OK I have the CXB3070 3500K BB from PLC and a CXB3590 3500K CD from Kingbrite. I decided to scrap my original data and start over with a better methodology. This time each COB was mounted on the exact same heatsink and the heatsink was hung using chain with the holes marked so it hangs exactly the same every time. The measurements were pulsed and taken with a distance of 12" from the LES to the surface of the Apogee sensor. I used 3 multimeters to monitor PAR, voltage and current at the same time. All the COBs are brand new and this is their first use. Each curve represents at least 10 measurements.
At one point I received a sealed CXB3590 50 pack from Kingbrite, but this test was done with a CXB3590 3500K CD that did not come from a sealed pack so it is a "trust" COB. I think these results confirm we are getting top bins as promised from Kingbrite and I have full confidence in Cutter as well.
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The CXB3070 3500K BB was provided by Pacific Light Concepts, thank you!
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The CXa3070 came from a sealed 100 pack from Arrow. (Very interestingly this COB has been shipped from China to the Netherlands to the US to Australia and back to the US.)
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The curves are "compressed" and I am not exactly sure why that is. I think the same goes for temp droop so that explains why measured temp droop always seems to be a bit lower than the spec sheets predict. So these curves cannot be used to extrapolate actual efficiency at low currents as I originally hoped, but they do confirm the continual increase in efficiency even at very low power. So it looks like we need an integrating sphere to get the absolute slopes (or we trust the CREE datasheets).
I plan on adding Vero 29 3000K V2.0, CXB3070 3000K AD, CXB3590 3000K CB, CXB3590 5000K CD 80 CRi to the graph but this is what I have so far. Thankfully, these results agree with the datasheets.
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