COB LED lights

sheckylovejoy said:

Newbie to indoors here (outdoor grower for several years). I am trying to pick out lights for a new indoor setup. We're putting it into a 7x7 shed outside with a 4x6 tray and 8 plants in 3 gallon pots. I plan to keep the plants under 5' (feel free to tell me any of this sucks).

It seems like people really like the new COB lights and I'm willing to make some upfront investment in something that will improve yields and keep energy use and heat down. But I'm seeing a very wide variety of prices and setups.

Questions:
1. What should my total wattage be for this setup?
2. Any brands of COB lights or kits you like in particular?
3. Is the CREE CXA3590 is the best choice for the COB? I see a lot also based around the CXB3070

Thanks

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sheckylovejoy said:

I was looking at the Timber kits, they seem like a pretty good deal for someone like me who want the CREE COBs and doesn't relish the full DIY experience. I'm a little concerned about passive cooling, so I may pop a fan in there blowing onto the heat sinks.

What do you think my total wattage should be for the 4x6 tray?

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sheckylovejoy said:

You think 35W/sq ft is enough? The Timber guy was pitching 50/ft2. This will certainly lower the costs

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sheckylovejoy said:

Thanks. What do you think of this layout with a 1 kW setup (20x 50W CREE CRA3590) in this diagram, the plants have a 1.5’ diameter and the light cone has a 1’ diameter. 8 plants, 20 lights. Scale is 100 pixels = 1'. I see dead spots in the lower left and upper right corners but that’s it.

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@ 56.3%
(4) CXB3590 3500K CD 36V @ 1.4A (49W ea) $190
(1) HLG-185H-C1400 $65
196 dissipation W -> 85.7W heat ->
passive cooled heatsink 10284cm² -> 5.88" X 38" heatsink $72 (could split in 2 to improve uniformity/spread)
or
active cooled heatsink 3428cm² min -> 3.5"X36" heatsink (for spread) $45 +80mm fan +psu $10
(4) lenses $16
110.3 PAR W covering 6ft² = 824 PPFD
$311 = $3.07/PAR W passive cooled (great value point IMO, very efficient use of driver)
$326 = 2.96/PAR W active cooled

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slow_grow said:

Give Dan at Timber a call man. I'm a new grower and just ordered a 300W kit from him the other day, I'm shifting away from a Vipar setup. He provided tons of feedback and communicates in a way that makes it easy for a newbie like me (not inferring you are new) to understand.

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sheckylovejoy said:

Took a deep dive into @Growmau5 video series and all his references last night. Learned a ton, thanks for the link (and thanks to @Growmau5 ). According to this post, the Timber's components produce these results:



The interesting part here is that @SupraSPL says 4 CXB3590s in this config get 824 PPFD for a 6 ft² space, which means my 24 ft² space needs only 16 COBs according to these calcs, not 20 or 24. I had trouble getting a pattern for 16 that made sense for a 4x6 space. I feel like a 5x5 space at 25 ft² with plants in a 3x3 grid and the COBs in a 4x4 array makes a lot of sense, but I can't find a 5x5 tray.

Here's a pattern for 18 COBs, which will save about 10% on build and power consumption vs the 20-COB array in the last design:

View attachment 3750141

I'm a little worried about the hot spots where the center rows line up, so also this possibility with 18:

View attachment 3750143

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sheckylovejoy said:

Thanks for all the great input everyone. I already have been in touch with Dan and he has been very helpful. Maybe I will wait for the new CREE LEDs.

My plans have changed a bit since last posting. I am out of town and can't post diagrams, but I realized I wasn't taking the spread of the canopy into account. Also, I've decided on doing a ScrOG.

So now the idea is to do a 4x4 tray with a 5x5 screen. I may be able to get away with only 16 COBs with this setup, but I will post diagrams later in the week when I return.

Thanks again for all the help.

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sheckylovejoy said:

New diagram (there will be 5 plants, represented here as a single scrog mass):
View attachment 3755472

The inside of the Scrog screen is 21.78 sq ft and the calcs on 16 COBs come to 912 PPFD which is awesome. My concern is that people mostly recommend a 12" center-spacing and this layout gives me more like a 16" spacing. Should that be a concern? I have represented the COBs in the diagram as 12" cones and you can see there are lots of empty spots. Also, Dan recommends 50W/sq ft and that would be more like 20-22 COBs. So is 16 enough?

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