Space Systems/loral, LLC

Stephen J Lenhart

John C Hall

Michael J McVey

Carl R Halbach

Anthony Z Applewhite

Catherine L English

Rebecca R Chang

A battery cell bypass module comprises a sensor for detecting an operating condition of a battery cell such as voltage or temperature and a controller connected across the battery cell of a lithium ion battery, for example, and having a conductive mode and a normally non conductive mode. The controller is operable to change to the conductive mode when an operating condition of the battery cell exceeds a predetermined value to thereby shunt current around the battery cell. The sensor may be a temperature transducer such as a thermistor for measuring battery cell temperature and a cell temperature comparator such as an operational amplifier is operable to generate a temperature excessive signal when the signal from the temperature transducer exceeds a predetermined value, the controller then being operable to change to the conductive mode and thereby shunt current around the battery cell. The sensor may also be a voltage comparator, also an operational amplifier, for measuring voltage across the cell, the controller being operable in response to a voltage excessive signal to change the controller to the conductive mode and thereby shunt current around the battery cell. The controller includes a voltage limiting operational amplifier operable for transmitting a voltage excessive output signal when the input thereto exceeds a predetermined value and a transistor having a predetermined gate voltage allowing bypass current flow, the transistor being responsive to the voltage excessive output signal from the voltage limiting operational amplifier to shunt current around the battery cell.

Battery cell bypass module

A technique of operating a lithium-ion (Li-ion) battery is proposed for maximizing battery life. In a first instance, this technique calls for charging the battery at a lower temperature than the temperature at which discharge begins. Preferably, the battery is charged at a temperature T.sub.1 in the range between about +5.degree. C. and -20.degree. C.; and discharged at a temperature T.sub.2, in the range of about +5.degree. C. to +30.degree. C., T.sub.2 being higher than T.sub.1. In another instance proposed by the invention, the battery is charged to an elevated state of charge which is above an initial state of charge at a temperature T.sub.1 between about +5.degree. C. and -20.degree. C. which is lower than a temperature T.sub.2, in the range of about +5.degree. C. to +30.degree. C., at which discharge begins. In still another instance proposed by the invention, after the battery has been charged and discharged during the eclipse season, it is then charged to an intermediate charge level between about 40% and about 60% state of charge over a relatively long lapsed duration of time, about one month to about six months, and thereafter, the battery is maintained at this intermediate charge level.

Lithium-ion battery charge control method

A bipolar rechargeable battery comprises a vessel with an insulated liner and an interior region for bulk storage of a gas which serves as an electrode active material. A plurality of cells are nested within the vessel, each including a metallic bipolar cup having a circular base and an integral insulated hydrophobic upstanding side wall of truncated conical shape diverging with increased distance from the base. A positive electrode overlies the base. A dielectric separator separates the positive electrode and a negative electrode sized to fittingly engage the side wall such that any gas generated at the positive electrode must pass through the negative electrode to escape the cell to thereby recombine the generated gas with the active material gas within the cell. The upstanding side wall of each cell is oriented to enable gas passage from each of said cells to the bulk gas storage region. The upstanding side walls of the adjacent cells mutually define a gap enabling gas communication between the adjacent cells and between each of the cells and the bulk gas storage region. A gas screen of porous conductive inert material may overlie the gas electrode, providing an interface between the cell and an adjoining cell in the battery and passage of gas between the bulk gas storage and the gas electrode current collector.

Bipolar cell design for a gas depolarized battery

An improved method of charging a rechargeable nickel/hydrogen battery comprises the steps of applying a charging current to the battery resulting in a substantially full state of charge, then for a period up to approximately 60 minutes before the onset of discharging, applying a boost charging current at a rate in the range of approximately C to C/20 for a duration up to approximately 60 minutes. The charging of the battery before applying the boost step may include the application of a taper charging current. Also, at the end of the taper charging step and immediately prior to the boost charge, a trickle charging current may be applied at a rate in the range of approximately C/80 to C/500. In another instance, when the battery has been charged to about 70% to 95% of a full state of charge, the linearly decreasing taper charge may be applied until a final desired recharge ratio is reached. Thereafter, up to a duration of approximately 60 minutes before the onset of discharging, the boost charging current may be applied at a rate in the range of approximately C to C/20 for part of or for the entire duration. The timed sequence of the initial high rate charge, the taper charge, the trickle charge, and the boost charge, in conjunction with proper control of battery temperature and recharge ratio has been found to increase overall battery capacity by approximately 10% to 30%.

Recharge profile for spacecraft NI/H.sub.2 batteries

A method for making a battery electrode includes roughening the surface of a substrate (10) that constitutes a precursor to the electrode, using an electrolytic solution (12) with electrical potential perturbations applied thereto. The substrate (10) of porous sintered nickel powder is first formed. The electrolytic solution (12) prefereably contains the pure metal that forms the electrode. Then all gases in and around the substrate (10) are preferably removed. Next, the substrate (10) is placed in the solution (12) for a predetermined amount of time. Potential perturbations are then applied to the substrate (10) and the solution (12). The potential peturbations vary between the voltages necessary for electrodissolution and electrodepositon of the substrate (10), and thus, cause the surface of the substrate (10) to be roughened as portions of the substrate (10) are dissolved into the solution (12) and then redeposited onto the substrate's (10) surface. Once roughened, the plaque (14) is removed from the solution (12) and any remaining solution is rinsed off the roughened plaque (14).

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Mountain View, CA, United States of America

Stephen J Lenhart