CobKits
Well-Known Member
nobody tests them that low in a sphere - every measurement costs big money and they are usually only testing at normal operating currentsAny proof here? I keep seeing people say to drive COBs @ 5-10w for 65-70% efficiency but when we finally get any sort of sphere data the numbers are far lower than I thought.
i believe 60%+ efficiency is easily attainable, heres some curves of single chips in a 20" sphere (not cree but they all generally have the same shape)
so *IF* you have a cob that is 50% efficient at 50W you can see that its easy to get to 60% at 20W, but to get to 70% youd need to be well under 10W
i dont see anybody hitting 240 lm/W (~75%) with any cob at a realistic operating level (and ive tested several DB bin cobs - theres nothing magical about them -nor does PCT go anywhere close to that low of a current). most all cobs converge at low currents so if youre trying to break efficiency records by running under 10 W/cob you want to be stacking up $10-12 cobs (or single die SMDs like the quantums), not $40 crees
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