1、Best Practices Entry: Best Practice Info:a71 Committee Approval Date: 2000-03-15a71 Center Point of Contact: GSFCa71 Submitted by: Wil HarkinsSubject: Nickel-Hydrogen Spacecraft Battery Handling and Storage Practice Practice: Develop and implement handling and storage procedures to ensure reliable o
2、peration, minimize deterioration, and prevent irreversible effects on the flight performance of Ni-H2flight batteries due to improper handling and storage.Programs that Certify Usage: This practice has been used on Hubble Space Telescope (HST) (NASAs first flight use of Ni-H2batteries in a low Earth
3、 orbit application); Earth Observing System AM, (EOS AM), LANDSATCenter to Contact for Information: GSFCImplementation Method: This Lessons Learned is based on Reliability Practice No. PD-ED-1109; from NASA Technical Memorandum 4322A, NASA Reliability Preferred Practices for Design and Test.Benefit:
4、Nickel-Hydrogen (Ni-H2) batteries will significantly deteriorate, principally due to capacity fading, if the proper storage and handling procedures are not followed in a number of stages in the cell/battery lifetime. A set of proven guidelines is followed by flight projects in the preparation and ut
5、ilization of project unique handling and storage procedures in order to minimize these deterioration effects and Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ensure the reliable performance of Ni-H2batteries.Implementation Method:A sealed Ni-H2sec
6、ondary cell is a hybrid, combining battery and fuel-cell technologies. The nickel positive electrode comes from the nickel-cadmium cell and the negative platinum electrode from the hydrogen-oxygen fuel cell. The cell is contained in a pressure vessel designed to operate up to 1,200 p.s.i. of hydroge
7、n gas when the cell is fully charged. Pressure measurements can be used to determine the “state of charge“ of batteries in flight. Salient features of the Ni-H2battery are a long cycle life that exceeds any other maintenance-free secondary battery system, high specific energy (gravimetic energy dens
8、ity), high power density (pulse or peak power capability), and a tolerance to overcharge and reversal. It is these features that make the Ni-H2battery system the prime candidate for the energy storage subsystem in many aerospace applications, such as geosychronous-earth-orbit (GEO), commercial commu
9、nications satellites, and low-earth-orbit (LEO) satellites. The GEO and the LEO applications have two different requirements for batteries. The LEO applications require charge/discharge cycles of 18,000 to 30,000 cycles with depth of discharges (DOD) up to 40% and up to a 5 year lifetime in orbit. T
10、he GEO applications require lifetimes in orbit of 5 to 10 years and about 100 cycles per year with maximum DODs of 60% for a total of 500 to 1,000 cycles. To meet these mission requirements, a number of different design approaches are used by a variety of Ni-H2battery manufacturers.Generally, two or
11、 more batteries are used per spacecraft to meet the power requirements. The major advantage of using multiple batteries is reliability. If one battery fails, the other battery or batteries can maintain all or at least the most significant functions of the spacecraft.The storage and handling of Ni-H2
12、cells and batteries can significantly alter performance during both prelaunch and mission lifetimes. The development of a low-voltage plateau in the discharge mode or capacity fading (loss of capacity to 1.0 volts) is the major concern. Under most circumstances, capacity can be recovered. However, i
13、f a cell or battery is overheated, it can be permanently damaged. The following storage and handling procedures cover the three stages in the cell/battery lifetime:Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Stage 1 - Storage of cells after manuf
14、acture and before assembly into batteries:Storage periods can range from a few weeks to several years depending upon the launch schedule. The following three methods are used to store and maintain capacity of cells for periods of time from several weeks up to three years. a. Store fully charged cell
15、s open-circuited at temperatures below 0C. These cells must be recharged, (topped off), every 7 to 14 days.b. Store fully charged cells at temperatures below 0C with a trickle charge rate of C/100.c. Store discharged cells open-circuited at 0C for up to three years.Stage 2 - Storage of batteries aft
16、er assembly:Once the flight batteries are assembled, they are generally stored until they are shipped to the launch site for integration into the spacecraft. For flight batteries, the storage period can range from a few months to three years. The longer periods represent program delays that affect l
17、aunch schedules. The same methods for the storage of batteries can be used as defined above for cells. Regardless of the method of storage used, the capacity of batteries is measured both before and after storage to determine if any capacity fading has occurred during storage.Stage 3 - Storage of ce
18、lls/batteries during shipment:Cells/batteries are fully discharged and short circuited during shipment. Each cell/battery is wrapped separately with its own packaging material to exclude humidity and control temperatures to 5C (+/- 5C). Five to 10 cells can be packed within the same container and sh
19、ipped air express to minimize shipping time. The shipping container should be equipped with temperature recorders to provide assurance that flight cells/batteries have not been exposed to temperatures exceeding 25C. The capacity of cells/batteries is measured both before and after shipment to determ
20、ine if any capacity fading has occurred during shipping.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Stage 4 - Storage of batteries at the launch site:Batteries should be in the fully discharged state during handling operations at the launch site.
21、 Batteries can then be maintained during short term storage in the charged state at room temperatures but must be recharged every 7 to 14 days. Also, flight batteries can be maintained on trickle charge prior to launch. The final reconditioning of flight batteries should be performed 14 days prior t
22、o spacecraft launch. Upon completion of the reconditioning, flight batteries should be kept on low rate trickle charge until launch or reconditioned every 30 days if the launch is delayed. The batteries should be kept in cold storage if the launch is delayed beyond 90 days.The following additional g
23、eneral guidelines and procedures are used in the handling and operation of Ni-H2batteries.1. A battery should be “reconditioned“ if it has been on open circuit, subjected to intermittent use, i.e., open circuit, trickle charge, occasional discharge, etc., for a cumulative period of 30 days. Recondit
24、ioning is effected by performing the following sequence at 20C. a. Discharge at C/2 constant current rate until the first cell reaches 1.0 v/c.b. Drain each cell with a 1 ohm resistor until each cells voltage is less than .03 V/C.c. Recharge battery at C/20 constant current rate for 40 hours (+/- 4
25、hours).d. Repeat steps a and b.e. Charge battery at C/10 constant current rate for 16 hours ( +/- 4 hours).f. Repeat steps a, b, and e.2. 3. Batteries are not charged or discharged in parallel. Isolation is provided in spacecraft power systems to ensure that a failure of one battery does not affect
26、another battery.4. 5. Batteries are charged and all functions and cells are checked out thoroughly prior to installation in a flight spacecraft. Batteries are installed into a spacecraft in a discharged state.6. 7. “Tap“s are never installed on any portion of a string of cells in series that can cau
27、se unbalanced loading of portions of a battery.8. 9. Shorting resistors are normally placed across individual cells to prevent cell reversal which Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-could damage individual cells when flight Ni-H2batterie
28、s are stored short circuited.10. 11. Power system designs include circuitry to prevent overcharging of batteries and the generation of excessive heat which can damage batteries.12. 13. The temperatures of Ni-H2batteries are monitored during operation and storage. Operating temperatures are not permi
29、tted beyond 18C and non-operating exposures are not permitted beyond 25C. Exposure to temperatures beyond 30C results in permanent loss of capacity.14. 15. Heaters are used as required to insure that the temperature of Ni-H2batteries do not go below -25C at any time in order to prevent freezing of t
30、he electrolyte.16. 17. Flight batteries should not be subjected to extended spacecraft integration and test activities. The open circuit and intermittent use of Ni-H2batteries during extended spacecraft integration and testing activities are known to significantly accelerate the degradation of batte
31、ries. Results from controlled tests have shown permanent and irreversible changes.18. 19. The design of flight batteries should include the following provisions for ground console interfacing with the batteries while integrated into the spacecraft. a. Signal lines for monitoring total battery voltag
32、e, charge and discharge currents, battery temperatures, and individual cell voltages.b. Capabilities to charge and discharge the battery from the ground test console.c. Capability to place a resister and a shorting plug across each individual cell.20. 21. A log book shall be maintained on each fligh
33、t battery including the complete test histories of each cell, of the assembled battery, and of all integration and test and launch site activities. Each log book shall identify the project and battery and individual cell serial numbers. Chronological (date and time) entries for all test sequences, s
34、ummary of observations, identifications of related computer stored records, malfunctions, names of responsible test personnel, and references to test procedures controlling all tests shall be recorded.Since Ni-H2batteries are perishable, their ability to satisfactorily complete their mission life is
35、 directly related to their storage, their ground use, and handling. Historical performance information is required to ensure their flight worthiness at launch time.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Technical Rationale:Ni-H2batteries can
36、 deteriorate due to improper storage and handling. This practice which avoids this deterioration is based on a long period of battery development, testing, and flight experience.References:1. NASA Handbook for Nickel-Hydrogen Batteries: NASA Reference Publication 1314, September 1993Impact of Non-Pr
37、actice: The impact of not following this practice is that batteries may be damaged during handling and storage and may exhibit degraded performance during the mission including early life failure. Additionally, batteries may not be properly charged prior to launch and therefore may not meet their mi
38、ssion performance requirements or may require a lengthy recharging procedure before the satellite can be fully activated.Related Practices: N/AAdditional Info: Approval Info: a71 Approval Date: 2000-03-15a71 Approval Name: Eric Raynora71 Approval Organization: QSa71 Approval Phone Number: 202-358-4738Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
