D.i.y. Cxb-3590 Cob Panel Vs. Hps

[jdb420]

I did some COMSOL simulations on this a couple weeks ago. I'll have to go back and see if I can find those files at work. I may not have saved them, but I can do it again if I have time.

Yes, please let us know the difference in temperature between the two. I know the larger one will run cooler, but how much cooler is what I am interested in. Do you use thermal paste or pads ? If thermal paste, what brand ? I'm curious to see if there is anything that you like better than the artic silver 5 I am using. Thanks for all the information ! And just for the record, timber and northern both have excellent customer service. The items were padded extra well to avoid damage during shipping. Both of them were happy to answer any and all of my questions. So, just know that both of these companies are legit and shipping time was 7 to 10 days. I like to buy from American companies if I can. I used Jerry at kingbrite for a lot of my items I bought. He has been great, but I would like to order from American companies any time I can. I'll get some photos going soon, and let you know what I think about performance. I got larger heatsinks for the two lights bars I am rebuilding. The other 4 kits I got from timbergrowlights.com. I will let you know the temperature difference between the two in the next few weeks.

 

[HughJassBud]

Yes, please let us know the difference in temperature between the two. I know the larger one will run cooler, but how much cooler is what I am interested in. Do you use thermal paste or pads ? If thermal paste, what brand ? I'm curious to see if there is anything that you like better than the artic silver 5 I am using. Thanks for all the information ! And just for the record, timber and northern both have excellent customer service. The items were padded extra well to avoid damage during shipping. Both of them were happy to answer any and all of my questions. So, just know that both of these companies are legit and shipping time was 7 to 10 days. I like to buy from American companies if I can. I used Jerry at kingbrite for a lot of my items I bought. He has been great, but I would like to order from American companies any time I can. I'll get some photos going soon, and let you know what I think about performance. I got larger heatsinks for the two lights bars I am rebuilding. The other 4 kits I got from timbergrowlights.com. I will let you know the temperature difference between the two in the next few weeks.

I'll get together a list of all the stuff I'm using. I can't remember the name of the paste off the top of my head. I've read reviews and test that show it is roughly as good as artic silver and I can buy it in a much larger tube. The tape works really well too. I saw a paper on this recently that was very well written, I will try to look for it if I can. The results were interesting because if you looked at the conductive efficiency or thermal resistance of the tape vs paste with temperature, the lines would cross on the graph at some point. As I recall, the tape was better at "lower" heats while the paste ultimately out performed it at "higher" heats. The heatsinks they were using for the test were polished and surfaced appropriately as well as run without any prep. The tape out performed paste when no prep was done. However, they had some pretty wonky heat sinks with some doming.

I will try to get around to running those simulation here soon. I have been doing a lot of this lately and probably not enough work. I have some research deadlines on the 11th so I may have to focus on that for a few days, but I will definitely try to get some COMSOL time in when I can. It is just a simulation though and only as accurate as the parameters I program into it. I think it is a pretty good ballpark, but I definitely wouldn't put too much faith in my results. I would consider the results more qualitative than quantitative, if that makes sense. There are others that are far better at this than me that could provide much better simulations. Maybe I can trick one of my over-achieving friends into doing this for me! Mech E's eat this stuff up.

The better option of course is to run both, side-by-side, and measure them with a laser thermometer or whatever. The main idea of course is to keep them cool enough to maximize efficiency.

I was kind of hoping someone would go the other route and try to "overclock" some of these using liquid cooling perhaps and higher wattage of course. I suppose it doesn't make a whole lot of sense except from the penetration standpoint, maybe.

 

[HughJassBud]

Here is a sketch of what the dimensions will look like with 16 COBS. I had to adjust them in from the edges a little to accommodate the pins in the vaulted hood. The big circles are the outer diameter of the heat sink. The little ones will be the holes where the holder and COB are mounted to the heatsink. The rectangle will be a sheet of aluminum.

I may still decide to move a little further than 3" in from the long side....maybe 3.1".

One little circle is missing in the second row, this was an accidental delete or something.

If I were running 12 COB's I think it would be roughly the same but with 1 row up the center instead of 2 off center.

Just the heat sinks will be ~27lbs for 16 of them. The tempered glass that came off was 12.2 lbs. I'll have to make sure these are secure and perhaps reinforce the sheet metal with some angled aluminum. Otherwise I think it should be ok.....

 

[sixstring]

@sixstring


Genius! This works really well too.

Thats a lil trick i learned from robincnn @northerngrowlights on fixing the pins.

 

[HughJassBud]

I did some more research because I wasn't real sure about the color vs radiated heat in these heat sinks as mentioned by @Toaster79 . As stated in the previous article it has more to do with the coating than the color. Raw aluminum is super inefficient at radiating heat. Anodized aluminum is pretty good. What I didn't expect or know is that it can make a fairly large difference in passive systems. Radiated heat has a much larger impact than I expected. So when looking at passive pin style heat sinks, make sure it is anodized.

Scholarly articles are super boring to read, but I found some if you guys insist. Instead though I like this one, it skips most of the math and just gets to the point.

http://www.qats.com/cms/2010/11/09/...ion-improves-thermal-performance-part-1-of-2/

 

[Toaster79]

Yes, anodized aluminum has better heat radiaton than raw but keep in mind it also has higher thermal resistance comparing to raw. Also self-adhesive thermal tapes are a bottleneck with removing heat especially if they're thicker. A well prepared mounting surface and good thermal compound are crucial to have efficient setup. I'm using copper-core heatsinks with soldered heatpipes. Ofcourse those are 120W rated CPU heatsinks but I'm also running my 3070s at 65W for penetration and lower costs of build. The COB core doesn't go much above room temp as those copper cores have maybe 30-35°C. You'll sooner feel uncomfortable with holding your hand in front of that COB than touching those heatsinks right next to the emitter. The only downside of my setup is Arctic Silver thermal glue as it has much worse thermal conductivity than AS5 compound. But it still does an awesome job.

 

[HughJassBud]

Yes, anodized aluminum has better heat radiaton than raw but keep in mind it also has higher thermal resistance comparing to raw. Also self-adhesive thermal tapes are a bottleneck with removing heat especially if they're thicker. A well prepared mounting surface and good thermal compound are crucial to have efficient setup. I'm using copper-core heatsinks with soldered heatpipes. Ofcourse those are 120W rated CPU heatsinks but I'm also running my 3070s at 65W for penetration and lower costs of build. The COB core doesn't go much above room temp as those copper cores have maybe 30-35°C. You'll sooner feel uncomfortable with holding your hand in front of that COB than touching those heatsinks right next to the emitter. The only downside of my setup is Arctic Silver thermal glue as it has much worse thermal conductivity than AS5 compound. But it still does an awesome job.

I was just looking for that information. I'm pretty sure this is a very thin anodize job, so I'm wondring how much it will impact thermal conductivity. I was trying to find something good about that subject. I am hesitant to sand or polish these because they are just so so flat. It really is incredible. These may be the flattest heat sinks I've ever had, razor edge flat.

Yeah, I really like your copper core set up. I guess you are kind of going the other direction and driving these a little harder. Maybe water cooling is the next step ;) For me it ultimately has a lot to do with running lower temperatures, so 50w per COB seems pretty ideal. However, I might set one up by itself and see how high I can drive it on a CPU heat sink with all the fixin's. It looks like fun! Maybe its worth it to have some run harder for the penetration to grow those trees @Purpletrain is talking about.

 

[Toaster79]

Driving them hard is the key to penetration.

In your hood, i would set them in different angle so tjey make kind of a sphere like a giant light bulb and mount lenses. You'll loose about 10% of luminous flux with them but the light will be directed some.

The only thing that bothers me with the type of hood is the airflow as there might be some dead pockets with hot air hanging. I would prefer suction on top of the hood and intake on the sides in the heatsink level and a few holes between the ones in the middle. Still not optimal but I'm guessing much better design?

 

[Toaster79]

There's tons of info scattered over at candlepowerforums.com but a pain to find it. I used to comb those threads over and over again swallowing tons of information but probably wouldn't be able to find the info myself, it's been a minute since. I used to build flashlight where thermal management is the only thing you should care about while overdricing those tiny emmiters like XP-C, XP-E, XP-G and simmilar including futher generations of some. Imagine driving a XP-G2 @2.5A without burning it and have it run as long as the battery puts out enough juice to keep it lit.

Here's what kept me busy before I started growing:

http://www.candlepowerforums.com/vb...tom-builders&p=4199876&viewfull=1#post4199876

 

[HughJassBud]

Driving them hard is the key to penetration.

The only thing that bothers me with the type of hood is the airflow as there might be some dead pockets with hot air hanging. I would prefer suction on top of the hood and intake on the sides in the heatsink level and a few holes between the ones in the middle. Still not optimal but I'm guessing much better design?

So, I agree about the dead pockets of air. I've had a few thoughts on this but I think it may not matter simply because of the heat sinks being used. These pin style shouldn't really require air movement, so the fact that there is a constant supply of air holding a constant ambient temperature should be enough without being too concerned with air speed over individual heat sinks. That being said, I think the COB's in the center should run cooler than those in the corners for example. Just how much cool will be interesting to see.

I considered putting some sheet metal fins or something in the hood to kind of direct the air towards presumed dead areas, but my eventual decision was to maximize CFM and limit obstructions. I'm not certain which is better, but my gut tells me the turbulence caused by all those big pin heat sinks will be enough to stir the air up and keep it all moving without any additional work. I'll get some streamers and tape them inside a hood to see how they blow around, this should give us an idea of where the air is going once I have these built. Old school approach :)

As for venting from a different spot or cutting holes to allow air through by the heat sinks. I agree this would probably be a better design in terms of cooling, but it wouldn't seal well. I try to suck in fresh air from my attic, run it through the hoods, and back into a different spot in my attic. This is partially to avoid the smell, you know keep it sealed in the room, and also to avoid sucking up CO2 when I'm running it (which I try to do consistently when the room is full). Almost forgot, I don't want to suck out the cool air from the room either. I have a split unit running and keeping things cool & dry. My house is cooled with a swamp cooler which is inherently humid. Where I can I like to keep the room pressure neutral to avoid sucking in humid air from my house. However, I do run an exhaust fan on a timer to turn the air over once in a while.

So, where it might be practical for some people to do it that way, and it may be a more efficient design, the trade offs aren't worth it for me right now. It's important to me that the hoods are sealed and don't allow air from the grow room into them.

This is something I have been thinking about though. It would be cool to design my own hood with venting so that I could make it specifically for this application as opposed to trying to fit it into existing HPS hardware. I am just working with what I have for now.

 

[sixstring]

I still think 12 cobs is more than enough for that hood/footprint.and i would think even a small cfm 6 in fan on low speed would be plenty of breeze blowing over those pin sinks to keep them cool.you dont really want them cold ,just keeping them from getting too hot is all you need.much much different than if that hood had a 1000w lamp in it.

 

[HughJassBud]

I still think 12 cobs is more than enough for that hood/footprint.and i would think even a small cfm 6 in fan on low speed would be plenty of breeze blowing over those pin sinks to keep them cool.you dont really want them cold ,just keeping them from getting too hot is all you need.much much different than if that hood had a 1000w lamp in it.

You're probably right. You're opinion is maybe the most valuable one here too, because you're one of the only people I have seen do really well with HPS first. It certainly would be less expensive to run 12 per hood if it will do the job adequately. Perhaps I'm too caught up in the wattage and grams per watt claims from others.

I have 3 x 6" inline fans I cool my lights with now. I think I will eventually consolidate all the LED hoods on to a single inline fan that circulates air from the attic through the hoods and back into the attic. I agree, it shouldn't take all that much cooling when compared to HPS. I just don't know yet though, not without building it myself.

Check this out. I just found out about it, but it was only published last month. Apparently people at Cree advocate discreet diodes vs the COB approach.



They are even nice enough to include a shopping list at the end for all the stuff you need to buy from them. It looks like it would be far more of a pain in the ass to wire one of those up than wiring up a series of COBs, but interesting. In any case, this is the first report I have seen where an LED manufacturer makes an attempt at a direct replacement for a horticultural HPS.

 

[sixstring]

Yeah i just seen that cree comparison at another site not long ago.
I def think you could cool 3 of those custom fixtures with one fan ,probably on medium speed if i had to guess.i think as long as your driving 36v cobs @1050ma or higher you will be good with just 12 cobs per hood.im really digging the production im seeing @1050ma and 1 cob per sq ft basically.

 

[jdb420]

1. @REALSTYLES, Northern emailed me and said that they have the 140 mm for 20 bucks, but she would do cheaper of you wanted 100. Just hit them up and tell them I sent you. That will save you some money instead of ordering them from china. There is a hole drilled in from the top too that is probably a half inch. That will allow heat to escape from your lenses. They also have the side holes drilled for mounting to the local channels. The heat sinks also have four threads at the top for mounting a fan if you want. The kits I got from timbergrowlights.com did not have side holes or threads at the top of for heatsinks for mounting a fan. Northern also said they just added new lenses to the website as well. Check them out. Their heatsinks are the best I have seen yet. I'll post pics soon. Thanks again for all the great info and I'll do anything I can to help you out.

 

[Dunge]

Check this out. I just found out about it, but it was only published last month. Apparently people at Cree advocate discreet diodes vs the COB approach.



They are even nice enough to include a shopping list at the end for all the stuff you need to buy from them.

The ability for an LED to operate without built in cooling fans is to me the most important aspect of this study.
(Internal fans is like buying a car that bursts into flames when it gets a flat tire.)
Can anybody give me a ball park on the cost of these 4 X engines as described in the report?

 

[jdb420]

Northern heatsink

 

[jdb420]

Holes for a fan too if you want

 

[Sativied]

(Internal fans is like buying a car that bursts into flames when it gets a flat tire.)
Can anybody give me a ball park on the cost of these 4 X engines as

Not necessarily, it can be more like reality, the car gets less efficient on flat tires. The heatsink can still be large enough to prevent the cob from being damaged.

Can anybody give me a ball park on the cost of these 4 X engines as described in the report?

(4x) 48 leds $320
HLG-320H-C1050A $120
4 optics CS14130_HB-IP-2X6-W $60
4 x SkinkPad PCB 1950-A at "send inquiry"... Let's say $50 total.
Frame, TIM, loctite, screws and wires $50
Heatsinks, aavid 62625 4 x 11.5", at $200 per piece... $800

The specific heatsinks they recommend are obviously expensive.
This one could work instead:
https://www.eltim.eu/index.php?item...on=article&group_id=10000167&aid=7576&lang=en
And then the heat sink cost would be $200 total.

May be able to get a better deal on the leds, but all in all it's about $650-750.

I like the design itself a lot, as well as the better spectrum, but there is a major catch in the cree ref design, they compared the light on 4x4' (16sqft) of a gavita at 1m distance, while in reality that gavita at that distance spreads out the light over more than 25sqft. It's a very expensive 600watt replacement at best, and then still doesn't compare to an efficient cob build.

So, I'm not sure if he understood me. I am also interested in running some more reds in bloom though.

I'm sure, based on his reply, he didn't. For more red (and some far red and less of that excessive blue, less green/yellow) simply get the 90cri, of either the 3000k or even 2700k. imo that is the obvious choice for anything but a veg-only light. 3500k 80cri will sooner than later be an artifact, its popularity is a direct result of people being blinded by efficiency at the light source. Which works, aside from the typical photoinhibition caused by the excessive blue, but with the latest bins and new vero and citizen leds one can build an efficient led light with a more optimal spectrum.

 

[HughJassBud]

So tired. I've had a lot on my plate just recently. I will try to get to this over the weekend and get these lights built. I am going to use the old housing from some 4 bulb x 4 ft T5 fixtures (ballasts are not good and they are missing connectors for the bulbs) to make a couple veg lights first because I need them the most right at the moment. I may not stay in this 4 ft format, but for now I think it will be OK and it saves me having to go find something else to use as a frame or the need to design and fabricate one.

If I have everything out for one project it is likely I will attempt to do both at the same time. I'll try to take plenty of pictures in order to provide a one step at a time approach for those who are interested.

I have ~20 healthy clones of The White that I will be putting in a tray under the new COB lights in Veg for a few weeks. Then they will move on to the big room where half will be under a 1000 watt light and the other half will go under the COBs.
I'm still constantly debating a 16 vs 12 COB setup with myself. Hopefully seeing some lights in action will help me make an informed decision.

 

[C21H26O2]

Welcome to the bright side. I used to run HPS and I had to stop growi9ng due to heat, electricity costs, etc. i stopped for awhile. After watching youtube videos, and following various experts, I was able to apply my own expertise and build my own DIY lights for both veg and bloom. I discovered as you have, that lower watts, is better for plants and lower cost. I have learned about supplemental lighting, i.e. Royal Blue, Far Red, Deep Red and IR as necessary to assist in total growth and development. Royal Blue creates tighter nodal growth, IR assists with THC development, Deep red assists with stem strength and development, and Far red is the sunset color to put plants to sleep.

I just changed lights, not my style. I see great growth, easily a gram/watt or gram/lumens/watt, I should say. I like DWC aeroponics system, custom design and build for faster development and growth. Single buckets, individual feed, just liike a pot only with aero clone spinners and pump, no air stones.. Now I used COB's at 700mA -1400mA for veg and tyhe lower the better. I also use 350mA driver for 36v cob's when I want lower heat and higher growth. I have 3 meanwell drivers from 350mA to 1400mA all dimmable for flexibility, all for veg. Bloom just full speed ahead. Scoty I need more power, Ai captain more power coming up. I run about 750 PPFD in bloom and it varies in veg. peace

I'm searching to learn how to build my own COB lights, can you recommend some resources?