11.1V battery charging with optional solar panels

Question

We (beginners) are trying to build a paddle streamer with stepper motors and drivers salvages from an old 3D printer. We would like to drive the motors with 12V (or 11.1V) and the control electronics will requires 5V/3.3V (ESP8266 for remote control and/or raspberry pi zero for video streaming from a camera on the boat).

I was thinking of using 3 cell Lipo battery in series but during my research I have found out that each cell needs to be charged separately to prevent over/undercharging. We also would like to have an optional solar panels on the streamer as it will float around freely in a pond most of the day.

We were wondering, what would be the best approach to power such a boat? We are afraid to blow up the battery by making bad choices. For single cells, there are modules, which have all the necessary features (over/under charge protection, overcurrent protection, allowing discharging and charging at the same time? etc.). It has got complicated with 3 cells.

edit: sorry if the question is not specific enough. I can delete it if not fit to be asked here.

Answer 1

You need two things:-

1. An MPPT solar charger designed for 3 cell Lithium battery.

2. A BMS (Battery Management System) board with balancing function, wired onto the battery. This keeps the cell voltages the same so the whole battery can be charged at once, and protects against over-charge, over-discharge and over-current.

You should also have a voltage monitoring device to warn you if the battery is getting low. Perhaps it could be programmed to bring the boat back to shore while the battery still has enough capacity to make it back!