Postcrash fires are a frequent cause of death in otherwise survivable automobile and aircraft accidents. The idea of the ICED (Internal Circuit Emergency Disconnect) battery  is to eliminate electrically ignited postcrash fires by means of an inertial interrupt device that will disconnect the active circuit at the battery if an accident should happen. The design of the prototypes that were tested and the analysis of the disengagement performance will be discussed. A ballistic pendulum impact test rig was designed and used to test the prototypes. The test results and analytical values were shown to be satisfactorily close to each other.