ALBERT

Description: This viewgraph presentation reviews the issues concerning storage of lithium ion batteries. The presentation outlines tests used to establish a best long term storage for the lithium ion cells. Another objective of the study was to determine the preferred solstice condition for the lithium ion chemistry (polymer and liquid electrolyte). It also compared voltage clamped with trickle charge storage. The tests and results are reviewed

Description: A viewgraph presentation outlines the Earth Radiation Budget Satellite (ERBS) power system and battery history. ERBS spacecraft and battery cell failures are listed with the reasons for failure. The battery management decision and stabilization of the batteries is discussed. Present battery operations are shown to be successful.

Description: 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.

Description: The nominal performance of AEA CBPD under simulated EOS-Aqua/Aura flight hardware configuration has been demonstrated. There is no evidence of cell rupture or excessive heat production during or after CBPD switch activation under simulated high cell impedance (open-circuit cell failure mode). Inadvertent CBPD switch activation with a charged cell (low impedance path) intermittently closes and opens up the switch, therefore the device may or may not provide protection against future open-circuit cell failure. Further testing with switches F01 and F02 may provide clarification. The formation of a continuous low impedance path (a homogeneous low melting point alloy), has been confirmed - which is the expected mode of operation.

Description: Proper handling of Ni-H2 cells/batteries in storage, during I&T, and at launch site is very important to preserve the useful energy and to extend the mission life. Cell reversal test is not a prudent test to verify or quantify the nickel pre-charge in Ni-H2 cells/batteries. The second plateau is due to the formation of Ni(+3) that is electrochemically inactive. Gas analysis of the cell, and chemical analysis of the positive plate are confirmatory tests to determine the nature of pre-charge in Ni-H2 cells.

Description: AEA performed a hard short study on various cell configurations whilst monitoring voltage, current and temperature. Video recording was also done to verify the evidence for cell venting. The presentation summarizes the results of the study including video footage of typical samples. Need for the diode protection in manned applications is identified. The standard AEA approach of using fused connectors during AIT for unmanned applications is also described.

Description: This viewgraph presentation gives an update on test results from two 16 cell batteries, one in a simulated Low Earth Orbit (LEO) environment and the other in simulated Geosynchronous Earth Orbit (GEO) environment. The tests measured how voltage and capacity are affected over time by thermal cycling.

Description: This viewgraph presentation describes the investigation of individual cell voltage dispersion under LEO and GEO cycling profiles. The contents cover: 1) Background; 2) Test Outline; 3) Single String Test Battery; 4) Goddard Space Flight Center (GSFC) 5Ah Battery; 5) Impedance; 6) Conclusions.

Description: A study consisting of electrochemical characterization and Low-Earth-Orbit (LEO) cycling of Li-Ion cells from three vendors was initiated in 1999 to determine the cycling performance and to infuse the new technology in the future NASA missions. The 8-cell batteries included in this evaluation are prismatic cells manufactured by Mine Safety Appliances Company (MSA), cylindrical cells manufactured by SAFT and prismatic cells manufactured by Yardney Technical Products, Inc. (YTP). The three batteries were cycle tested in the LEO regime at 40% depth of discharge, and under a charge control technique that consists of battery voltage clamp with a current taper. The initial testing was conducted at 20 C; however, the batteries were cycled also intermittently at low temperatures. YTP 20 Ah cells consisted of mixed-oxide (Co and Ni) positive, graphitic carbon negative, LIPF6 salt mixed with organic carbonate solvents. The battery voltage clamp was 32 V. The low temperature cycling tests started after 4575 cycles at 20 C. The cells were not capable of cycling. at low temperature since the charge acceptance at battery level was poor. There was a cell in the battery that showed too high an end-of-charge (EOC) voltage thereby limiting the ability to charge the rest of the cells in the battery. The battery has completed 6714 cycles. SAFT 12 Ah cells consisted of mixed-oxide (Co and NO positive, graphitic carbon negative, LiPF6 salt mixed with organic carbonate solvents. The battery voltage clamp was for 30.8 V. The low temperature cycling tests started after 4594 cycles at 20 C. A cell that showed low end of discharge (EOD) and EOC voltages and three other cells that showed higher EOC voltages limited the charge acceptance at the selected voltage limit during charge. The cells were capable of cycling at 10 C and 0 C but the charge voltage limit had to be increased to 34.3 V (4.3 V per cell). The low temperature cycling may have induced poor chargeability since the voltage had to be increased to achieve the required charge input. The battery has completed 6226 cycles. MSA 10 Ah cells consisted of Co oxide positive, graphitic carbon negative, LiPF6 salt mixed with organic carbonate solvents. The battery voltage clamp was 30.8 V. The low temperature cycling tests were started after 2182 cycles at 20 C. The cells were capable of cycling at 10 C and 0 C. Like SAFT, the voltage limit on charge had to be increased to 36 V (4.5 V per cell). There was a cell (cell S/N 13) in the battery that showed poor performance features such as low EOD voltage and high EOC voltage. The battery has completed 3441 cycles. A reconditioning procedure that consisted of C15 charge to a taper current of C/100 and C/20 discharge improved the voltage behavior of SAFT and MSA cells with no significant effect on YTP cells. We have demonstrated that the charge operation with VT clamp at battery rather than at cell level is feasible for onboard Li-Ion battery operation.

Description: 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.