SAKATA 3D PETG filament is suitable...
18650 XTAR MC2 Battery Charger
18650 Li-Ion Battery Charger
DC-DC Boost Module with microUSB Input, Charging Function for Li-Ion Batteries and USB Outputs
Turnigy Accucell-6 50W 6A Balancer/Charger LiHV Capable
The Micro-USB Li-Ion Battery Charger is a complete constant current/constant-voltage linear charger for single cell lithium-ion/Lithium Polymer (LiIon/LiPo) batteries.