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 luvdemshrooms
Two inch dick..but it spins!?
Registered: 04/21/08
Posts: 33
Loc: Lost In Space
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 Home built LED conversion   1
#734369 - 06/03/14 06:52 AM (10 years, 6 months ago) |
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I build LED lights for a living and thought I'd show my latest creation using a spare hood and I had on hand and some Cree CXA3050's...
This unit is for flowering so 2700K LED's were used. Alas, the CRI is 80 as none better was to be found.
I bought the 4.9" X 26" heat sink from heatsinkusa and proceeded to mill. This is the result:
I drilled and tapped some 6-32 holes and added some .089 holes to run my wires through. A thin film of heat sink grease and some 6-32 truss head stainless screws...
No mods were made to the hood so it can be used for it's original purpose should I desire.
Using a hand built driver I'm running 1.6A through the LED's. The temperature of the LED runs between 37 - 39c with a 250cfm fan blowing. Using my crappy old light meter (lux only) showed that:
1. 600w HPS was hitting 1000 lux at 2 feet.
2. My new LED unit hits 1500.
The meter may not give accurate readings as I haven't had it checked but it was used for comparison only.
I was concerned that the tube would interfere with the light output, but when measured at the same (yet unrecorded) distance on the bench there was a roughly 10% improvement when the unit is inside the tube. I chalk that up to the reflector.
Current draw? 220 watts.
Edited by luvdemshrooms (06/03/14 08:48 AM)
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Deadkndys420
Registered: 08/28/12
Posts: 8,703
Loc: █████
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Re: Home built LED conversion [Re: luvdemshrooms]
#734371 - 06/03/14 08:01 AM (10 years, 6 months ago) |
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Nice man.
Also didnt think you posted here.
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luvdemshrooms
Two inch dick..but it spins!?
Registered: 04/21/08
Posts: 33
Loc: Lost In Space
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Re: Home built LED conversion [Re: Deadkndys420]
#734376 - 06/03/14 08:44 AM (10 years, 6 months ago) |
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Thanks.
I read more than I post which is why after 6 years I'm all the way up to 17 posts including this one.
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phychotron
Medicated
Registered: 02/17/11
Posts: 1,995
Loc: Earth (mostly) 
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Re: Home built LED conversion [Re: Deadkndys420]
#734378 - 06/03/14 09:02 AM (10 years, 6 months ago) |
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Very tight, I've been growing with LED's for awhile. I was considering making my own but didn't want to go through the hassle. Check out the current grow.
How does the area coverage compare to the 600w? The thing with LED is that you can get that intense light and buds like from a 600-1000w HPS but rarely do you get the area coverage that they have to offer. Obviously you're getting 50% more light at about one third the wattage, but the focus of the light is so narrow that you'd never come near the total yield from an HPS--LED and HID are still relatively equal in terms of grams per watt maxing at about 1g/watt.
Do you know the beam angle, and have you considered secondary optics? Lenses are suppose to help the light a lot, or with that COB style I see them with individual reflectors. Have you tested how the lights compare over a grid? Not just a spot directly under the brightest part of the LED.
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Any help given is for educational purposes only. Its your responsibility not to break any applicable laws
 Bamboo Bongs I make | Perfect Dry and Cure | Grapegod under LED
“Human beings, vegetables, or cosmic dust, we all dance to a mysterious tune intoned in the distance by an invisible player.” ~ Albert Einstein
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luvdemshrooms
Two inch dick..but it spins!?
Registered: 04/21/08
Posts: 33
Loc: Lost In Space
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Re: Home built LED conversion [Re: phychotron]
#734383 - 06/03/14 09:29 AM (10 years, 6 months ago) |
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The beam angle of the LED in the open is 115°. I don't know what the effective pattern from the reflector measures. I feel the spacing and location of the LED's on the heat sink keep the beam pattern relatively unchanged from the bare LED's. Also, the heat sink is mounted in the hood at roughly the same center-line as the HPS bulb center-line.
I couldn't give you a measurement but to the eye in my 6' X 10' area, where I have 3 of these set up and running there doesn't appear to be much difference in coverage.
I have no plans to use optics as I feel the reflector does the job and optics can reduce the overall output at the same time it's reshaping it. There's a good deal of variance in the quality of the available optics.
I enjoyed the thread/journal you linked to and posted some questions regarding your clone bucket. I've just switched from cloning in soil to cloning in a bucket and I'm never going back.
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phychotron
Medicated
Registered: 02/17/11
Posts: 1,995
Loc: Earth (mostly)
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Re: Home built LED conversion [Re: luvdemshrooms]
#734389 - 06/03/14 10:02 AM (10 years, 6 months ago) |
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So you have a total of 9 diodes in that large of space? I'd love to see a grow log from these.
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Any help given is for educational purposes only. Its your responsibility not to break any applicable laws
Bamboo Bongs I make | Perfect Dry and Cure | Grapegod under LED
“Human beings, vegetables, or cosmic dust, we all dance to a mysterious tune intoned in the distance by an invisible player.” ~ Albert Einstein
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luvdemshrooms
Two inch dick..but it spins!?
Registered: 04/21/08
Posts: 33
Loc: Lost In Space
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Re: Home built LED conversion [Re: phychotron]
#734413 - 06/03/14 10:19 AM (10 years, 6 months ago) |
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The space is that large but there's a narrow isle on two sides so I can maneuver around. I'd say they're about 2' wide. Visualize a 4' X 8' sheet of foam insulation lying on the ground, shoved into a corner, with the 3 lights centered along the length and evenly space from end to end for the actual grow area (though sometimes the younger plants just transferred from the veg room wind up in the aisles).
These are LED's Cree designed for street lights and warehouse lighting. They are amazing.
A grow log would be tough as I use the continuous grow method.
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Hawksresurrection
Registered: 12/04/08
Posts: 13,464
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Re: Home built LED conversion [Re: luvdemshrooms]
#734566 - 06/04/14 05:05 AM (10 years, 6 months ago) |
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But you could still start from the next set of plants you put in there, and let us follow the through. I'm becoming more and more interested in LED's, and like seeing this type of thing.
So the temps you were getting, which translated to about 102 F or so, was that at the canopy level, or right at the reflector. I have a number of old hood I would like to try this with and see what happens. Especially if I can get the coverage that I would be getting from my current HID setups.
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Dude she isn't as young as she use to be.
-niteowl
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luvdemshrooms
Two inch dick..but it spins!?
Registered: 04/21/08
Posts: 33
Loc: Lost In Space
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Excellent question and one I should have been more specific about.
They were measured here:
Directly on the LED itself. Cree was clever enough to add a location for thermal measurements right on the LED.
However, being an excellent question it made me curious, so...
Temp outside the long edge of the hood (away from the airflow)is 26.5C (79.7F)
Temp on the glass tube directly below a LED is 46.7C (116.06F)
Temp 3" away (eyeballed) from glass tube but still directly below the LED is 26.7C (80.06F)
You can quite literally place your hand on the tube and leave it there. I was surprised to see the tube was warmer than the actual LED. Perhaps someone with a more rounded scientific background could explain why (radiance perhaps?), however I stuck my hand into the open end of the tube (the lights have been on for 3+ hours) and indeed the LED and heat sink is cooler (by hand) than the glass tube. I attempted to place the thermocouple onto the measurement pad but the light is just too bright to see it.
I was able to see well enough to measure the temp of the heat sink right next to the LED at 36.9C (98.24F)
You can see in the following jpg that coverage is good.
The ambient temps in that room are a bit higher than normal but as you can see in the far right corner one of my exhaust tubes is hanging free. I have an additional flange showing up in a day or two which shall remedy that.
I have different LED units that I use for veg but as they are built using proprietary PCB's for product we manufacture I haven't posted them but likely will (because I love to tinker). As a matter of fact I'll make a thread although my existing pictures of those older lights were taken with a cell phone.
I am now 100% LED.
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luvdemshrooms
Two inch dick..but it spins!?
Registered: 04/21/08
Posts: 33
Loc: Lost In Space
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Re: Home built LED conversion [Re: luvdemshrooms]
#734589 - 06/04/14 08:58 AM (10 years, 6 months ago) |
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A close up of one of the LED's running at very low power.
168 dies.
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phychotron
Medicated
Registered: 02/17/11
Posts: 1,995
Loc: Earth (mostly)
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Re: Home built LED conversion [Re: luvdemshrooms]
#734621 - 06/04/14 12:35 PM (10 years, 6 months ago) |
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That is some nice coverage.
The type of heat difference between LED and HID is due to infra red light. HID is rich in IR and showers every surface the light touches with this excess radiation. The plants under those lights need it cooler in the room than where the leaf surface grows optimal in order drive the cooling/shedding of this excess radiation. LED gardens tend to need a bit warmer of temperatures since they don't need to go through the IR-heat-cool cycle. LED has the excess heat (IR and heat are somewhat synonymous) go into a block of aluminum while projecting considerably less IR for the equipment/plants to absorb. If you look at what a watt is, its Joules/second, and Joules are a measure of work/heat. SO watt for watt your looking at the same work/heat but with the LED your collecting that unwanted energy before it goes into the garden.
So as for the heat difference, I'd say its due to the density of the material it has to pass through. A gas/air is like 23L per mol whereas water, a solid is .016L per mol. a mol is just a set number of molecules (6.022 X 10^23) I'm guessing the aluminum just has more inertia to absorb the radiation than the air the light is passing through. The air itself has almost nothing to stop the light intensity--the reason you can't cool IR before it hits a surface. Consider how much hotter the heat sink would be if it was half the size. Now take that down to particles spread out as a gas... THen you look at the glass that has different densities and cooling properties. Its what you call Specific Heat--the amount of energy required to raise that objects temperature by one degree Celsius. Water has a very high one at 4.18 joules/gram, Aluminum is 0.9 joules/gram, glass is 0.84. But its also probably thinner and not as much material to heat as the Aluminum.
What I'm wondering now is if you put that same sized block of aluminum under the light and see if its hotter or colder than the attached heat sink to see if its projecting more energy as light than its dissipating as heat.
This is a very tricky subject and I'm not sure if I'm explaining it right. I feel like I know why, but whether I'm explaining it right is another.
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Any help given is for educational purposes only. Its your responsibility not to break any applicable laws
Bamboo Bongs I make | Perfect Dry and Cure | Grapegod under LED
“Human beings, vegetables, or cosmic dust, we all dance to a mysterious tune intoned in the distance by an invisible player.” ~ Albert Einstein
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luvdemshrooms
Two inch dick..but it spins!?
Registered: 04/21/08
Posts: 33
Loc: Lost In Space
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Re: Home built LED conversion [Re: phychotron]
#734632 - 06/04/14 01:53 PM (10 years, 6 months ago) |
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Thanks for the info. I'm more of a mechanical guy and my business partner is the E.E. so I've still got a lot to learn.
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