heck, i have a light that runs 120ma on LOW mode, and a big 26650 in it… i turn it on at DARK, and turn it off at morning… by morning? it was still 3.7v, having started out at 4.2 ish…
by contrast? theres some light rockets the guys here have made that probably would not last more than a couple minutes, lol
also, lithium batteries capacity (assuming the manufacturer doesnt LIE in the first place, lol) isnt a straight line on a graph. By that, i mean this…
lets say you have a .5amp light…. thats the draw on the battery. You have a 2000ma battery capacity. Simplified wisdom says 500ma (half amp) draw out of a 2000ma capacity battery will yield 4 hours…
also, a 100ma small light? on the same battery? should by this reasoning give 20 hours…
its not linear like that. The battery acts like a higher capacity battery at lower draws, and as if it had less capacity at higher draw.
also theres the matter of capacity vs high rate…a battery rated for 30amp short high draws, will likely have less capacity than if it had been designed and rated for only 5 or 10amp short high draws…
reccomendation and reputation are everything… which the lads here hand out freely, of course.