Engineering topics

Rao, Gopalakrishna M.

Publications and source records attributed to Rao, Gopalakrishna M..

At least 37 records · Page 2

NASA NTRS2001

Crane Cell Testing Support of NASA/Goddard Space Flight Center: An Update

The objectives presented in this viewgraph presentation include: 1) Verify the quality and reliability of aerospace battery cells and batteries for NASA flight programs; 2) Disseminate the data to develop a plan for in-orbit battery management and to design a cell/battery for future NASA spacecraft; and 3) Establish a cell test data base for rechargeable cell/batteries. In summary: quality EPT Ni-H2, EPT Super NiCd and SAFT NiCd cells have been demonstrated for aerospace applications; the data has been provided to NASA Centers and other agencies for their use and application; developed plan and used in NASA in-orbit battery management. Database on rechargeable cell/batteries is now available for customer use.

Strawn, Mike↗

NASA NTRS2001

NASA/GSFC Testing of Li-Ion Cells: Update

This viewgraph paper presents a report on the ongoing testing of Lithium Ion (Li-Ion) cells. Characterizes cells according to capacity, self-discharge, and mid-discharge voltage. Determines the cycling performance of Li-Ion cells as batteries according to number of cycles, charge voltage, and temperature.

Vaidyanathan, Hari↗

NASA NTRS2001

Crane Cell Testing Support of Nasa/goddard Space Flight Center: an Update

The objective of this paper is to verify the quality and reliability of aerospace battery cells and batteries for NASA flight programs, disseminate the data - to develop a plan for in-orbit battery management - to design a cell/battery for future NASA spacecraft and establish a cell test data base for rechargeable cell/batteries.

Strawn, Mike↗

NASA NTRS2001

Development of a 10 Ah, Prismatic, Lithium-Ion Cell for NASA/GSFC

MSA's 10 Ah Li-ion cell is a rugged design suitable for the stringent requirements of aerospace applications. Eighteen cells demonstrate consistent cycling performance over a wide range of rates and temperatures. The cell passes qualification requirements for vibration survivability technology improvements at MSA continue to enhance cell performance.

Stein, Brian↗

NASA NTRS2001

AEA Technologies Battery Cell By-pass Device Activation: An Update

The objectives are to: (1) Verify the Performance of AEA Cell Bypass Protection Device (CBPD) under simulated EOS-Aqua/Aura flight hardware configuration; (2) Assess the Safety of the hardware under an inadvertent firing of CBPD switch, as well as the closing of CBPD switch under simulated high cell impedance; and (3) Confirm that the mode of operation of CBPD switch is the formation of a continuous low impedance path (a homogeneous low melting point alloy).

Keys, Denney↗

NASA NTRS2000

Effects of AEA Cell-Bypass-Switch Closure on Charged EOS-Aqua NiH2 Cell

A viewgraph presentation outlines the effects of AEA cell bypass-switch closure on a charged EOS-Aqua NiH2 cell. The objectives of the presentation are to: (1) Verify the Performance of AEA Cell Bypass Protection Device (CBPD) under simulated EOS-Aqua/Aura flight hardware configuration; (2) Assess the safety of the hardware under an inadvertent firing of CBPD switch, as well as the closing of CBPD switch under simulated high cell impedance; and (3) Confirm that the mode of operation of CBPD switch is the formation of a continuous low impedance path-homogeneous low melting point eutectic (Indium alloy). Details are given on the EOS-Aqua flight hardware, AEA hardware tested, AEA bypass switch schematic, and the tests performed, which include images of equipment and results.

Keys, Denney↗

NASA NTRS2000

Effect of Handling, Storage and Cycling on Ni-H2 Cells: Second Plateau Phenomenon

A viewgraph presentation outlines the effects of handling, storing, and cycling of NiH2 cells, particularly the second plateau phenomenon. Details are given on the criteria for cell selection, cell history, the second plateau capacity at C/2 discharge, and cell reversal test conditions. Tables display a gas analysis and nickel precharge.

Vaidyanathan, Hari↗

NASA NTRS2000

NASA/GSFC Testing of Li-ion Cells: Update

A viewgraph presentation outlines: (1) cell characteristics, including capacity, self-discharge, and mid-discharge voltage; and (2) a determination of cycling performance as a battery pack, including details on number of cycles, charge voltage, and temperature, for prismatic cells (20 AH Yardney and 1.5 AH Wilson Greatbatch), cylindrical cells (12 AH, 4 AH, and 1.25 AH SAFT), and polymer cells (3 AH Alliant Tech and 8 AH Lithium Technology, Inc.).

Vaidyanathan, Hari↗

NASA NTRS1999

Design and Flight Performance of NOAA-K Spacecraft Batteries

The US National Oceanic and Atmospheric Administration (NOAA) operates the Polar Operational Environmental Satellite (POES) spacecraft (among others) to support weather forecasting, severe storm tracking, and meteorological research by the National Weather Service (NWS). The latest in the POES series of spacecraft, named as NOAA-KLMNN, is in orbit and four more are in various phases of development. The NOAA-K spacecraft was launched on May 13, 1998. Each of these spacecraft carry three Nickel-Cadmium batteries designed and manufactured by Lockheed Martin. The battery, which consists of seventeen 40 Ah cells manufactured by SAFT, provides the spacecraft power during the ascent phase, orbital eclipse and when the power demand is in excess of the solar array capability. The NOAA-K satellite is in a 98 degree inclination, 7:30AM ascending node orbit. In this orbit the satellite experiences earth occultation only 25% of the year. This paper provides a brief overview of the power subsystem, followed by the battery design and qualification, the cell life cycle test data, and the performance during launch and in orbit.

Rao, Gopalakrishna M.↗

NASA NTRS1999

Performance of Nickel-Cadmium Batteries on the GOES-1 Series of Weather Satellites

This is an errata from an original paper published in the 1997 NASA Aerospace Battery workshop proceedings. A minor change was made to the second equation on page 98 and table 4 was revised during the final preparation of the paper. These changes were inadvertently left out of the final proceedings. These pages are reproduced in their entirety.

Singhal, Sat P.↗

NASA NTRS1999

Design and Performance of Tropical Rainfall Measuring Mission (TRMM) Super NiCd Batteries

The Tropical Rainfall Measuring Mission (TRMM) is a joint mission between NASA and the National Space Development Agency (NASDA) of Japan. The observatory is designed to monitor and study tropical rainfall and the associated release of energy that helps to power the global atmospheric circulation shaping both weather and climate around the globe. The spacecraft was launched from Japan on November 27,1997 via the NASDA H-2 launch vehicle. The TRMM Power Subsystem is a Peak Power Tracking system that can support the maximum TRMM load of 815 watts at the end of its three year life. The Power Subsystem consists of two 50 Ampere Hour Super NiCd batteries, Gallium Arsenide Solar Array and the Power System Electronics. This paper describes the TRMM Power Subsystem, battery design, cell and battery ground test performance, and in-orbit battery operations and performance.

Ahmad, Anisa J.↗

NASA NTRS1999

Nickel-Hydrogen Cell Testing Experience, NASA/Goddard Space Flight Center

The objectives of the project were to test the Nickel-Hydrogen Cell to: (1) verify the Aerospace Cell Flight Worthiness, (2) Elucidate the Aerospace Cell Thermal Behavior, (3) Develop the Aerospace Battery Assembly Design(s) and In-orbit Battery Management plan(s) and (4) Understand the Aerospace Cell Failure Mechanism. The tests included the LEO and GEO Life cycle tests, Calorimetric Analysis, Destructive Physical analysis, and special tests. Charts show the Mission Profile Cycling Data, Stress Cycling Data. The test data complies with the mission requirements, validating the flight worthiness of batteries. The nominal stress and mission profile cycling performance test shows the charge voltage as high as 1.60V and recharge ratio greater than 1.05. It is apparent that the electrochemical signatures alone do not provide conclusive proof for Nickel precharge. The researchers recommend a gas and positive plate analyses for further confirmation.

Rao, Gopalakrishna M.↗

NASA NTRS1999

The Effect of Cathode Composition on the Thermal Characteristics of Lithium-Ion Cells

The specific thermal capacity and heat dissipation rate for lithium ion cells containing LiNiO2 and mixed oxide (75%LiCoO2+ 25%LiNiO2) as cathode materials are compared. The experimental measurements were made using a radiative calorimeter consisting of a copper chamber maintained at -168 C by circulating liquid nitrogen and enclosed in a vacuum bell jar. The specific thermal capacity was determined based on warm-up and cool-down transients. The heat dissipation rate was calculated from the values measured for heat radiated and stored, and the resulting values were corrected for conductive heat dissipation through the leads. The specific heat was 1.117 J/ C-g for the LiNiO2 cell and 0.946 J/ C-g for the 75%LiCoO2,25%LiNiO2 cell. Endothermic cooling at the beginning of charge was very apparent for the cell containing 75%LiCoO2,25%LiNiO2 as the cathode. Exothermic heating began at a higher state of charge for the cell with the 75%LiCoO2,25%LiNiO2 cathode compared to the LiNiO2 cathode cell. During discharge, the rate of heat dissipation increased with increase in the discharge current for both types of cells. The maximum heat dissipated at C/5 discharge was 0.065 W and 0.04 W for the LiNiO2 and 75%LiCoO2,25%LiNiO2 cells, respectively, The thermoneutral potential showed variability toward the end of discharge. The plateau region of the curves was used to calculate average thermoneutral potentials of 3.698 V and 3.837 V for the LiNiO2 cell and the 75%LiCoO2,25%LiNiO2 cell, respectively.

Vaidyanathan, Hari↗

NASA NTRS1998

Performance of Nickel-Cadmium Batteries on the GOES 1-K Series of Weather Satellites

The US National Oceanic and Atmospheric Administration (NOAA) operates the Geostationary Operational Environmental Satellite (GOES) spacecraft (among others) to support weather forecasting, severe storm tracking, and meteorological research by the National Weather Service (NWS). The latest in the GOES series consists of five spacecraft (originally named GOES 1-M), three of which are in orbit and and two more in development. Each of the five spacecraft carries two Nickel-Cadmium battery, with batteries designed by Space Systems Loral (SS/L) and cells manufactured by Gates Aerospace Batteries (sold to SAFT in 1993). The battery, which consists of 28 cells with a 12 Ah capacity, provides the spacecraft power needs during the ascent phase and during the semi-annual eclipse seasons lasting for approximately 45 days each. The maximum duration eclipses are 72 minutes long which result in a 60 percent depth of discharge (DOD) of the batteries. This paper provides a description of the batteries, reconditioning setup, DOD profile during a typical eclipse season, and flight performance from the three launched spacecraft (now GOES 8, 9, and 10) in orbit.

Singhal, Sat P.↗

NASA NTRS1998

Performance of Nickel-Cadmium Batteries on the POES Series of Weather Satellites

The advanced Television Infrared Observation satellite program is a cooperative effort between the National Aeronautics and Space Administration (NASA), the National Oceanic and Atmospheric Administration (NOAA), the United Kingdom, Canada and France, for providing day and night global environmental and associated data. NASA is responsible for procurement launch, and checkout of these spacecraft before transferring them over to NOAA, who operates the spacecraft to support weather forecasting, severe storm tracking, and 'meteorological research by the National Weather Service. These spacecraft with all weather monitoring instruments imposed challenging requirements for the onboard electrical power subsystem (EPS). This paper provides first a brief overview of the overall power subsystem, followed by a description of batteries. A unique power subsystem design which provides 'tender-loving-care' to these batteries is highlighted. This is followed by the on-orbit maintenance and performance data of the batteries since launch.

Rao, Gopalakrishna M.↗

NASA NTRS1998

Design and Flight Performance of NOAA-K Spacecraft Batteries

The US National Oceanic and Atmospheric Administration (NOAA) operates the Polar Operational Environmental Satellite (POES) spacecraft (among others) to support weather forecasting, severe storm tracking, and meteorological research by the National Weather Service (NWS). The latest in the POES series of spacecraft, named as NOAA-KLMNN', one is in orbit and four more are in various phases of development. The NOAA-K spacecraft was launched on May 13, 1998. Each of these spacecraft carry three Nickel-Cadmium batteries designed and manufactured by Lockheed Martin. The battery, which consists of seventeen 40 Ah cells manufactured by SAFT, provides the spacecraft power during the ascent phase, orbital eclipse and when the power demand is in excess of the solar array capability. The NOAA-K satellite is in a 98 degree inclination, 7:30AM ascending node orbit. In this orbit the satellite experiences earth occultation only 25% of the year. This paper provides a brief overview of the power subsystem, followed by the battery design and qualification, the cell life cycle test data, and the performance during launch and in orbit.

Rao, Gopalakrishna M.↗

NASA NTRS1997

On-Orbit Health Check of Hubble Space Telescope Nickel-Hydrogen Batteries

The Hubble Space Telescope is a one-of-a-kind spacecraft that pushes technology to its limits. Housing an 8-foot (2.4 meter) mirror and several sophisticated cameras and detectors the telescope is the largest orbital astronomy observatory ever placed in space. It has two modules each containing three 88 Ah NiH2 batteries (six total). Reconditioning has traditionally been used as a means of maintaining the performance of normal cells and batteries. This paper describes the objective, procedure, and results of a reconditioning processes that used to improve the performance of an HST nickel-hydrogen batteries.

Rao, Gopalakrishna M.↗

NASA NTRS1997

Effect of Storage on Performance of Super Nickel-Cadmium Cells

A study was undertaken to examine the capacity maintenance features of SUPER nickel-cadmium cells when stored for extended periods to determine whether the features change when the same kinds of positive plates as that used in nickel-hydrogen cells are used, The cells maintained their capacity when stored at 0 C in the discharged state and at 0 C in the charged state by continuously trickle charging. There was a capacity loss when stored in the open-circuit condition at 28 C. A cycling test at 17% depth of discharge for 2400 cycles using cells stored at various conditions showed that cells maintained good end of discharge voltage regardless of their storage history. However, the EOD voltages of stored cells were lower by 10 mV compared to those of fresh cells. The capacity at the end of the cycling test decreased for the stored cells by 2-7 Ah. The storage related capacity loss is lower for SUPER Ni-Cd cells compared to that of Ni-H2 cells containing a hydrogen precharge. The results suggest the pivotal role of hydrogen pressure in the capacity loss phenomenon.

Vaidyanathan, Hari↗