I have a device that runs on a single cell Li-ion / LiPo. The physical case for that device allows me to put in one to three 18650 cells. Unfortunately given the disposition of the cells, I can't buy a 2 or 3 pack already assembled.
The device already has a charging circuit. The maximum load will be 300 mA and the maximum charge current will be 500 mA.
Given the above, if I connect 3 cells in parallel (1S3P), do I need a BMS (Battery Management System) or any additional protection circuit?
I'll take care to have them at the same voltage level before connecting them together to avoid current flow between the cells.
TL;DR; Does a 1S3P Li-ion 18650 pack need a BMS?