In my testing the 3 channel vs 2 channel efficiency difference was not nearly as much as many people used to think.
That said the 3 channel will have a fairly small window in the low/midrange where it has a bit of an advantage simply because it has a channel specifically designed for that output level.
At other output levels the only real difference is the input voltage.
Honestly there it is not even worth talking about driver efficiency. We are talking about a ~10% change in efficiency one way or the other depending on the exact output level. Considering the LED’s have a tolerance of 12% themselves there are simply better things to worry about.
I think, that if the second channel could be more powerful, the difference in the efficiency (both output and heat wise) could be worthful. For that many emitters (18), I think, 7×7135 is not enough - something like FET + 15 (or even 24) + 1 (or 2) could be better, as it would let the emitters run still fairly efficient on the mid-high output levels.
If I count 40W for a 18650 battery, and I multiply it by 4 (160W for the whole battery holder), then I divide with 18, that is still almost 9W per emitter, which is maybe around 2.6A per emitter, when I only calculate with the FET channel, and that is less than 80 lm/W then.
Maybe the XP-G3 variant could be driven harder with more efficiency, but I think, it would worth to design a 3 channel driver if SST-20 is also considered.
I know, that placing so many 7135 on the driver board would be difficult, but I think, a triple channel FET + 24 + 2 driver would be a very good fit for the MF01S.
The other end of this is that by the tint significantly improves when the FET kicks in, so switching to that earlier helps tint consistency and quality. At low current levels the SST-20 has a noticeable green hue. I would actually consider a 1 channel FET driver for the SST-20 if the low modes could be improved.
You edited the post I see.
As my testing of PWM efficiency showed, the old thinking that you could simply take the efficiency at 100% duty and apply it to lower duty’s is not how it works in the real world. The LED does not get as hot and thus the efficiency is improved at lower duty cycles.
For example at 50% duty it was only 10% less efficient then a constant current at the same power IIRC.
Although keep in mind that 10% was purely 10% more lumen output, it is not factor in the efficiency loss from the driver ect. With driver losses factored in the difference would be even less.
Can confirm. The tint isn’t very good until the FET kicks in. So below ~600 lm it’s not what I’d call white. But above ~600 lm, the tint is very nice. People who like a lot of light will probably love this thing.
Ok that’s alright then. My most used modes on the MF01 are 2 and 4 which are both over 600 Lumen. Btw when u say green do you mean greener than the nichia MF01?