AquariusPanta
Well-Known Member
I imagine replacing the Cree 3070 ABs with a different COBs series, such as the Vero 18 or 29, may or may not require either more cooling or more aluminum, depending on known values of thermal resistance.Increased power again, dissipating 108W, same heatsink, now 50cm²/dissipation W
Ambient temp 22.5C
Heatsink temp reached 40C with no airflow, convection only
light loss was 7% versus ambient baseline
Added 120mm fan running softly at 5V (dissipating .463W) consuming .555W.
Heatsink temp stabilized at 28C
light loss was 3.36% versus ambient baseline
I increased fan power to 9.35V (dissipating 1.56W) consuming 1.87W
heatsink temp stabilized at 26.5C
light loss was 2.94% versus ambient baseline
So when you work the numbers we get:
baseline efficiency 42%
Passive cooling 39%
Active cooled 5V = 40.4%
Active cooled 9V = 40.1%
Because of the white COB's surprising performance with heat, the active cooling had less benefit than expected and once again the 5V was actually better than 9V. This test is important so I intend to repeat it with the 5.88" profile next time. I have a 12" length with a 140mmm fan and a pair of CXA3070 ABs mounted.
With the 5V/9V testing, are you simply supplying the fan(s) with a 5V and 9V PSU? If so, what amperage are they ticking at? I've had bad luck with ordering PSUs for fans (Intel Fan/HeatSink), with stated currents NOT matching operational currents (fans not spinning completely).
Also, are you performing the tests in a tent or a room, such as a basement? What are the dimensions? I find this all to be relative in best understanding your results.