The easiest conditions to monitor are the catastrophic—the battery is on fire, there is a short with the load, the charger is sourcing too much current, etc. Other conditions may be more subtle—is it too hot or cold to charge, has the cell been permanently damaged by charging? The FET drivers are functionally tied to the status of the cell voltage within a battery pack. The state at which the BMS is in (load state or charge state) and the digital/analog comparators that monitor temperature, current and voltage windows control which FET, if any, are on. The diagram on this slide shows the cut off FETs that are part of the cell FET driver. The circuit connection allows for the charge current and load current to be significantly different via the use of two sense resistors.