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 14S (51.8v nominal) lithium ion battery, and allows 30 amps continuous discharge and 20 amps charge. That's 1500 watts of continuous power. Wow!
The board comes with 10AWG wire to connect battery negative and charge/load negative. 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.
The balance function is suited for smaller projects, but don't expect it to be adequate to balance a large build such as an off-grid power wall. This is perfect for eBikes, scooters, go karts and other higher-power builds. And the case is waterproof, so you can ride anytime, anywhere.
See photos for specifications.