It is true, some of these tests will have a certain margin of error in them. This test is particularly difficult when using a pair of drivers because I cannot monitor the current of each driver as it varies with driver temperature ( I am working to remedy this). In order to get a really accurate test, the driver has to be warmed up before hand and the current should be noted as you take the pulsed light measurment. Once the COB/heatsink is thermally stable, I cool the driver back down by hand until it matches the current at the beginning of the test, and then take the light reading. Matching the driver current is critical to get accurate repeatable results. Another option is to use a dimmable driver, a big time save but the biggest one I have on hand is only 1050mA and I needed a pair of 1400mA.
Another issue with my testing is the lack of airflow during the passive cooling tests. It really is the type of test that should be done in the grow space but the other lights would interfere with the results one way or another. So I believe the passive cooling numbers I posted would be better in practice. When I check the temps of my 10.08 heatsinks in use, they are 27C. In the test, they were 33C.
So to perform the test, you would need a
luxmeter, an accurate
current measuring multimeter or dimmable driver, and an accurate digital thermometer (helpful but not necessary). It is critical that neither the COB or luxmeter has a chance to move between the pulsed measurement and the warmed up measurement. You can attach the meter to a tripod and hang the LED above it. Or you can perform the test on a flat surface, a silicon mat or something non skid to keep the components still. You can get a heavy silicon mat from Walmart for $6, just got one for my soldering bench.
