Emisar 21700!!!

[clientequator]

@adam7027

As I recall, E21A is a fairly low Vf emitter, thus, if a linear driver is used (even PWM-less), Vbatt - Vf difference is fairly big, so even if E21A and 219B 9080 has similar efficiency, E21A shows better these differences in driver efficiency - showing the superiority of the buck driver used by FireFlies more spectacularly. With keeping these measurements in mind, K9.3 seems definitely overpriced for me, even it is a very complex and expensive design. I have big hopes for the FireFlies E07X. If I get those with SST-20 4000K and 2700K (or hopefully ~3500K), I will trade my two D4SV1.

You are correct! I made comparison using texas_ace chart:

https://budgetlightforum.com/t/-/50279

https://budgetlightforum.com/t/-/44574

Because lumen brightness is low (600lumen for K9.3 / 9 led and 900lumen for E12R/12), I use lowest value on the chart per led which add up to about the correct total brightness:

E21A is 2.63V at 150mA

219B is 2.72 at 150mA

so I multiply by 2.63/2.72 and I get 34.6% more efficient for buck driver. I think most likely this is very simple estimation and not accurate, but even if it is different by +-10%, the effcieincy for buck is clearly shown in this comparison. K9.3 with buck driver would be amazing!