I have 3x 18650s wired in a series, connected to the BMS seen here. The two outputs of the BMS are wired to a MOSFET that drops the voltage from 12 to 5, in order to power an Arduino Trinket Pro.
During prototyping I was using your basic DC jack to connect to the Arduino and charge the battery pack. However with the 3D printed part I have this all in I am using a different battery contact to connect the battery pack and Arduino.
Now I am needing to find a different way to charge the battery pack, preferably through a micro USB or USB C charging port, like you see on portable power packs.
I've picked up the TP4056, seen here, and the USB C version. My question is can I / would it be a good idea to splice off of the BMS outputs, and insert a diode into the connection between the battery contact that connects to the Arduino and a diode into where the TP4056 runs.
The first time I had tried it with a standard micro USB port, no diodes, which heated up very quickly.