Is there any 14500 cells out there that have a build-in charger and can be charged on a typical li-ion charger?
I have 1 Wuben cell that as Micro USB built-in charging and it charges without issues on a normal charger.
Also 1 Lumintop cell that does the same thing too 
Confirm the Lumitop will charge via USB or suitable conventional charger.
Most do, but most are also quite a bit longer. My Wuben 14500 doesn’t fit any other lights I tried it in.
You may also check Nitecore NL1475R, 750mAh
Klarus also has 800mAh that fits the criteria. I believe it’s the Sanyo UR inside.