I wanted to run mine at Max which is 80w and still have decent life expectancy at less then a $1 per watt. I really like the cree. Good clean efficient light. But I don’t think I would notice a difference in my grow for the extra $100.
$100 maybe. I overdrive mine a bit. I liked the numbers over the vero29. I also have a preference for Cree. I have used a lot of their products in numerous flashlights. The vero29 is very competitive as far as numbers go. If Cree wasn’t an option, I would have been just as happy to go with the Vero29’s. @Daddy
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And we are both gonna rock our grows brother 
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Sounds about right. My sink temps were generally around 100f. Even at 120f your figure with a good thermal joint case temps are probably a few degrees higher. Even at 130f that’s like 55c, well below where they’re rated for 50,000 hours. Plenty good there.
Did you go as far as checking the temps on all or most? And see similar swings in readings across canopy? Only reason I ask is that data sheet shows like a 4-5% drop from 25c-50c. And the same from 50c to 75c. Yet you’re seeing a drop similar to what would be from 25c-75c but only changing the temps a couple of degrees. Seems weird no?
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My 2 centers are the warmest of course and out sides. Are the coolest because of fans for the plants. My light is blended and each plant is in the center of 4 lights . So I can never get perfect light measurements because the same location with a slightly different angle will give me a higher or lower reading. When the cases are warmer though I do have a measurable difference in less out put. 80w is 80w no matter if heat or light correct? So the hotter they get the more heat and the cooler…more light 
Example …before fans turn on, 72k-75k lumens. Fans on 10 minutes and it is 80k lumens.
@Daddy @dbrn32 all out of likes also. Following along though. I know it’s been said and I’ll say it again… What’s with the limited likes??
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You would think. I just felt like your readings were a little skewed compared to data sheet. Going off the 25c probably not ideal because I think that’s a pulsed measurement. But I’m pretty sure the others are hard running measurements. 91% of listed luminous flux all the way up to 75c is solid, but that doesn’t seem to be what your tests are showing. I’m only really asking because if it’s just an issue with the accuracy of your meter or measuring, than no big deal. If it’s a deal with the accuracy of the data sheets, then I have a small issue with that. Catch my drift?
As far as the more light goes, it’s definitely more light. Is it more light per watt when fan is calculated in? Rough estimate says it probably is, but so is running at running at 70 watts or lower. That’s just all the stuff we try to take into account for our builds right.
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I understand what you are saying and all of my measurements are not lab quality either. Measuring at the heatsink too vs base and a amateur light meter. All I can say there is a corresponding drop in light output as heat increase so it’s best to keep as cool as possible…within reason of course (liquid nitrogen not required)
For sure brother!
I tried my fixture with passive heat sinks, then I put a little desktop fan in line with it to blow air down the fin channels. BIG improvement in the temperature. Then I ducted the fin channels and hooked it up to my exhaust fan. Not a very strong fan, but now the heat sinks are barely warm to the touch. Maybe 90 F!
On that large temperature / lumens difference: Do you have a good thermal connection between your COBs and the heat sink? If not, the COBs could be running a lot hotter and getting into the lower flux range of temperatures. I went to a lot of trouble to get a good thermal connection. Polished the heat sink contact area mirror-smooth, used 1/4" copper heat spreaders under each COB (again mirror-smooth), plus thermal goo between COB and copper, and copper and aluminum.
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Cleaned and prepped well and used the thermal transfer tape. The cobs do deflect quite a bit if over tightened though so have to be careful in that regard.
@dbrn32 thought you should know I went ahead and purchased 10 more of the Citizen CLU048-1212 90cri 3k COBs and associated heatsinks and holders. Going to get the stuff in place to build out the rest of the fixture for the next grow.
For now I’m thinking I’ll just build two more rails exactly like the one I already built, each with it’s own driver.
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Woohoo! I love it, and think your plants will too!
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Looking for drivers seems like I found the best price + shipping at Sager. $93 for the two drivers plus shipping which looks like it will be under $10 for UPS ground.
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What was arrow? Last I knew they were like $46 and free shipping.
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Crap I didn’t check Arrow. Let me go look.
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Arrow is actually more…
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There was a point in time when I would put money on them being cheapest, apparently not anymore lol. Glad you found a better deal!
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