(If you’re interested specifically in AA size, there’s discussion overlapping this in a preexisting topic: Review: Fancy Flashlights Hi Current 17mm 1xAA Two Group Torch Circuit Driver )
Meanwhile, from suggestions there, I’ve tried 1.2v NiMH with amber emitters, with both the LDCH20 and the LDCH30 — similar descriptions, I’m not sure what the difference is supposed to be.
Neither driver is very happy with a single NiMH cell, though they work fine on low; medium is iffy, and high goes immediately into a flickering and mode-changing confusion.
So having gotten the wise advice that this input voltage is likely just too low, I tried and am getting good enough results with a couple of Tenergy “2/3 A” 1600 mAh NiMH cells — plus a 3/8 or 1/2” long magnet to fill out the needed length — to give the driver 2.4v. That works fine, giving the driver 2.4v.
So now I’m hunting for really cheap 2x18560 cheap hosts. Sigh. did I say cheap?
Also looking for a cheaper than usual source for SolarForce’s 1x18650 extension tubes (which cost around $7 apiece retail) and their 2x18650 battery tubes (which cost anywhere upwards of $13 apiece)