Serviceable 1s2p 18650 battery pack design I made for a headlamp.
-learned some FreeCAD
-swappable battery pack
-swappable cells, just 1 screw to remove cover
-strain relief
-USBC charging, charging LEDs
-overdischarge protection
-board snaps into place very securely
-belt clip to keep weight off headlamp headband
-telephone cord for further strain relief
-reasonably protected against internal shorts and a lithium battery fire
-retardedly posted this to /o/ first by mistake