DIY LED with COBs - small medium and large grows

[DcBig bud]

I'm thinking about building one of these for a 2 ft x 2-1/2 x 8ft closet space. The plan is to use four cxa3070 cree chips running at 50 watts. This is my only space so my thought is to use as much light as possible. Does this sound like overkill? Will four cobs give me heat problems in this little space? and last but not least, should I use a combination of warm and cool white? By the way, I should mention I plan to grow autoflower in this area. Any help would be much appreciated. Thank you.

 

[Lenny Gray]

I'm thinking about building one of these for a 2 ft x 2-1/2 x 8ft closet space. The plan is to use four cxa3070 cree chips running at 50 watts. This is my only space so my thought is to use as much light as possible. Does this sound like overkill? Will four cobs give me heat problems in this little space? and last but not least, should I use a combination of warm and cool white? By the way, I should mention I plan to grow autoflower in this area. Any help would be much appreciated. Thank you.

When you ask about the 4 x 50W COBS and heat, you may be missing the importance of airflow. (I underestimated it when I first started.) In addition to getting the heat out, you need to recycle the "air" so fresh CO2 comes in while your light's shining. As for how much heat your 2'x2' closet can handle, actually test it by pushing 200 Watts into the closet set up as you expect it to be used. You can probably borrow a couple of incandescents from someone (there are still lots of neo-Luddites around). But it's really about the (heat) energy. If energy (power) flows out of the wall, and can't escape into the world, it builds up in your grow-space. Also, for the 12-hour dark cycle, consider photo-darkroom louvers that let air in without light. Make sure you also let the air out.

 

[Greenbyme]

Hi all, I'm a french guy and I have some difficulties to understand all you said. I didn't find information on French sites so as I'm brave and even my English is poor, I'm asking for advices. I want to cover 4ft x 4ft only with COBs and if I understand I need 50w per sqft. So I must install 16 COBs! Oh sh**, I don't have enough money! My questions are: Can I do with only 9 COB? Do I prefere 3070 or 3590 for the COBs? And for the driver I don't understand "efficiency". When you want calculate how many watts are used finally, do you use this formula : P=UxI? Anyway I need your advices to grow the best French DIY! :-) Thanks in advance for your help! And very thanks to all information already given here!

 

[WitchWeedSG]

best place to find out great info is invalid.com, there are a lot of DIY active threads going on there roll it up dot org

 

[Greenbyme]

Hi! Thanks for the links!
And about lumens? You always talked in watts! I saw different COBs and drivers with different quantity of lumens. Then what's really important to think when you want plan your diy? Thanks in advance, I found nothing about that. Cheers

 

[kailiwela44]

the first page shows 4 small LED light considered a small build. I would like to replicate this to cover an area 30"Wx18"Dx36"H. I will be using this light/setup as a full spectrum used for veg and flowering.
Can someone assist me with a shopping list of the main components?
Does anyone run these on a digital timer?

 

[Lenny Gray]

There are a few truths to keep in mind about growing with LEDs. First, commercial lights generally call their fixtures by the full-power ratings of their LED parts, but only run them at 1/2 that power. Thus, a "300 Watt" LED light might run at 150 Watts of real volts-times-amps power. This is to run the LEDs in a relatively "efficient" zone. Overall efficiency is the percent of electricity that turns into light. For white light, 100 lumens-per-watt was the best you could expect until about two years ago. Now, Cree's CXB3590 DD commercial whites (though not cheap chips) give 200 lumens-per-watt when run at 1400ma, and Cree has announced that 300 lumens-per-watt is coming. The number of lumens is actually a perceived brightness unit, and non-white gives less "lumens" as its peak. Photosynthetically Active Radiation, "PAR", is probably a more appropiate number, though only rarely specified so far, and is what plants can "see" for growth. Fifty watts of volts-times-amps power is probably the limit of what can be feasibly handled in a tent, though half that is still "respectable". It is said that one gram per grow per watt of power is probably the limit of what can be expected by a moderately proficient grower.

 

[Lenny Gray]

Fifty watts of volts-times-amps power is probably the limit of what can be feasibly handled in a tent, though half that is still "respectable".

A missing phrase in the above: "Fifty watts of volts-times-amps power PER SQUARE FOOT ..."

 

[Greenbyme]

Many many thanks for all these information! :-)
Do you know when Cree plan to launch this new COB? For the moment I don't have the COB, I only begin to buy the material to build it.

 

[Toaster79]

CXB3590 is already on the market, maybe not that specific bin, but it's out there

 

[Greenbyme]

CXB3590 is already on the market, maybe not that specific bin, but it's out there

Ah it's the same series. I had understand a new model. Sorry, I often use Google translat ;-)

 

[Lenny Gray]

the first page shows 4 small LED light considered a small build. I would like to replicate this to cover an area 30"Wx18"Dx36"H. I will be using this light/setup as a full spectrum used for veg and flowering.
Can someone assist me with a shopping list of the main components?
Does anyone run these on a digital timer?

This was my first incarnation of such a puppy, as a prototype, though currently still in use in my vegging shower-stall (not very heat sensitive). The parts-list was:

One Arctic Alpine 11-GT rev 2 CPU cooler with fan (saved from a retired mobo)
though available on eBay, new, for $12
One 100W LED driver, constant current, AC 85V-265V, Output 30V-36V, from eBay
Was $16, new, on eBay from China at the time (though read below)
one 100W Warm-White LED from eBay (cheapie Chinese)
currently listed on eBay for $12.40 for 4, $4.41 for one, shipped from China
One 12v 500ma-1A Wall-Wart Power Supply (from my junk box) to run the fan
though currently listed on eBay for < $2 shipped from China

The $16 100W LED driver cost more than a more efficient and cooler-running 50 Watter that can be used with the 100W COB, currently listed on eBay for $9 shipped from China, and what I used in my second prototype.

Running at 100W is acceptably cool with this heatsink combo, though ones like the author's pictures, with the bigger fan and heatsink, run even cooler.

I used heatsink compound for contact, and regular epoxy at the corners to keep the COB in place.
It's not even hot enough to degrade the epoxy.

I have the driver epoxied to the heatsink's fan-cage.

The only thing to beware of are polarities of the fan and the COB, and running the COB for
any significant time without the fan running. And yes, I run it, with other things, on a timer.

 

[treeharvest]

First of all I have to add this is one informative thread I must say. So much that I decided to join and ask some questions. I have been wanting to change my grow setup since July. I am currently using a 4x4 tent for flowering and a 2x4 homemade tent for vegging which is in 2 different closets. My plan is to move everything into one closet. Giving me about a 11.5 Sqft for flowering thats 6.5 ft tall and a 6.5sqft area thats about 6ft tall for veg. However I plan to lower the veg area to 3.5 in order to have a small space to clone above it. I'm also thinking of maybe doing 7.5 of flowering space and have an extra 4sqft for mothers. I have not decided yet.

Currently I am running 3 kessil 350's magenta's for flowering and 2 kessil 150's blue for veg. I plan to retire those LED's and use them for actual vegetables like greens, sprouts, and micro greens. They get the job done now but my buds are always pretty small. But this is for self medication so I dont need to win any awards or relay on these for income. I just want to setup this new closet where I am able to harvest 2 to 3 small 2-3ft tall plants every 2-3 months with out having to use much power to achieve.

I am pretty much a newb when it comes to electrical stuff. However I have changed out all the lighting fixtures in my house and have built t5 lighting fixtures in the past for growing. I have also built my own air scrubbers using bathroom exhaust fans. So I have a little bit of experience in electrical DYI, but I pretty much glaze over when I see watts, volts, amps, etc. The way I look at it, I basically have 6 weeks to learn. I currently have 4 plants in veg and I plan to make all mothers and clone from them this week. So my guess is that I wont have any new plants for flower until 6 weeks or more.

From what I gathered I believe a need 7 to 8 COB's (CXB3590/CXA3070) for flowering. Does that sound right for 11.5 sqft? As for Veg im confused, what led should I use and how many? Would it be easier to just keep using my current 150 kessil's for vegging since it seems like in veg you don't need as much light? Unless I understood that wrong from the previous posts. I would like to keep the cost under around $800 if possible, but i can go over if needed. Given that this is for personal use though i would like to keep the cost down as much as possible.

Thanks for the help!

 

[kailiwela44]

This was my first incarnation of such a puppy, as a prototype, though currently still in use in my vegging shower-stall (not very heat sensitive). The parts-list was:

One Arctic Alpine 11-GT rev 2 CPU cooler with fan (saved from a retired mobo)
though available on eBay, new, for $12
One 100W LED driver, constant current, AC 85V-265V, Output 30V-36V, from eBay
Was $16, new, on eBay from China at the time (though read below)
one 100W Warm-White LED from eBay (cheapie Chinese)
currently listed on eBay for $12.40 for 4, $4.41 for one, shipped from China
One 12v 500ma-1A Wall-Wart Power Supply (from my junk box) to run the fan
though currently listed on eBay for < $2 shipped from China

The $16 100W LED driver cost more than a more efficient and cooler-running 50 Watter that can be used with the 100W COB, currently listed on eBay for $9 shipped from China, and what I used in my second prototype.

Running at 100W is acceptably cool with this heatsink combo, though ones like the author's pictures, with the bigger fan and heatsink, run even cooler.View attachment 548646

I used heatsink compound for contact, and regular epoxy at the corners to keep the COB in place.
It's not even hot enough to degrade the epoxy.

I have the driver epoxied to the heatsink's fan-cage.

The only thing to beware of are polarities of the fan and the COB, and running the COB for
any significant time without the fan running. And yes, I run it, with other things, on a timer.

So if I were to use a 100watt driver that would be enough to run two crew 3070 cobs wired in series? Would that make the two crees run at 50watts each?

I'm now trying to figure out and understand the math. How to power my area with 3 or 4 crees 3070 running a total of 100 watts.

 

[Toaster79]

3070 has Vf of 36V nominal, check datasheets for exact numbers at certain currents.

P=U*I

 

[Lenny Gray]

So if I were to use a 100watt driver that would be enough to run two crew 3070 cobs wired in series? Would that make the two crees run at 50watts each?

I'm now trying to figure out and understand the math. How to power my area with 3 or 4 crees 3070 running a total of 100 watts.

Actually, no. Most of the math is not about solving equations, but scanning datasheets and noticing the endpoints. Those cheapie constant-current supplies I mentioned are limited in the voltage they can source -- in the case of the one I mentioned, 36 volts, so it's just a single 36v COB supply that runs one at 100W. As I mentioned, if you wanted to run, say, some Cree's at 50 watts each, getting 50 watt drivers is best (yes, they're 100W COBs that'd then run at 50W each), and, in fact, probably cheaper. You want to notice the current that a driver wants to source, and its maximum voltage. There are some 72-80v drivers around that you could do the series trick for a pair, and maybe higher voltage ones for 3 or 4 but you'd want it to be like 1400ma as the current to run each 36v COB at 50W. There are 900ma drivers around, too, for separately running each 36v COB at about 32W which is a good efficiency zone for the COB. For $7.20 apiece, runs at 88% efficiency for the driver.

 

[klx]

Hi @SupraSPL

First off, thanks for all your efforts across all the forums.

Before I go headlong into replacing 2k watts of HPS with LEDs I figured I would start out slowly and cheaply and replace the clone area's CFLs while I am still getting my head around it all.

Could you confirm this config would be good for 60 clones:

From earlier in the thread:

3 x https://www.fasttech.com/products/1...e-xp-l-v5-2a-1186-05lm-5700-6000k-led-emitter

3 x https://www.fasttech.com/products/1506/10001927/1163600

Run in series at 300 mA using the following driver:

https://www.fasttech.com/products/0...1w-85-277v-3w-high-power-constant-current-led

Cheers!

 

[Lenny Gray]

Hi @SupraSPL

First off, thanks for all your efforts across all the forums.

Before I go headlong into replacing 2k watts of HPS with LEDs I figured I would start out slowly and cheaply and replace the clone area's CFLs while I am still getting my head around it all.

Could you confirm this config would be good for 60 clones:

From earlier in the thread:

3 x https://www.fasttech.com/products/1...e-xp-l-v5-2a-1186-05lm-5700-6000k-led-emitter

3 x https://www.fasttech.com/products/1506/10001927/1163600

Run in series at 300 mA using the following driver:

https://www.fasttech.com/products/0...1w-85-277v-3w-high-power-constant-current-led

Cheers!

3 Watts, total, seems way low, even for LEDs, even just for clones.

 

[klx]

It is based on this so I think will be ok and save me 37 watts of electric right there.

When it comes to cloning we are not looking for photosynthesis, just trying to keep the plant in the vegetative state and we do not want it to respirate too much until the roots are established. At 300mA, the XML2 and XPL can reach above 180 lm/W and will last a lifetime with zero lumen depreciation and almost no electricity consumption (~1.6W). So I clone with 1W in a 12"X18" space and have for a few years now. It works great even with large clones. I also use this method for my headlamps to make them lightweight and batteries last an entire day of use.

 

[WitchWeedSG]

showing some stuff i learned to make from these fine gentlemen..almost got the big mother done
6 cxa2530 's and 48 XML2's HLG-185H-C700B on Cob's and HLG-185H-C1400B for the xml's
blasting 174 watts on the cobs without the fans running, heatsink was probed with multimeter temp
after 5 minutes reached 88f..almost done fans are in, waiting on chips from slowtech
WwW