A battery management system (BMS) is essential in a lithium ion battery build. Li-ion batteries are much more sensitive to voltage than lead acid, and can be dangerous if over- or under-charged. It protects against over- and under-voltage as well as over-current, and ensures that the cells are balanced. This BMS is for a 20S (74v nominal) lithium ion battery, and allows 60 amps continuous discharge and 30 amps charge. That's 4440 watts of continuous power. Wow!
To wire, you will need to solder battery and charge/load ground to pads on the board. You will also need to tie each of the balance leads into the individual battery cells. Note that this does NOT have provision for separate charge and load, as some boards do. Balance wiring is not shown, but is included.
This BMS is suited for smaller projects, but don't expect it to be adequate to protect a large build such as an off-grid power wall. This is perfect for eBike and scooters up to 1000 watts, as well as RC projects. And the case is waterproof, so you can ride anytime, anywhere.
See photos for specifications.