010917 UN2 Battery Design Summary by ashrafp

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									                                           BATTERY SUMMARY
                                    University Nanosat Program, Nanosat-2

1.    INTRODUCTION

1.1     Purpose/Scope
The purpose of this document is to provide a summary of design details and test approaches for batteries
used on the Nanosat-2 program. It is also intended to provide supplemental information in support of
hazard report controls and control verifications. The information contained in this document is current as
of the date listed at the bottom of this page. This information may be superseded by future revisions of
the Flight Safety Data Package.

1.2     Background
1.2.1    Battery Summary
A complete listing of batteries and their relative locations on Nanosat-2 are shown in Table 1-1 and
Figure 1-1
                       Table 1-1: Summary of Batteries/Battery Types on Nanosat-2
                                                No. of Cells per
      Used On                Cell Type                                    Characteristics              Ref Page
                                                    Battery
                      NiCd rechargeable                            Open Bus Voltage: 28-33V
MSDS                                                  22                                                  10
                      Sanyo N4000DRL                               Pack Capacity: 4 A-h
                      NiMH rechargeable                            Open Bus Voltage: 14-18 V
ION-F/USUSat                                          11                                                  29
                      Sanyo HR-4/3FAUX                             Pack Capacity: 4.5 A-h
                      NiCd rechargeable                            Open Bus Voltage: 23 V
ION-F/Dawgstar                                        20                                                  11
                      Sanyo KR-1400AE                              Pack Capacity: 22 A-h
                      NiCd rechargeable                            Open Bus Voltage: 16-25V
ION-F/HokieSat                                        15                                                  11
                      Sanyo KR-1400AE                              Pack Capacity: 21 A-h
                      NiCd rechargeable                            Open Bus Voltage: 12 V
3CS (See Note 1)                                      10                                                  11
                      Sanyo KR2300SCE                              Pack Capacity: 2.3 A-h
Notes for Table 1-1
1. Three batteries are used on the 3CS stack, one for each satellite. Each battery is identical.
   Characteristics shown in the table are for a typical battery. Thus, the entire 3CS stack contains 30
   NiCd cells.
                    ION-F / USUSat
                    Sanyo NiMH HR-4/3FAUX                                   3CS Batteries
                    11 cells, series                                        3 Batteries (identical)
                    14-18 V, 4.5 A-h                                        Sanyo NiCd KR2300SCE
                                                                            @10 cells, series
                ION-F / Dawgstar                                            12 V, 4A-h
                Sanyo NiCd KR-1100AE
                20 cells, series
                23 V, 22 A-h
                   ION-F / Hokiesat                                       MSDS Battery
                   Sanyo NiCd KR-1400AE                                   Sanyo NiCd N4000DRL
                   15 cells, series                                       22 cells, series
                   16-25 V, 21 A-h  z                                     28 V, 4A-h
                              x
                            (AFT)


                                                                         SHELS Interface Plane

                                    Figure 1-1: Battery Locations, Nanosat-2


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1.2.2          Operational Scenario
Nanosat-2 is designed to operate at a minimum orbit of inclination 36 and altitude 350 km. Deployment
and operation of Nanosat-2 hardware occurs in five phases as shown in Figure 1-2. At T0, ejection of
Nanosat-2 from SHELS will trigger the start of timers on the MSDS via microswitches at the Nanosat-
2/SHELS separation plane.
At T1 (20 minutes), the MSDS will issue a signal to the nanosats via electrical connectors in the SSS.
This T1 signal will be used to remove safety inhibits for all systems except those identified as recontact
hazards. The T1 signal allows Nanosats to begin certain operations that do not pose a recontact hazard to
the Shuttle.       Such operations include battery charging, RF communication, verification of
position/attitude, etc.
Safety inhibits for recontact hazards are removed at T2, which occurs 4 days after ejection of Nanosat-2
from SHELS. Recontact hazards include such systems as stack and intersatellite separation systems,
propulsion systems, and deployable hardware. The four-day delay between T1 and T2 is intended to
provide the Shuttle with ample time to return to Earth.
At T3, an activation signal (time TBD) is simultaneously sent to both SSS’s, thus resulting in separation
of both stacks from the MSDS. At time T4, the intersatellite separation system will be activated by the
Three Corner Sat and ION-F stacks.
        T0 = 0:00                     T1   = T Safe, All Systems Except     T2     = TSafe,                T3   = T SEP               T4       = TSEP, Nanosat
                                                  Recontact Hazards                    Recontact Hazards
                                                                                                            = T0 + 96 hours, 4 secs   = T0 + 102 hours, 4 secs
                                           = 20 minutes                           = T0 + 96 hours

              MSDS released from       MSDS is 20 minutes out             Recontact hazard inhibits        Stack separation signal
                                                                                                                                       Intersatellite separation
                Orbiter/SHELS            from Orbiter,timers               removed aboard MSDS              releases both stacks
                                              time-out

                                                                          Recontact hazard inhibits
              MSDS timers initiated                                          removed aboard
                                       Safety inhibits removed                   Nanosats
                                        for all MSDS systems
                                          without recontact
                                                hazards.



                                       Safety inhibits removed
                                        for Nanosat systems
                                          without recontact
                                               hazards.




                                                                 INHIBITS STATUS MSDS AND NANOSAT
 Recontact
                    In-place                 In-place                             Removed                         Removed                      Removed
  Hazards
  All other                                                                                                                                    Removed
                   In-place                 Removed                               Removed                         Removed
  systems



                                            Figure 1-2: Nanosat Deployment Sequence




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2.    DESIGN SUMMARY

2.1   MSDS Battery
The MSDS battery is a 33 volt NiCd rechargeable battery with a capacity of 4 amp-hours. The battery
consists of 22 Sanyo N4000 DRL cells enclosed in a battery box. The battery box, shown in Figure 2-1 is
constructed of Al 6061-T6, with a stainless steel internal rib. The internal rib, which is bolted to the sides
of the box, provides a mounting structure for the batteries within the box. Hysol EA 9394 will be used to
bond the batteries to the internal rib. Six NAS-10 bolts will be used to attach the cover to the box and
attach the box to the MSDS. A viton gasket will be installed between the cover and box. To absorb
electrolyte in the event of a leak, sheets of Pigmat MAT301 will be installed in the battery box, above and
below the cells.
Several coatings will be applied to the battery box. Two of the coatings will be applied to the interior of
the box to prevent electrical conductivity and corrosion by the KOH electrolyte. Electro-less nickel per
AM-2404C will be first layer of interior coating. Uralane will be applied on top of the electro-less nickel,
as the second interior coating. The exterior of the box will have a MIL-C-5541E iridite coating. In
addition, the exterior of the box will be covered with black Teflon tape to provide a consistent emissivity.
The battery box will have two vents to prevent buildup of gases within box. Each vent hole will have a
stainless steel 400 x 400 mesh filter to prevent escape of electrolyte in the event that a cell leaks.
Figure 2-2 shows the internal wiring diagram for the battery box. An MS27472-T-19-F-32SA connector
provides pins for power and return, and measurement of the battery half-voltage. Four resistance
temperature detectors (RTD) are installed inside the battery box to monitor interior temperature. The
RTDs will be used to monitor temperature of the cells during charging on the ground but will not be used
after launch.

                                                                         LID




                                                                               LID GASKET




                                                                      CELL HOLDER




                                                                BOX




                           VENT HOLE MESH              CONNECTOR
                          VENT HOLE GASKET               GASKET

                        VENT HOLE COVER PLATE


                                        Figure 2-1. MSDS Battery




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                       5                                                             5

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                                                                  T
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                                                                  T
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                             Item #      Part #                           Quantity
                             1           MIL-W-22759/32-20                As
                                                                          Required
                             2           MIL-W-22759/32-24                As
                                                                          Required
                             3           MIL-R-23684/19                   4
                             4           MS27472-T-19-F-                  1
                                         32SA
                             5           Sanyo N4000 DRL                  22

                           Figure 2-2. Battery Box Interior Wiring Diagram

2.2   ION-F Battery
As indicated in Section 1.1, ION-F consists of three satellites. Two satellites Dawgstar and Hokiesat will
use a NiCd battery, while USUSat will use a Nickel- Metal-Hydride battery (see Table 1-1). All cells are
fabricated such that they are electrolyte-starved and are members of a family of batteries that have flight
history. The NiMH cell family has flown on the Extravehicular Helmet Interchangeable Portable (EHIP)
and the Rechargeable EVA Battery Assembly (REBA), and the same cell is planned for EHIP Light
(these are all standard EVA support tools flown regularly on the Space Shuttle). The NiCd family has
flight heritage on MightySat I. The batteries will not be operational while the satellite is in the orbiter and
will be inhibited with four independent inhibits.
The ION-F battery box design is being changed from the Phase 0/1 design. This change will eliminate
PVC from the battery box as required by NASA. The three ION-F battery boxes will differ in
construction due to different cell sizes and numbers, but each box will incorporate the same basic safety


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features. Each aluminum battery box consists of a main body and two gasketed covers. The interior of
the battery box will be anodized, thus making it non-conductive. In addition, the interior surfaces of the
box will have an anti-corrosive coating to prevent damage from electrolyte that contacts the structure.
Each box will contain two filtered vents (Gore Tex). Battery cells will be retained by a cell holder, which
is similar in design to the MSDS cell holder shown in Figure 2-1. In addition, PIG Mat 203 pillows will
be used to absorb excess electrolyte.
The placement of the vents will vary slightly among the battery box designs. In no satellite orientation
(during ground handling or while installed in the Shuttle) will there be a vent placed such that leaked
electrolyte could drain out the box via gravity.
Two US Sensor model 2121 Thermistors will be installed inside the battery box for temperature
monitoring when the batteries are being charged. Also contained in the battery box are two Raychem
SRP350 over-current protection devices.

2.3   3CS Battery
The cells used in all the 3CS battery packs will be of KR2300SCE Sanyo Cadnica series. The Sanyo
Cadnica is a sealed NiCd cell with a safety relief valve. The structure of the cell includes rolled plates
with a viscous electrolyte. Pressure buildup is possible under overcharging conditions. In case of extreme
overcharging, a spring loaded pressure gasket will release and decrease the cell’s internal pressure. Once
the pressure decreased, the gasket will seal up again. The cell structure is shown in Figure 2-3.
The battery pack will be a two-row configuration of the 10 cells which yields a 12V(nominal), 2.3Ah
battery pack Figure 2-4. The batteries are aligned in two rows of five, which are offset to allow fuse
placement at each end of the battery box. Thermal fuses (7A) will be installed on both the positive and
the negative end of the battery pack to protect against short circuits inside the battery and out. The pack
will be wrapped with Teflon insulators, and absorbent material, Pigmat 203. The wiring harness to the
battery will use 22AWG wire. Cell interconnects will be made using solder joints or spot welding by the
vendor (TBD). The battery pack will be enabled at T1, at which point it will accept charge from the
solar-array and provide power to the sub-systems.




                           Figure 2-3. Sanyo Cadnica Pressure Relief Valve



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Each 3CS spacecraft will house one vented battery box designed to contain any liquid discharge. The
boxes will be constructed of 6061-T6 Aluminum, a material that is highly resistant to stress corrosion
cracking (SCC). The batteries will be firmly secured to prevent vibration that might damage the cells.
The box will be sealed with four screws of size 4-40, that allow for quick and easy removal of the cover.
All internal aluminum surfaces will have non-conductive and non-corrosive coatings.
Two vent holes will be provided on the top of each box. Each vent hole is ¼-inch in diameter. The vent
holes are placed in the center of the box equidistant from the edges. The vents are located on the top of
the box, see Figure 2-5, so that they are not blocked by the isogrid or other parts of the spacecraft. A
stainless steel mesh cover each vent and will be used to prevent leakage of electrolyte. The mesh will
have 500 strands per linear inch and will have a 25 percent open area.
                                     Battery cells




                                                                    PIG MAT 203

                                                                       Non-conductive
                                                                       Teflon




             Helicoil insert/
             Screw holes
             4-40 x 4

                                                                   Aluminum Box
                                                                   (6061-T6)
                                                                   (6061T6
                                              Fuse space


                                 Figure 2-4. Battery box components




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                                                           1/4” Vented Hole X 2




                          Fine mesh over hole x 2
                          500 meshes per linear inch

                                   Figure 2-5. Battery Box Vent Holes

Because these containers are vented, a free volume analysis will be performed to determine if the amount
of gas evolved under worst case conditions will reach hazardous levels.




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3.   BATTERY CELL VERIFICATION TESTING
Battery cell and battery test requirements vary according to anticipated usage and resulting requirements
for safety (see Table 3-1). In the case of the MSDS battery, discharging will occur immediately upon
ejection from the payload bay (T0). Because of the proximity to the Shuttle, all MSDS battery cells are
subjected to acceptance and lot test program to minimize the possibility of internal/external shorting and
cell reversal. This testing also ensures that the MSDS battery will be able to perform its intended
function. In the case of university batteries, cells are neither charged nor discharged until 20 minutes
after Nanosat-2 is ejected from the payload bay (T1). Therefore, cell acceptance testing for university
batteries is not considered necessary from a safety perspective although some level of testing will be
conducted to maximize the possibility for mission success. Functional testing of the university battery
assemblies will be conducted at various points in the test program to verify that there are no internal or
external shorts.
Note: Although none of the batteries will be operated in the payload bay during flight, batteries may be
charged while in the orbiter on the launch pad. Nominally, the last battery charge would take place at the
OPF for both the university and MSDS batteries. A top charge is also possible if the shuttle is at the
launch pad in excess of 45 days.

              Table 3-1: Summary of MSDS and University Battery Testing, Nanosat-2

     Component              Mission Success-Oriented                          Safety Required
 MSDS Battery        See column right                          Acceptance Test: Mass, Dimensions, Visual
                                                               per MSDS Battery RFQ, dated 5/22/01
                                                               Acceptance Test: Leak Check per MSDS
                                                               Battery RFQ, dated 5/22/01
                                                               Acceptance Test: Capacity, Charge Retention,
                                                               and Internal Resistance Verification per MSDS
                                                               Battery RFQ, dated 5/22/01
                                                               Battery functional tests following system level
                                                               random vibration and thermal vacuum tests to
                                                               show that battery short circuit does not occur.
 ION-F Batteries     Acceptance Test: Visual/Leak Check,       Battery functional tests following satellite,
                     Open Circuit Voltage, Cell Matching per   stack, or system level random vibration and
                     UN-PLN-12328, Battery Cell Acceptance     thermal vacuum tests to show that battery
                     Test Plan, University Batteries           short circuit does not occur.
 3CS Batteries       Acceptance Test: Visual/Leak Check,       Battery functional tests following satellite,
                     Open Circuit Voltage, Cell Matching per   stack, or system level random vibration and
                     UN-PLN-12328, Battery Cell Acceptance     thermal vacuum tests to show that battery
                     Test Plan, University Batteries           short circuit does not occur.




                                                     8                                      Revision 9/17/01
Appendix A. Cell Specifications




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Information: Nickel Cadmium Cells (MSDS, 3CS, ION-F/Hokiesat & ION-F/Dawgstar)




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           Information: Nickel Metal Hydride Cells (ION-F/USUSat)




HR-4/3 AUX used on ION-F/USUSat




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