Hello,
I am trying to understand the circuit below, but I am having trouble fully understanding its purpose. A set of 24V batteries are connected to the drain of the MOSFET. The source feeds a bus bar. Also connected to the bus bar is a vehicle alternator that supplies 28V when it is running. So, the alternator charges the batteries. The TVS diode seems to be for overvoltage protection. What purpose is the MOSFET serving?

I am trying to understand the circuit below, but I am having trouble fully understanding its purpose. A set of 24V batteries are connected to the drain of the MOSFET. The source feeds a bus bar. Also connected to the bus bar is a vehicle alternator that supplies 28V when it is running. So, the alternator charges the batteries. The TVS diode seems to be for overvoltage protection. What purpose is the MOSFET serving?
