ArturoSC1
September 15, 2020, 3:44pm
50
idleprocess:
I’m fascinated by the FW21 Pro to the point I’ve nearly purchased it more than once, but I’ve got my doubts that it will hit the claimed 10k lumens on turbo:
Assuming 3V XHP50.2 , maximum rated current is 6A which just cracks 180% nominal lumens with top-binned emitters hitting 1328 lumens at 25C or a still-optimistic 1200 lumens at 85C so at max current you’re looking at 2160 lumens; Some hazy - and probably far too generous with diminishing returns and all that - math dividing 2160 by 6A suggests 360 lm/A thus you’re looking at ~9.26A to hit 3333 lumens per emitter or 27.8Aillumn ‘helpfully’ suggests NCR18650GA (10A peak discharge) and INR18650-35E (8A peak discharge) as compatible 18650s which probably aren’t going to do much for turbo, although they do recommend the INR21700-30T in 21700 which will push 35A
However, the review indicates that output is closer to 7000 lumens so the current situation changes:
2333 lumens - 2160 lumens at 6A = 173 lumens / 360 lumens per amp = 480mA deficit so peak current demand is 6.48A x3 = 19.44A … a much more comfortable overdrive level
20A is within the realms of more humble cells such as the Samsung 25R which I have many of
Thus … is this a real bump from the D4 / D4S / FW3A in terms of output - either at turbo or at a brightness level the light can actually sustain?
Regarding the D4 the FW21Pro is able to maintain many more lumens, without a doubt, in fact only with the cooling that provides keeping it in hand is able to keep indefinitely the 2.8A mode that in mine represents about 1250 lumens