An energy storage system for a vehicle, includes one or more battery units for storing electrical energy; at least one high voltage switch for connection and disconnection of the one or more battery units to at least one load, such as an electrical machine; a fuse for disconnection of the one or more battery units when the energy storage system experiences an overcurrent being above a predetermined overcurrent value. The energy storage system is configured to during use, identify if a condition has occurred which requires immediate shutdown of the energy storage system.