On Sat, 06 Feb 2016 18:57:43 -0700, Don Y
wrote:

Perhaps. OTOH, I never *buy* batteries to replace the (crappy)
batteries that come with the lights.

And, while I've not taken one apart to verify, I suspect the
lights rely on the internal series resistance of the batteries
to limit the current to the LED's (no "ballast").

That is true. They seem to work OK with the Costco AAAs so I will
replace the batteries when they go bad. I use them a lot tho.
When you take them apart, this is what you see

http://gfretwell.com/electrical/LED%20flashlight.jpg

All the LEDs in parallel with no resistor in sight.