BMS stands for Battery Management System and the one built into the S16 Pro has the all the features you need to be able to monitor your battery health extensively from within the King Song app. The BMS has temperature protection functions so that your batteries do not overheat. Using the King Song app you can monitor each battery cell individually to ensure that your batteries are in good condition. Viewing the voltage of each cell allows you to see if your unit has any dead cells and you can make sure that your batteries are fully charging.