i have several lights. the cheapo ones usually that run on aa. but someone recommended running a 14500. i’ve heard that 14500 cells last longer and recharge more times. so anybody have any input. these need to be rechargeable to thats the goal. well that and brighter flashlight with a reusable power source
If they are designed to run on 14500... You didn't tell us what lights you have? If they aren't designed for a 14500, they just might burn out instead.
What lights, specifically, are they? Some can handle a 14500, some can't. Most will definitely be brighter on a 14500. Most 14500s won't last longer (runtime) than a good NiMH rechargeable such as an Eneloop, although the brightness will be much greater.
there just little cheap 1.99 lights. i was just wondering which would last longer i guess i can surely mod anything if need be
i dont have any pics. and i purchased probly 2+ years ago. but the eneloops are what i think i’m gonna go withthey seem like everyones favorite aa rechargeable
In addition to what has been said:
Most 14500 are rated for far fewer recharges than most AA rechargeable NiMH.
You’ll lose the Eneloop battery before you reach its rated recharges. 
14500 usually give shorter run-times but higher brightness (sometimes twice the AA brightness). I personally don’t like them. I’d rather go NiMH for AA or 18650 for Li-Ion.
You need both .
Each has it's place .
some lights are so good on a 14500 it would be a shame to not ever have on in that case .
The Eagletac D25a I have does 1/10/107/176 on a eneloop
and about 700 lumens on a 14500
not running a 14500 in this case would just be wrong .