I was self-employed for decades (and a mechanic for over 3 decades) .... ie..I was the checkbook for needs of employees. I completely understand when inexpensive + quality + reliable + efficient have to come together.
Stating the above, and the fact that you seem to understand flashlights, I will give you my opinion:
- A built in charger will only give you more headaches than anything else. The budget lights often have suspect circuitry, as well as the fact that micro usb ports and plugs are fragile (think cell phones)
- Relying on a built in charger in an industrial application may seem convenient but that also means that the light will be out of commission during charging
- A built in charger will only increase the cost of each light.
- My current employer provides lights with built-in chargers (Streamlight Strions and now Fenix E40UE's) and they still do not have the flexibility my coworkers would prefer
My recommendation (based on my prior experience and that I currently use the same in my current capacity at work)
- Convoy S2 (use code BLF for 8% off) - Reliable and tough...see Simon's video (the manufacturer)
- Eagle Eyes A6 (use code BLF for 8% off) - one of my favorites...see the current group buy :)
- Samsung 26F Protected batteries (use code BLF for 8% off)
- Xtar MC1 micro-usb individual charger (if mechanical contractor and employees at multiple locations)
- Enova 8-bay charger (if for use jobsite with trailer)
If you follow that recipe you should be right at $25 complete per person/light and should you "lose" a light to mishap or just misplacement than you are only out a minimal amount PLUS the benefit of when battery is exhausted you would just "change and go" ...the only time you would open the light.
Not gospel but I hope it helps :)