Differences in measurements result from many reasons. Not only from the methodology but also from the differences between the various models. It can be affected by the ambient temperature, the battery used, the centering of the LED …
GTmini has a FET driver and the internal resistivity of the elements is very important here. The manufacturer gives 17W and 4.5A. My GTmini with Samsung 30Q received 5.8A (clamp meter). This is one of many possible reasons that the end result may vary. Measurements are made with the X-Rite Eye one Pro calibrator which is more accurate than most cheap light meters. Thanks to this, I can also precisely specify the color of light which in my opinion is one of the most important features. If someone thinks this is not very reliable, then he has such a right, but to call me a liar? :frowning: