The present space qualified nylon separator, Pellon 2505 ML, is no longer available for aerospace nickel-cadmium (NiCd) cells. As a result of this anticipated unavailability, a joint Government program between the Air Force Space Division and the Naval Research Laboratory was established. Four cell types were procured with both the old qualified and the new unqualified separators. Acceptance, characterization, and life cycling tests are to be performed at the Naval Weapons Support Center, Crane, Ind. (NWSC/Crane). The scheduling and current status of this program are discussed and the progress of testing and available results are projected

Francis, R. W.

Haag, R. L.

English

NASA Technical Reports Server

N87-11085
AEROSPACE NICKEL-CADMIUM CELL SEPARATOR QUALIFICATIONS PROGRAM
R. W. Francis
The Aerospace Corporation
E1Segundo, California
R. L. Haag
Naval Weapons Support Center
Crane, Indiana
ABSTRACT
The present space qualified nylon separator, Pellon 2505 ML, is no
longer available for Aerospace nickel-cadmium (NiCd) cells. As a result of
this anticipated unavailability, a joint Government program between the Air
Force Space Division and the Naval Research Laboratory has been
established. Four cell types have been procured with both the old qualified
and the new unqualified separators. Acceptance, characterization, and life
cycling tests are to be performed at the Naval Weapons Support Center,
Crane, IN (NWSC/Crane). The scheduling and current status of this program
are discussed and the progress of testing and available results are
projected.
BACKGROUND
The qualified separator material for Aerospace hermetica]ly sealed NiCd
cells has been Pelion 2505 ML, produced by the Pelion Corporation. Pellon
2505 ML is a non-woven nylon fabric used for 15 years in the Aerospace
industry. In 1976 Pelion Corporation discontinued manufacture of the
2505 ML separator material. The fabrication process incorporated zinc
chloride in the bonding of fibers into structures and the process effluent
removal required costly treatment. In 1981 General Electric Battery
Business Division (GEBBD) informed al] users of this separator that
continued supply would be unavailable. GEBBD had stored enough of the 2505
ML separator to satisfy cell lot commitments to the end of 1984. Concern
over this issue encouraged Pelion to reactivate their 2505 ML production
line. In the interim, however, enough changes in the raw nylon fibers and
processing equipment were made that product characteristics were variable.
During this period, GEBBD was coordinating their separator physical,
mechanical and chemical parameter needs with Pelion Corporation. A new
nonpolluting process, similar to that used in their German manufacturing
plant for I0 years, was introduced and installed into the U.S. Pelion plant
to manufacture separator material. GEBBD and Pelion claimed that the new
separator, 2536, was superior from a uniformity, durability, and performance
standpoint. Comparative characteristics and evaluations between the 2505 ML
and 2536 separator types appeared encouraging. This preliminary data along
169
https://ntrs.nasa.gov/search.jsp?R=19870001652 2020-03-23T14:59:29+00:00Z
with the new separator qualification program definition and structure were
published by M. Milden at the Intersociety Energy Conversion Engineering
Conference in 1984 (Ref. I). The essential elements of this program have
been updated and are listed below:
O Air Force Space Division and Naval Research Laboratory procurement
of typical military cells from GEBBD.
O Coordinate with spacecraft battery contractors to insure test plan
validity and performance acceptability.
o NWSC/Crane to perform acceptance, characterization and life cycle
testing.
o Generate a consolidated data base for the military customer and the
battery contractors/users.
o Eliminate duplication of effort and qualification costs.
More recent analysis (Ref. 2) of the Pellon 2536 separator, which was
performed at the Aerospace Corp. Laboratories, shows characteristics
apparently equivalent, if not superior, to that of the standard Pelion 2505
ML. Table I illustrates and compares these pertinent component parameters.
PROGRAM STRUCTURE
The Air Force and Navy have similar NiCd cell requirements and needs.
Program efficiency to provide overall benefit was attained through joint
military funding for a single and con,non cell buy. A coordinated program
management function is established at NWSC/Crane. Technical support,
component testing, military and program office interface, and data analysis
are being conducted by The Aerospace Corporation. The Air Force Space
Division Product Assurance Division AFSD/PDP coordinates, monitors and
transfers funds to NWSC/Crane; whereas, the Naval Research Laboratory
provides the same function for the Navy. Prior to 1985 the Air Force and
Navy had already allocated the necessary money to purchase a total of 173
cells. The division of cells for test and evaluation are shown in Table 2.
Negative electrodes are all silver treated except the 26.5 A-Hr cells which
have teflon treatment. Positive electrodes consist of the current and
standard process design. Half of each cell type is constructed with Pelion
2505 ML and half with the proposed new Pelion separator 2536.
Cell specification is not program specific but performance oriented.
The specification establishes requirements for manufacturing methods and
procedures and defines processes and fabrication methods at a point in time
for a NiCd cell type.
170
CELL TESTING AND EVALUATION
After cells are received at NWSC/Crane, they undergo three separate but
consecutive tests. These are:
o Acceptance
o Characterization
o Life Cycling
i) Acceptance testing at Crane enables performance comparison to acceptance
test data from GEBBD and provides a basis for cell matching and pack
fabricaton.
2) Characterization testing is performed on all cell types after being
subjected to random vibration to simulate the launch environment.
Following vibration the cells will be placed in restraining plates with
temperature monitoring. Following a conditioning cycle and ten capacity
stabilization cycles the cells will undergo voltage characterization at
various charge current rates (C/2 to C/80) and temperatures (30 ° to
-10°C). These characterization tests will differentiate between the two
separator types according to the electrochemical mass transport
capabilities. In other words, the existing voltage-temperature charge
curves will be requalified for the Pellon 2536 separator in relation to
the existing Pellon 2505 ML.
As seen in Table 2, cell types will also be stored in both the activated
(wet storage) and unactivated (dry storage) state as elapsed test time
controls for comparative analysis.
3) The life cycling test matrix consists of 135 cells and is illustrated in
Table 3 with the test details shown in Table 4.
The cells are assembled into five- and ten-cell packs following a pack
fabrication procedure which is weighted with eleven parameters from the
NWSC/Crane acceptance tests. For both orbits, two test levels are
imposed to simulate both actual and accelerated performance behavior.
For the low earth orbit (LEO) only, the higher temperature and greater
depth of discharge is used to enhance any performance level limitations
for either separator. The geostationary orbit (GEO) is considered
accelerated, since no trickle charging, simulating conditions between
eclipse seasons, is imposed. The two GEO temperature levels will
bracket actual use environments. The LEO orbital simulation consists of
a 33.6-minute (0.56 Hr.) eclipse and a 67.2-minute (1.12 Hr.) sunlight
period. The cycling is continuous with no scheduled capacity
measurements or reconditioning. The preselected temperature-compensated
voltage limit (V/T-limit) is chosen to maintain a charge-to-discharge
ratio of 1.00-1.08, including the taper current. The GEO orbital
simulation consists of a typical 42-day eclipse season, and following
each season the packs are trickle charged at C/60 for two days. Each
pack is to be reconditioned to 0.75-volt average pack voltage for
approximately ten days following the trickle charge. Recharge prior to
171
the next season is at the C14 rate. Within an eclipse season, cell packs
are charged at the C/IO rate to a V/T-limit followed by a taper current
charge for the remainder of the eclipse day.
STATUS AND SCHEDULE
The joint Air Force/Navy separator qualification program has been funded
up to and including FY 90. A chronological list of key program milestones
are listed below:
o Procurement Specification Sep 1983
o Contract with GEBBD for Procurement
of 154 NiCd Cells
Mar 1984
o Amend Contract to Add 19 Additional
50 A-Hr Cells
Aug 1984
o Contract Modifications and
Material Review
Jun 1985
o 30 and 34 A-Hr Cells Consigned
to NWSC/Crane
Jun 1985
o Detailed Test Plan Sep 1985
o 35 and 50 A-Hr Cells Consigned
to NWSC/Crane
Nov 1985
The current status and projected test schedule at NWSC/Crane is illustrated
in Table 5 on a time-line diagram.
At the time of this writing, as can be seen in Table 5, the first of the
four cell types, 42B034AB02 and 03 (34 A-Hr cells), has completed acceptance
testing at Crane. The raw data demonstrates comparable and nominal
capacities for both the Pelion 2505 ML and 2536 separator types in the 25 °,
i0 °, and 0°C capacity and overcharge acceptance tests. In addition, the
typical roll-over in charge voltage was observed for both cell types,
indicating good negative plate electrochemical behavior. Maximum charge
voltage for the Pelion 2536 cells, however, is attained earlier in the
alloted time for charge than for the Pelion 2505 ML. The significance of
this will not be known until the characterization tests are completed and
the llfe cycling initiated.
FUNDING
Not including cell procurement costs, which have been appropriated, the
funding level allocated by the Air Force and Navy for the qualification test
program alone is approximately _I50K per year up to FY 91. These funds
represent the required support to conduct the acceptance, characterization,
and life cycle tests. Thus, life cycle testing is ensured for almost five
172
years, since all cell types are projected to have completed their acceptance
tests at NWSC/Crane by February 1986.
The structure of the separator test program was designed to provide a
high degree of confidence based on long term testing exposing any subtle
differences far in advance of actual flight usage. As a result of an
accelerated schedule in the military which forces utilization of the new
Pellon 2536 separator for near-term cell lot buys, the separator
qualification test program has received the support and encouragement of
many spacecraft program offices. Preliminary test evaluation data to
demonstrate _omparable performance and acceptability of the new material to
that of the Pellon 2505 ML will not be available, however, with any degree
of confidence and reliability until the end of 1986. This will obviously
impact decisions to purchase NiCd cells with the new Pellon 2536 separator
for spacecraft flight use.
CONCLUSION
The NiCd cell separator qualification program will provide a common data
base for the comparison of performance characteristics of cells with Pellon
2505 ML and identical cells with Pellon 2535 in concurrent tests.
Preliminary life cycle data at more severe temperatures and discharge depths
will be available by the end of 1986 to verify cell performance with the new
Pellon 2536. Close to five years of long-term real-time cell cycling is
funded to verify cell performance and acceptability of the Pellon 2536
separator. Joint Air Force and Navy funding to one centralized facility,
_SC/Crane, will produce a statistically more valid data base at an overall
lower cost by minimizing individual spacecraft program office evaluation,
management, coordination, and testing. This will enhance the value of the
data base by enabling direct comparison of the two cell types with different
separator components.
Test reports will be issued after each cell type acceptance test and
after each characterization test. In addition, NWSC/Crane will distribute
annual cycle life test reports and trends analysis at selected times
throughout the year. These reports will be made available on request to
NWSC/Crane and will be distributed in normal fashion subject to approval
from the Air Force and Navy.
REFERENCES
I. Milden, M. J. and Harkness, J., Proceedings of the Nineteenth
Intersociety Energy Conversion Engineering Conference !, 108 (1984).
2. Badcock, The Aerospace Corp., Private Communication, Oct. 31, 1985, to
be published.
173
TABLE i. SEPARATOR PARAMETRIC COMPARISON
Parameter 2505 ML 2536
Process
Fiber Diameter
Density
Electrolyte
Retention
Hydrolysis
Rate (70°-I00°C)
*31% KOH
*Cd +2 Added
Zn CI 2 Stabilized
Bonded Nylon
13 m
400%
High temperature
Inert Gas
Bonded Nylon
13 m
1.25 (2505 ML)
300%
0.5 (2505 ML)
0.5 (2505 ML)
TABLE 2 CELL TEST DISTRIBUTION
A-Hr
Capacity
26.5
34
35
50
Cell Type
Designation
42B030ABI0/14
42B034AB02/03
42BO35AB02/13
42BO50AB24/28
Test
Matrix
GE
Destruct
Quantity/End Use
Wet Dry
Storage Storage
30
30
30
45
135
i
1
1
I
4
2 2
2 2
2 2
5 3
11 9
Characterization
4
2
4
4
14
174
TABLE 3. TEST MATRIX
Orbit
DoD
Actual
Charge
Control
V-T
LEO 25 Taper 0
V-T
LEO 40 Taper 20
GEO V-T
Accel 75 Taper 0
GEO V-T
Accel 75 Taper 20
2505 ML Separator
50AH 34AH 35AH 26.5AH
5 5
I0 I0
5 5
i0 I0
2536 Separator
50AH 34AH
5 5
10 10
I0
35AH 26.5AH
I0
10
TABLE 4. LIFE CYCLE DETAILS
Tes I:
LEO, 25_, 0°C
LEO, 40%, 20°C
GEO, 75%, O°C
GEO, 75%, 20°C
Capacity
Nameplate Est.
26.5AH
34
5O
Actual
Current
Discharge Charge
26.5
34
5O
35AH
50
35
5O
30AH
41
5O
30
&l
5O
13.4A c/3
18.3 c/2
22.3 c/3
21._ c/2
29.3 c/2
35.7 c/2
37AH
5O
37
5O
23.1A c/10
31.3 cll0
23.1 c/10
31.3 c/10
V/T
Curve
C/D
Range
5 1.00-1.08
5 1.00-1.08
5 1.00-1.08
5 1.00-1.08
5 1.00-i.08
5 1.00-1.08
Taper Current
5 0.5 -0.3A
5 0.75-O. 5A
5 0.5 -0.3A
5 0.75-0.5A
175
Acceptance Tests
30 A-Hr
34 A-Hr
35 A-Hr
50 A-Hr
Characterization
30 A-Hr
34 A-Hr
35 A-Hr
50 A-Hr
Life Cycling Tests
30 A-Hr
34 A-Hr
35 A-Hr
50 A-Hr
Test Reports
TABLE 5. CURRENT AND PROJECTED SCHEDULE
1985
Sept. Oct. Nov.
1986
X_X
X_X
X
X-
Dec. Jan.
X--X
X--X
Feb.
X--X
X--X
I
Mar. Apr.
X--X
X--X
I I
X
X
May
xl
176


Aerospace nickel-cadmium cell separator qualifications program

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server