My back-of-the head calculation was: 1.1V (already under load! +losses) to 3V@1A = 3A in —> Eff. dipping below 50% —> 6A in. (And then further V_in drop etc.)
This particular converter shuts down at 4A I_sw, that’s where it ends.
When the efficiency curve is that steep it doesn’t make much sense to make detailed calculations anyway. It’s a dynamic system, and it just goes bad, fast. One problem exacerbates the other and vice versa. That’s the bottom line.
You could, in theory, run 2 switchers in parallel and share the load, but then the battery still remains the weak link.
With all this in mind, what’s a reasonable output?
I think the sweet spot is around 200 lumen, a good balance between output and runtime. Seems to be what most AA lights have settled at. (Although some still step down from that, for some reason.)
Keep in mind, 90CRI has a bit of an impact too.
This is turning out great. Now I’m definitely interested in 4 or 5 of these especially if the price is not so far off the SP10B. Also interested in a couple of drivers if they become available for purchase.