For once in my life I was ultra lucky, and I won this Cyberpunk badge at Eurofurance.
Originally it came with a bulky triple AA battery holder on the back, but as you see you have the option to mod it your self to use Li-Ion battery with a charger board what cost cents.
Gladly I had some ultrachea power banks what I bought a dozen during Covid years when there were some ultra good deals out there, so this way the battery has some protection with that plastic shell... Otherwise its detachable as I usd self adhesive velcro on it.

more pics here: https://x.com/Kalakian86/status/183.....27195147845817