I have one of those RYOBI tool kits ... you know the ones... with the circular saw, reciprocating saw, 1/2" drill, and flashlight, along with a charger and a couple of batteries. Well, aside from having found that the bulbs for the flashlight are a mite hard to find ... I find that if you leave the flashlight turned on and go away, returning after the battery is discharged, you might as well toss out the battery, because it can no longer be recharged after being totally discharged, even once, and even with a brand-new battery.

The saws, drill, chainsaw, string trimmer, etc, all simply stop being useful after the battery is sufficiently discharged ... the flashlight, however, draws the battery into deep discharge ... a condition from which it can't recover. If you're designing with one of these in mind, you'd best monitor it for voltage ... or something ... else it'll be a costly paperweight.

Just a word of caution ...

RE