First LED Build

[grispa72]

...

Ok. Now it's all clear. While I was waiting your answers I was looking for more stuff, and I could understand almost everything.
Thank you again!

Paolo

 

[Nuclieye]

Good choice on parts and I am using similar but Bridgelux versions in higher output and only two of them.  You are going to find they are too bright for being very close to the plants.  Finding or making a good enough heat sink will be difficult and VERY important.  I CNC'd mine and right behind each light engine is a high flow muffin fan to help it along.  Works well but without the fans it overheats almost instantly.  You may want to add a thermal switch to shut it all down in case of poor air flow, otherwise expect to replace the led's. 

 

[Let's Try]

Good choice on parts and I am using similar but Bridgelux versions in higher output and only two of them.  You are going to find they are too bright for being very close to the plants.  Finding or making a good enough heat sink will be difficult and VERY important.  I CNC'd mine and right behind each light engine is a high flow muffin fan to help it along.  Works well but without the fans it overheats almost instantly.  You may want to add a thermal switch to shut it all down in case of poor air flow, otherwise expect to replace the led's. 


As per a suggestion earlier in the thread, I'll be dimming these considerably. I have done the heat sink calculations to be able to run them passively without any form of active cooling (you need 17 square inches of heatsink per dissipated heat watt vs. 6 square inches of heatsink per heat watt when using a fan) and will have my heatsinks and thermal paste in a couple days. The pieces of aluminum are pretty big.

I think I'll still use fans to cool the heatsinks but I'm happy I'll have enough passive heat transfer capability in the event that any of the fans or power supply dies. Since I'll run the COBs at 700mA each and they are 64% efficient at that current, I won't have a lot of power wasted to heat to deal with either.

 

[N8thaniel]

As per a suggestion earlier in the thread, I'll be dimming these considerably. I have done the heat sink calculations to be able to run them passively without any form of active cooling (you need 17 square inches of heatsink per dissipated heat watt vs. 6 square inches of heatsink per heat watt when using a fan) and will have my heatsinks and thermal paste in a couple days. The pieces of aluminum are pretty big.

I think I'll still use fans to cool the heatsinks but I'm happy I'll have enough passive heat transfer capability in the event that any of the fans or power supply dies. Since I'll run the COBs at 700mA each and they are 64% efficient at that current, I won't have a lot of power wasted to heat to deal with either.

 
i also have a spreadsheet for calculating heatsink dissipation lol
 
 
also you can always take 1 cob off the series and it will still work on that driver)3 cobs)

 

[Let's Try]

 
i also have a spreadsheet for calculating heatsink dissipation lol
 
 
also you can always take 1 cob off the series and it will still work on that driver)3 cobs)


Do you get these spreadsheets from RIU?

 

[N8thaniel]

Do you get these spreadsheets from RIU?

 
 
the efficiency spreadsheet i got from supraspl but ive modified it since new data
the ppfd and heatsink spreadsheet i did myself

 

[Let's Try]

Well, my heatsinks arrived today and I didn't waste any time. The installation of the COBs to the sinks was actually more difficult than expected.

I bought the heatsinks used off of eBay and they came with a number of holes already drilled in them from their past purpose. This made lining up my COBs very difficult as I didn't want the back of the COB to go overtop of any of the holes, as I presume it would be really bad for heat transfer.

In pencil is the outline of one of the COBs. You can see how it just clears the holes. Of course, this plan didn't work since I ended up breaking a number of bits and taps. Since the mounting surface was so thin, when I would drill through it, the bit would come out the other side where the cooling fins are, and inevitably be redirected and broken. I ended up just drilling a very shallow hole, tapping it, and cutting my screws down short enough so they wouldn't bottom out.

Here's a COB before thermal paste is applied:

Applying paste:

Smoothed out:

Despite the few screw-ups, I think these units still turned out okay.

More to follow.

 

[grispa72]

That's real power! And you are sure to spread hot away with that heatsink! Very good job! I'm waiting for more update!

Paolo

 

[Let's Try]

I decided in order to save space, I'd do a 3'x1' shelf and do 2 rows of plants. I bought a wire shelf and got a good chunk of work done today:

I hung the LED assemblies using some nice steel wire. This should make it fairly easy to adjust the height as required by twisting the wire more as I go:

I plan to do an ebb and flow hydro setup on the bottom and wicking pots on the upper shelf.

I used black and white panda film to cover the rack, and some nice thick gorilla tape to keep it in place:

Bottom piece in place:

Wired up the lights temporarily for a quick test:

Things are looking good. I still need to add a front door to it as well as a top. It'd be nice if I could get away with no top piece since it'll allow what little heat is generated to escape, but I think it will also let out all the humidity which is worse, so I'll probably add one and see.

 

[grispa72]

Nice setup. So you go with hydroponic too!

 

[flexy123]

Hey, nice thread!
 
I JUST happen to get me pretty much a similar light w/ 4x CREE CXB3590 36V 3500K CD bin although I got me the 1750mA Meanwell driver. I have the A version with the small internal dimmer, I am driving the lights currently estimated at 1600mA, about 80% using the dimmer.
 

 
I am a little freaked now with you guys saying this is "more than mid-day in summer on the equator".
My grow space is 4x2 (120x60cm).
 
But isn't the intensity of the lights also highly dependent on the height over canopy (mine are about 2' above plants) plus I have lenses too!
 
Now I am freaking, should I dim the lights right away?
 
What would be the PAR values for my 4x2' space? I looked at the formulas but all this is confusing although I know that my fixture right now should have about 36,000-38,000 lumens. Awesome lights.
 
Edit: I also have seedlings under those lights
 
I am growing certain things, along with Cilantro, Jalapeno and Seranos. Before, that stuff was under two cheap "300W" (aka: 120 real draw) MarsHydro LED lights.
 
Edit: Mild - cool heat sinks, ah I see those lights are passive, otherwise I'd have sad overkill Nice!

 

[Let's Try]

Hey, nice thread!
 
I JUST happen to get me pretty much a similar light w/ 4x CREE CXB3590 36V 3500K CD bin although I got me the 1750mA Meanwell driver. I have the A version with the small internal dimmer, I am driving the lights currently estimated at 1600mA, about 80% using the dimmer.
 

 
I am a little freaked now with you guys saying this is "more than mid-day in summer on the equator".
My grow space is 4x2 (120x60cm).
 
But isn't the intensity of the lights also highly dependent on the height over canopy (mine are about 2' above plants) plus I have lenses too!
 
Now I am freaking, should I dim the lights right away?
 
What would be the PAR values for my 4x2' space? I looked at the formulas but all this is confusing although I know that my fixture right now should have about 36,000-38,000 lumens. Awesome lights.
 
Edit: I also have seedlings under those lights
 
I am growing certain things, along with Cilantro, Jalapeno and Seranos. Before, that stuff was under two cheap "300W" (aka: 120 real draw) MarsHydro LED lights.
 
Edit: Mild - cool heat sinks, ah I see those lights are passive, otherwise I'd have sad overkill Nice!

Wow, very nice! Almost identical...

I'm trying to figure out proper height as well. I have a row of seedlings under mine that just popped out (reaper and scorpion) and I think they're probably good where they are for now but we'll see...

 

[flexy123]

Ok I calculated 653 PPFD for my area, using the formulas and the lumens from the CREE tool.
I guess this is "ok"?

Wow, very nice! Almost identical...

I'm trying to figure out proper height as well. I have a row of seedlings under mine that just popped out (reaper and scorpion) and I think they're probably good where they are for now but we'll see...

 

 
I am glad I got the lenses, they really make the light look "professional". Without the lenses, the light looks VERY "DIY", basically just a 90cm heatsink and the COBs mounted on it. "Ugly" would be an understatement..not that anyone cares
 
I was told distance 40cm over canopy for "vegging", but this was not for the CXB3590 but for a CXB3070 and without lenses.
I'd say when in doubt, and since peppers don't use that much light, rather further away or dimming.
 
What would be the PPFD for, say, a summer day on the equator?
 
** As for peppers in general, I know people here on this forum will laugh, but Serranos is all I can handle. I grew Jalapenos this past year which for some reason had almost NO heat at all (probably not stressed enough)...but the Serranos came out nicely hot. Once In a while I get a piece which is almost too hot to me, and I am a guy who can otherwise eat hot peppers all the time. So I wouldn't even dare touching reapers, scorpion etc., in fact the thought alone scares me
 
Edit: I also have a new batch of Jalapenos and Serranos as seedlings, they look pretty much like yours.
 
We had the same idea with the 4x CXB3590 and also started peppers about the same time... I still can't say how my plants will handle the new light since I only have it running for two days...but for now everything looks good.

 

[N8thaniel]

Hey, nice thread!
 
I JUST happen to get me pretty much a similar light w/ 4x CREE CXB3590 36V 3500K CD bin although I got me the 1750mA Meanwell driver. I have the A version with the small internal dimmer, I am driving the lights currently estimated at 1600mA, about 80% using the dimmer.
 

 
I am a little freaked now with you guys saying this is "more than mid-day in summer on the equator".
My grow space is 4x2 (120x60cm).
 
But isn't the intensity of the lights also highly dependent on the height over canopy (mine are about 2' above plants) plus I have lenses too!
 
Now I am freaking, should I dim the lights right away?
 
What would be the PAR values for my 4x2' space? I looked at the formulas but all this is confusing although I know that my fixture right now should have about 36,000-38,000 lumens. Awesome lights.
 
Edit: I also have seedlings under those lights
 
I am growing certain things, along with Cilantro, Jalapeno and Seranos. Before, that stuff was under two cheap "300W" (aka: 120 real draw) MarsHydro LED lights.
 
Edit: Mild - cool heat sinks, ah I see those lights are passive, otherwise I'd have sad overkill Nice!

 
 
what driver did you get? the 240 1750A?

 

[flexy123]

 
 
what driver did you get? the 240 1750A?

 
Yup, one of the four mouser had. I am sorta regretting it since it was €82, but then again it's good to know I could run them at 1750mA.
 
Now I am in the "bizarre" situation that I have a) not enough and b) too much light all at the same time.
 
From what I researched, the 653-700 PPFD is too much for herbs and peppers, but then it's still below the optimal 1000PFD for some other plants.
I might move the herbs and tomatoes further away in my growing area I guess.
 
By the way, your posts here, especially the one with the formula, PURE GOLD. Extremely helpful.
Did you ever happen to calculate PPFD for the old Marshydro 300W lights, just wondering?

 

[N8thaniel]

 
Yup, one of the four mouser had. I am sorta regretting it since it was €82, but then again it's good to know I could run them at 1750mA.
 
Now I am in the "bizarre" situation that I have a) not enough and b) too much light all at the same time.
 
From what I researched, the 653-700 PPFD is too much for herbs and peppers, but then it's still below the optimal 1000PFD for some other plants.
I might move the herbs and tomatoes further away in my growing area I guess.
 
By the way, your posts here, especially the one with the formula, PURE GOLD. Extremely helpful.
Did you ever happen to calculate PPFD for the old Marshydro 300W lights, just wondering?

 
 
yeah the mars hydro is shit 97 L per watt from memory QER similar to what we see from these cree cobs
 
i dunno what u mean about too little and much at the same time?
 
about ppfd/too much light- there is no such thing
 
plants use light to convert nutrient into mass(in simplified terms)
so when your ppfd is high you feed more and they grow faster(within limits) 
 
the suggested ppfd will aply to soil grows primarily and really are an idea range ie what wont stress plants out and wont leave them wanting
 
you can google up the chart but it shows that at 700ppfd photosynthesis is about 75% efficient vrs 1000 being around 80% while 500ppfd is about 60% (this is for weed) but what it tells us is that there is a point of diminishing returns 
 
 
when we talk about how much light a plant needs or ideal light intensities it refers to what is a minimum. dont forget DLI which is why marijiuana while in flower recieving only 12 housr per day need such high ppfd values
vs out beautiful plants that get 16-18 hours per day needing less
 
so anyway
 
you dont have too much  light what you might have is nutrient deficiency
 
 
btw i just bought the last 240 1750B they had to build a prototype with 4 cxb 3590s lol
 
will be selling lights in europe soon

 

[grispa72]

...
will be selling lights in europe soon

Great news, hoping the costs will fall down!

 

[N8thaniel]

Great news, hoping the costs will fall down!

 
 
should be about 600 euro for a set up like these guys have(4cxb3590 on a 250w  meanwell driver)
 
for us pepper heads i think the 150w versions with 2 cxbs3590/ 3 cxb3070 will be popular(around 300 euro)
 
all dimmable all top bin etc etc etc shipping included
 
=D

 

[Let's Try]

For those interested, here's how the lights have been doing so far:

 

[grispa72]

So both hydroponic and dirt. Any differences?