I test the quality of the LED chips always by operating at extremely low currents. This can be seen when the LED chips sorted out relatively poorly (binning) have been. So when one of the two members appointed 30w COB modules is at a very low current (zB.5-10mA), a LED chip almost from the others shine quite brightly. This is not necessarily a sign of a good quality control. Other hand, one can in prices do not expect that every COB module contains nearly identical and well-screened LED chips. I've already bought some of these COB modules and most are equipped with almost the same price with better stocked chips. The new round COB modules are at least for the purchased of me copies, still significantly better in quality. These individual LED chips light up even when operating with single-digit mA values below 5mA still equally bright.
