Low energy activation fault tolerant battery cell bypass device and system

Abstract

A low energy activation, fault tolerant, battery system includes an electrical storage cell having a positive terminal and a negative terminal. The electrical storage cell is provided with a normally open bypass circuit path that is closed in the event of an overdischarged, or open-circuit failure of, the electrical storage cell. The bypass circuit path includes a first electrical conductor connected to the negative terminal of the electrical storage cell, a second electrical conductor connected to the positive terminal of the electrical storage cell, and a shorting gap between the first electrical conductor and the second electrical conductor. The first and second electrical conductors and a non-conductive carrier at least partially enclose a heat source activatable upon the occurrence of the failed cell, a mass of a meltable material that is heated by the heat source, a plunger having an electrically conductive face, and a spring that is positioned to force the plunger into the mass of the meltable material when it is at least partially molten. The heat source includes two diodes connected in electrical series, each of which is operable to melt at least a portion of the mass of the meltable material. When the spring forces the plunger into the meltable material, the electrically conductive face of the plunger head physically contacts the first and second electrical conductors to eliminate the shorting gap so that the first electrical conductor is in electrical communication with the second electrical conductor.