Hughes Aircraft Company

Hughes Electronics Corporation

United States of America As Represented by the Secretary of the Air Force

Other

Howard H Rogers

Steven J Stadnick

Richard P Sernka

Hong S Lim

Scott A Verzwyvelt

Preston S DuPont

Jerry J Herrin

A 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 open-circuit failure of the electrical storage cell. The bypass circuit path includes a first electrical conductor connected to the positive terminal of the electrical storage cell, a second electrical conductor connected to the negative terminal of the electrical storage cell, and a shorting gap between the first electrical conductor and the second electrical conductor. A mass of a fusible material is positioned at an initial mass location. A heat source is activatable upon the occurrence of an open-circuit condition of the electrical storage cell. The heat source is operable to melt at least a portion of the mass of the fusible material and thereby to close the shorting gap so that the first electrical conductor is in electrical communication with the second electrical conductor.

Low-voltage-drop bypass of failed battery cell

A 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 open-circuit failure of the electrical storage cell. The bypass circuit path includes a first electrical conductor connected to the positive terminal of the electrical storage cell, a second electrical conductor connected to the negative terminal of the electrical storage cell, and a shorting gap between the first electrical conductor and the second electrical conductor. A mass of a fusible material is positioned at an initial mass location. A spring is positioned to force the mass of the fusible material from the initial mass location, along the metal flow path, and into the shorting gap, when the mass of the fusible material is at least partially molten. A heat source is activatable upon the occurrence of an open-circuit condition of the electrical storage cell. The heat source is operable to melt at least a portion of the mass of the fusible material. The spring forces the molten material into the shorting gap, where it solidifies and closes the shorting gap so that the first electrical conductor is in electrical communication with the second electrical conductor.

Low-voltage-drop, spring-activated bypass of failed battery cell

A 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 open-circuit failure of the electrical storage cell. The bypass circuit path includes a normally open bypass circuit path comprising a diode having a cathode and an anode. The cathode of the diode is electrically connected to the positive terminal of the electrical storage cell and the anode of the diode is electrically connected to the negative terminal of the electrical storage cell. The diode fails to a shorted current path at an imposed current less than a cell failure current, providing a low-resistance, low-voltage-drop bypass of the electrical storage cell.

Low-voltage-drop diode bypass of failed battery cell

A nickel-hydrogen energy storage cell includes a hermetic pressure vessel having a wall made of a nickel-base alloy, and a hollow tube made at least in part of palladium and joined to the wall of the pressure vessel such that an interior of the hollow tube is in communication with an interior of the pressure vessel. A heater controllably heats at least a portion of the hollow tube to increase the diffusion rate of hydrogen through the wall of the hollow tube and thereby controllably vent hydrogen from the pressure vessel. The energy storage cell further includes at least one plate set within the wall of the pressure vessel, an electrolyte, and a pair of electrical leads extending from the at least one plate set and through an electrical feedthrough in the wall of the pressure vessel.

Energy storage cell with hydrogen vent

A group of electrically interconnected energy storage cells, such as nickel-hydrogen energy storage cells, is pressure balanced and its precharge reset by discharging the energy storage cells of the group to a substantially fully discharged state, venting all of the energy storage cells of the group to the same reduced internal hydrogen pressure, and thereafter discontinuing the venting. The venting occurs without recharging the energy storage cells, and after venting is complete the energy storage cells of the group are recharged.

Resetting the precharge of a group of pressurized gas energy storage

A multicell battery system includes at least two battery cells, and a selective cell bypass for each of the battery cells. Each cell bypass includes a metal-oxide-semiconductor field effect transistor (MOSFET) having a source, a drain, and a gate, a first electrical interconnection from the MOSFET source to a first side of the battery cell, a second electrical interconnection from the MOSFET drain to a second side of the battery cell, and an activation circuit connected to the MOSFET gate. The activation circuit includes an AND gate having as one input an AC square wave signal and as a second input a selection signal, a capacitor connected to the AND gate output signal, and a cascade voltage doubling circuit having an input in communication with a second electrode of the capacitor and an output in communication with the MOSFET gate.

Multicell battery system with individually controllable cell bypasses

Improved nickel-hydrogen batteries (10) are disclosed, wherein the improvement provides for wettable porous polypropylene cloth gas diffusion screens (12) to separate the individual cells (16) thereof. When necessary, substantially all of the electrolyte may be readily drained from the cells (16) of the batteries (10). Wettability is achieved by oxidizing the surfaces of the cloth gas diffusion screens (12) prior to assembling them in the batteries (10).

Nickel-hydrogen cells

A deformable element is placed between the active plate sets of a storage battery to accommodate, by permanent compressive deformation, the swelling that occurs in the positive electrode of the plate set during extended cycling of the storage battery. The plate sets are normally supported on a core under axial compressive loading, and the swelling would otherwise deform or place a strain on the electrode connector leads, which could cause them to fail by shorting. The deformable element, preferably a modified polypropylene screen that permits the release of gas from the electrode and also is deformable in the direction perpendicular to the screen, compressively deforms to absorb the gradually increasing swelling of the positive electrode. The loading on the electrode connectors is thereby avoided or minimized, removing a major potential cause of failure.

Battery cell stack having extended life

A relay (30) has one or both current carrying relay contacts (12, 14) made of a soft, deformable, readily fusible metal, preferably indium, lead, cadmium, bismuth, or tin. When the relay (30) closes, the contacts (12, 14) deform or fuse together, ensuring good electrical conductance and eliminating chatter and accidental opening. The relay (30) is particularly useful in a bypass circuit (54) for a spacecraft battery system (50).

One-time-close relay useful in spacecraft power systems

The conventional sintered, thin hydrogen negative electrode of a nickel-hydrogen storage cell or the like is replaced by a thicker porous electrode having a greater volume to receive water produced at the negative electrode during discharge of the cell. As a result, the dilution of the electrolyte within the negative electrode is less as compared with the thinner electrode, so that the freezing point depression of the electrolyte within the negative electrode is maintained. Freezing of the electrolyte and reduced performance of the cell are thereby avoided. To maintain the low weight of the electrode and reduce its cost even though its thickness is increased, platinum particles are replaced by conductive particles upon which platinum has been deposited.

Electrical storage cell resistant to freezing

A sodium sulfur electrical storage cell includes means for avoiding bubbles in the sulfur cathode during operation in a weightless environment. Formation of bubbles of sulfur or other gas in the cathode is prevented by pressurizing the sulfur cathode to a pressure greater than the vapor pressure of the sulfur at the operating temperature, typically about 350 C. The applied pressure is preferably supplied by a chemical compound, such as sodium azide, that is placed into the chamber holding the sulfur. At the operating temperature of the cell, the compound decomposes to produce a gas, nitrogen in the case of the sodium azide, that is substantially insoluble in the sulfur yet produces a sufficiently high pressure over the liquid sulfur that bubbles of gaseous sulfur or other gases cannot form in the sulfur. If bubbles were permitted to form in a weightless environment, they would migrate to a location where they would interfere with the operation of the cell.

Sodium sulfur cell for weightless environments

A process and apparatus for controlling the charging of pressurized gas-metal cells such as nickel-hydrogen cells, to prevent detrimental overcharging, wherein the time rate of change of a battery gas pressure index is monitored as a control parameter. When the time rate of change of the index falls below a preselected value, charging is discontinued. The cell gas pressure index can be gas pressure itself, or a quantity which is responsive to, and depends upon gas pressure, such as the deformation of a cell component.

Control of the charging of pressurized gas-metal electrical storage cells

A process for preventing electrical capacity loss during storage of a pressurized nickel-hydrogen electrical storage cell. An electrical precharge is applied to the positive electrode of the cell, so that discharge of the cell is negative electrode limited. In one approach, the cell is charged, while sealed, to a state of charge corresponding to a first gas pressure, and then the hydrogen pressure is reduced to a lower value, preferably about atmospheric. In another approach, a current is passed through the cell while the cell is unsealed and maintained at atmospheric gas pressure, until the cell reaches the desired state of charge.

Process for preventing electrical storage cell capacity loss

A process is provided for removing contaminating residues left behind during fabrication of gas electrodes employed in metal/gas batteries, e.g., nickel/hydrogen batteries, and fuel cells employing gas electrodes. Such residues arise from depositing and sintering on a conductive, screen-type electrode substrate a platinum powder/polytetrafluoroethylene powder mixture containing a suspending agent. The residues of the suspending agent are removed by contacting the fabricated electrode with a solvent mixture comprising a first solvent, e.g., trichloroethylene, for dissolving the residues and a second solvent, e.g., ethanol, for wetting the polytetrafluoroethylene.

Process for removing residues from gas electrodes

High energy alkaline storage batteries exhibiting exceptionally long storage life are fabricated from cells which show no sign of deterioration after more than 3000 cycles at 80% depth of discharge. The exceptional characteristics of these cells are attributed to improved separators fabricated from zirconium oxide cloth reinforced with organic polymeric materials.

Growing community of inventors

Torrance, CA, United States of America

Howard H Rogers