From the testing with COBs and modern LEDs, I lowered my recommendation to 25cm²/W for active cooling and 75cm²/W for passive cooling, assuming you are using a passive cooling friendly heatsink. These are just general guideline, you could allow the COBs to run a lot hotter and they would still perform well, especially Veros. With these recommendations I am aiming for very low temp droop, 2% and under for those running medium-soft.
I would like to incorporate the C/W/3" data by translating that data to cooling/1000cm² chunks. But as
@getsoutalive pointed out, it is very complex in practice. So our best bet might just be to get a few chunks of different profile sizes and test them with our actual conditions (horizontal orientation, slight air movement and very small temp differential between heatsink and ambient).
Here are the figures for C/W/1000cm² chunks. The smallest numbers should be the most passive cooling friendly, BUT again these numbers are based on no air movement, vertical orientation and super hot heatsinks, much different conditions than we will be dealing with. Really, this calculation is not valid for the profiles with large changes in length and the assumptions made about how that affect heat flow, but I went ahead and did it anyway.
1.8" -> 1.4 C/W/1000cm²
2.08" -> 1.8 C/W/1000cm² (great for small COB passive vegging due to cost and spread)
3.5" -> 1 C/W/1000cm² (my fav for active flowering due to spread and large COB passive vegging)
3.945" -> 1.6 C/W/1000cm²
4.23" -> 1.1 C/W/1000cm²
4.6" -> 1.46 C/W/1000cm²
4.85" -> 1.37 C/W/1000cm²
4.9" -> 1.2 C/W/1000cm² (my fav for passive flowering due to spread)
5.375" -> 1.22 C/W/1000cm²
5.88" -> 1.4 C/W/1000cm²
7.28" -> 1.22 C/W/1000cm²
8.46" -> 1.345 C/W/1000cm²
10" -> 1.3 C/W/1000cm²
10.08" -> 2.22 C/W/1000cm²
12" -> 1.46 C/W/1000cm²
Anybody here ever use it?
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