This is an enclsure / battery system for a LilyGO T-Deck which uses and charges multiple 18650 batteries. This enclosure can sit in a window charging the batteries either via solar or USB. It charges battery cell #1 first, then when bat1 is full, it charges bat2, and when bat2 is full it eventually charges bat3. Any of the 3 batteries can power the TDeck. It can operate with no batteries as long as USB is providing power. The circuit board includes - over and under voltage protection - short circuit protection - multi stage charging - battery temperature protection - charging via solar or USB These files include the PCB layout and 3D files for an 18650 based T-Deck enclosure. 3D source files can be found at onshape [Here](https://cad.onshape.com/documents/b289702058d3b69984c9ded4/w/4e1c5bb6efe28ab1e1699733/e/336c687f36e879030984626b?renderMode=0&uiState=65d20786c6b9344a8c9a8531) PCB files can be found at EasyEDA [Here](https://oshwlab.com/easyeda_jh/tdeck_18650_charger) GitHub copy of files foun [Here](https://github.com/jharvey/T-Deck_JH/)