I would get a HLG-185-700 or a HLG-240-700 for a total of 200w and 250w respectively

For my first drivers, I'll select 'B' model oversized constant current drivers. I'll be able to set the current for the light output I want, and measure it. Then, when I know what to expect, I'll order properly sized drivers for my next build.

Frame building Tip: Use Alumiweld rods and a propane or MAP gas torch to get a professional result. Amazon carries the Alumiweld.

 

[Mayne]

I ended up going with 2x 185H-C1400B ( 74watts each COB max ) 296 all

just deciding on the K value.

4x 3500-90cri

or

2x 4000-80cri
2x 3500-90cri

 

[Mayne]

that 4000K helps build thick, strong stems.