My latest creation

[Rahz]

I managed to get it suspended at room temp and took some readings. Ambient temp 24C. Cob Tj is 32C on one end and 38 on the other. Exhaust temp is 28C. I took a reading inside the electrical compartment at 34C.

The outer emitters are 8 inches from the edge of a 2x4. The lamp is 2 feet from the "canopy" in the pic. Could probably lower it a little but wouldn't want to run it much lower. This is the 2nd 50 watt emitter lamp I've built and am really impressed by the intensity. I haven't used emitters with higher wattage than 50, but suspect at some point the intensity per cob can become a problem. I would probably want to run this lamp about 18-20 inches in flower, maybe a little closer in veg mode.

I have put some thought into custom built reflectors and have access to a powder coating oven. Will hopefully get to that soon.

For the most part I'm happy with the temps. I'm wondering though whether there would be some improvement if I gave the air channel a 1/4 - 1/2 inch space above the heatsink. A lot of air would flow over the sink but the overall throughput would increase. Any guesses on how it would affect temps?

 

[CanadianONE]

Have your though about having higher CFM on intake fan VS exhause fan this way you would have positive pressure, Not talking a big difference but just enough so the intake is pushing a bit more in then what being drawn out. Giving a little more contact time to transfer heat to the air. Just a thought.

 

[gk skunky]

Would there have been anyway to put the fans as end caps? Then you still have one pushing and one pulling but putting more contact with the heat sink and creating essentially a mini wind tunnel. looks good though.

 

[Rahz]

Have your though about having higher CFM on intake fan VS exhause fan this way you would have positive pressure, Not talking a big difference but just enough so the intake is pushing a bit more in then what being drawn out. Giving a little more contact time to transfer heat to the air. Just a thought.

Interesting idea. Hadn't thought of that, but the fans are already over 40 decibels so I'm not sure I want to take the next step up.

 

[Rahz]

Would there have been anyway to put the fans as end caps? Then you still have one pushing and one pulling but putting more contact with the heat sink and creating essentially a mini wind tunnel. looks good though.

I think there could be some advantage to vertical on the end... but getting the majority of the air through the fins would require some creative enclosure design. I think most of the resistance is just due to pushing air through a 36" conduit of only about 3 square inches of air space

 

[gk skunky]

I think there could be some advantage to vertical on the end... but getting the majority of the air through the fins would require some creative enclosure design. I think most of the resistance is just due to pushing air through a 36" conduit of only about 3 square inches of air space

I wonder if just a slight angle to the intake fan towards the heatsink could achieve this while providing a little resistance and spread over the sink. Though that May require an offset. Idk

 

[CanadianONE]

You could simply dial back the exhaust fan just a tiny bit to achieve this and it would lower you db of one fan in the process. Worth a shot. Maybe the extra contact time will lower temps a degree or two and save on power (minimal I know) and noise.

 

[CanadianONE]

Also do you have the part number or a link to your fans. Would like to have a look at the datasheet.

 

[gk skunky]

I'd disagree and say that would potentially raise Tj and obviously case temps. Air speed and exchange rate is more important when it comes to air cooled applications. Just like air cooled engines and water cooled radiators. Both will build heat as overall airflow decreases. Same concept. More air you move the better it performs. given there are thermal differences and the air being pulled through is constantly a lower temperature than the case temperature.

 

[CanadianONE]

Very well could be right. I was just thinking if the air is always cool coming out the exhaust that maybe it could handle a little more heat transfer before being pulled out. Maybe my thinking is totally off. If you slow the fan down too much that so the air dwells for too long then it will raise temps but I wasnt talking about a huge decrease in fan speed just a very small fraction even just a CFM or 2. Just enough to force that air around inside before its sucked out. Think of a sponge if you just dunk it in the water fast and take it out will it be full of water or could it have stayed in the water for a second longer and pulled up more moisture. Just an idea and maybe it wouldn't work lol either way I love you build. Looks well constructed.

 

[a mongo frog]

I've had an idea in mind for a while and had to build it. I wanted a PPFD of just over 800 in a lamp made to provide coverage for a 2x4 tent and this is what I came up with.

View attachment 3477863 View attachment 3477864

Everything is over powered and underdriven. 2 HLG-185H-C1400s powering 6 Vero 29 3500K at 1.4amps, Two 120mm fans each with their own 12w power supply. Both fans are pushing through the same channel so if a fan or fan supply goes bad the lamp keeps running without much change in CFM.

Veg mode switch flips between 1.4 amps and .560 amps.

EMI power inlet and power outlet.

I was curious how the cooling situation would affect the cobs, hoping the temp readings would be similar from one side to the other. With ambient temp at 30C the first cob in the channel has a Tj reading of 39. The last cob in the channel reads 44. More of a rise than I was hoping for, but well under typical even in a hot room.

All aluminum construction and fairly light considering it has a 36" piece of the 4.6 profile heat sink in there.

Material cost plus shipping was about $500.

I have no use for this light as I'm full up at the moment. I will likely end up ebaying it. But not before I show it off and do some more testing. Seriously considering ordering a par meter.

Would this lamp perform better then an 8 bulb t-5 to grow 2 decent size mother plants with? It was mentioned that you were trying to get a 2x4 area, same area as an t-5 really. Was just wondering if the lamp would dust a t-5 for 2 moms.

 

[Rahz]

A basic lumen comparison, The T5s would output 40,000 lumens at about 100 LPW. For a basic light stat comparison this LED lamp is 100w less for 3000 lumens more. But the T5s don't radiate directly downward and need a high degree of reflectivity like HPS. My experience is almost double yield using LED with Vero version 1 at nominal current, PPFD of about 750 and this lamp should average about 840 across the canopy.

But although CFL doesn't seem to do well in flower, I notice very little difference in veg between CFL and LED as the plants light needs aren't as great. I think 400w of CFL in a 2x4 is excellent for veg/mother. It's just with LED you could do similar with 200w.

This lamp was designed for flowering so probably overpowered for veg only or mother chamber. The veg mode on it is 125 watts and I will be testing it in a couple weeks to see how well it does. I have a 200w diy I just started using in a 3x3 and veg in soil has been good.

 

[gk skunky]

@a mongo frog T5s are great for veg and clones. Great spread too. But you could still get by with less going LED. For example, I run about 660w LED in a 4x4 for flower. I run perpetually and pull over a lb a month. That is all supplied by a 2x4 clone/mom/veg area using only 4 A19 5000k cheapo Wal-Mart great value brand leds(~$10/ea,but i only use them because they were free. Figured try the house warming gift out. Lol Just get the better cree ones from home depot if anything.) screwed into a 4 bulb cheapest vanity/sink light fixture Lowe's had to offer. ~$24 I want to say. Not to mention less than 40W... LOL not saying what i have is ideal or even great just showing what is possible. So something like rahz's light could annihilate that size area. LOL