The feasibility of using nickel cadmium batteries as an alternate if flight qualified NiH2 batteries are not available is explored. Battery life expectancy data being a key element of power system design, an attempt is made to review the literature, life test data and in orbit performance data to develop an up to date estimate of life expectancy for NiCd batteries in a geosynchronous orbit

Broderick, R. J.

English

NASA Technical Reports Server

Ni-Cd BATTERY LIFE EXPECTANCY IN 
GEOSYNCHRONOUS ORBIT 
Richard J. Broderick 
GTE Satellite Corporation 
ABSTRACT 
Nickel Cadmium battery life expectancy data is required as one key 
element of a power system design. However, at present there are no widely 
accepted analytical models for predicting NiCd life expectancy for a geo- 
synchronous orbit. This paper is an attempt to review the literature, life 
test data, and in orbit performance data to develop an up to date estimate 
of life expectancy for NiCd batteries in a geosynchronous orbit. 
INTRODUCTION 
GTE Satellite Corporation (.GSAT) is a subsidiary of General Telephone 
and Electronics Corporation, one of the nation's leading communication and 
electronics enterprises. In December 1980, GSAT was granted authority by 
the Federal. Communications Connnission to construct and operate an advanced 
domestic communications satellite system providing customized digital 
transmission networks to a variety of users. GSAT's new satellite system 
is scheduled for operation in mid 1984. The space segment consists of two 
satellites operating in the 12/14 GHz frequency band, with two satellites 
to be held in reserve. The first satellite, GSTAR 1, is scheduled for 
launch in the second quarter of 1984. 
The GSTAR baseline design uses three 30 Ampere-hour Nickel Hydrogen 
batteries. However, a parallel alternative is being developed in which 
three 27 Ampere-hour Nickel Cadmium batteries will be used if flight qual- 
ified NiH batteries are not available. A study was initiated to examine 
the feasi b ility of this alternative. Initially a literature search was 
conducted with respect to the life expectancy of NiCd cells in a geosyn- 
chronous orbit. Life test data, prepared by the Naval Weapons Support 
Center (NWSC) at Crane, IN, manufacturing data and in orbit flight 
experience was reviewed and compiled. A curve was deduced, from the 
compilation of the various sources, for a prudent design criterium for 
batteries built in 1983 with respect to life versus depth of discharge 
(DOD). The data was not scrutinized to remove "bad apples" but was 
plotted as objectively as possible. The study assumes that deep discharge 
reconditioning (DDR) circuitry is available on the Spacecraft and that 
average battery temperatures over the year will be less than 15'~. No 
attempt was made to study only certain manufacturers or certain specific 
cell designs. The paper will be organized into a discussion of the 
literature search, life test data, in orbit performance data, life 
expectancy, and conclusions. 
https://ntrs.nasa.gov/search.jsp?R=19840025616 2020-03-22T10:19:13+00:00Z
LITERATURE SEARCH 
Figure 1 presents life expectancy for a NiCd battery operating at less 
than a 15'~ average temperature in geosynchronous orbit, The curve is 
actually presented as allowable depth of discharge versus expected life time 
in years. The first user, GSFC, adopted this convention so I w%ll continue 
using this format, whereas my personal application will be given a DOD as to 
what life time I can expect. This figure originally appeared in Reference 1, 
but recently appeared in Reference 2. The figure was originally plotted in 
terms of actual DOD. 1 have scaled it up to rated DOD assuming actual 
capacity to be 110% of rated. Since this curve appeared in 1976 I will use 
it as my 1976 baseline performance for MiCd life expectancy in a geosynchro- 
nous orbit. 60% DOD for this case would indicate a 3.4 year life. 
Figure 2 presents another estimate of where life expectancy was and also 
where it was capable of going (Ref, 3). Sparks emphasized the importance of 
temperature control and DDR in extending life performance, This absicissa 
and ordinate will be used repeatedly for baseline comparison. As an example 
we will take 60% DOD and follow it through the paper. Sparks indicates that 
in 1973 one could expect a 5 year life and a capability of 15 years life at 
60% DOD. 
LIFE TEST DATA 
Figure 3 presents real time life test data from the Crane Life Test 
program (Ref. 4). This figure only considers test packs with operating 
temperatures below 15'~. Three distinctions are made for the plotted data: 
failed cells, discontinued packs and ongoing tests. If we draw a curve 
between the earliest cell failures, we get a curve which correlates well 
with the earlier cell performance curves. A second curve drawn through the 
later cell failures would be indicative of what good cells can do. As you 
can see there are packs which have gone beyond this point before being dis- 
continued, or are still continuing to date. The packs that were discontinued 
had cell failure(s) earlier in the test but continued cycling the remaining 
cells. Table 1 summarizes this data and shows what packs are associated 
with the points plotted. I think the dotted line would be a compromise 
curve, if one could be drawn, for this data, 60% DOD would indicate a 7.2 
year life. 
Figure 4 also shows Crane real time life test data for 20-25O~. The 
dotted line represents a compromise curve for this scattering of data. This 
line is not much different than the less than 15'~ curve. However, it does 
go in the logical direction of increased temperature and decreased life ex- 
pectancy. Table 2 summarizes this data. 60% DOD would indicate a 7 year 
life. 
Figure 5 is a plot of accelerated life test data which was available, 
and this data is summarized in Table 3. The FLTSATCOM accelerated life test 
program claims 44 simulated eclipse seasons of life (Ref, 5). This data 
p o i n t  could be  i n d i c a t i v e  of g r e a t  t h i n g s  t o  came. However, a t  t h i s  time I 
don ' t  t h i n k  one can skew a curve o u t  t o  22 yea r s  a t  75% DOD, My es t ima te  
of a reasonable  r e p r e s e n t a t i o n  of t h e  d a t a  is shown. 60% DOD would i n d i c a t e  
an  8.4 y e a r  l i f e  f o r  t h i s  curve. 
I N  ORBIT PERFORMANCE 
Figure  6 indicates i n  o r b i t  performance t o  d a t e  f o r  a v a i l a b l e  SIC. Same 
of t h e  p o i n t s  shown are des ign  requirements as opposed t o  a c t u a l  f l i g h t  per- 
formance. The curve shown tends t o  show t h e  l ead ing  performances t o  da t e .  
Since most S/C o p e r a t e  over  a range of DOD, t h e  ranges  a r e  shown. 60% DOD 
would i n d i c a t e  a 7 year  l i f e  f o r  t h i s  curve. Table 4 summarizes t h i s  da t a .  
F igure  7 is a composite of t h e  curves p rev ious ly  shown. Real  t ime l i f e  
(RTL), a c c e l e r a t e d  l i f e  t e s t  (ACL), and i n  o r b i t  performance (IOP), tend t o  
be reasonably c lose .  A l l  t h r e e  i n d i c a t e  t h e  improvement from 1976. S ince  
10P and RTL do c o r r e l a t e  w e l l  w i th  ACL, I w i l l  use  ACL a s  being representa-  
t i v e  of 1983 s t a t e  of t h e  art .  This  would a.gain r ep re sen t  an 8.4 yea r  l i f e  
f o r  60% DOD. 
F igure  8 now shows j u s t  t h e  1976 and 1983 curves  f o r  l i f e  expectancy. 
For 60% DOD we see an  improvement from 5 yea r s  t o  8.4 yea r s ,  o r  3.4 yea r s .  
I f  we assume t h a t  improvement over t h e  next  7 yea r s  was t o  cont inue  a t  h a l f  
t h i s  r a t e ,  w e  may expect  a 1.7 year  improvement. The curve marked d e s i r e d  
i n d i c a t e s  cells b u i l t  today us ing  1983 NiCd technology could poss ib ly  last 
10.2 y e a r s  a t  60% DOD. 
CONCLUSION 
A s tudy  w a s  done t o  examine where NiCd technology was i n  terms of DOD 
ve r sus  l i f e  time f o r  b a t t e r i e s  i n  geosynchronous o r b i t .  The assumption was 
made t h a t  c e l l s  would be  opera ted  i n  a n  average temperature environment 
below 1 5 ' ~  and sub jec t ed  r o u t i n e l y  t o  deep d ischarge  recondi t ion ing .  Real 
time l i f e  t e s t  d a t a ,  a c c e l e r a t e d  l i f e  t e s t  d a t a ,  and i n  o r b i t  performance 
d a t a  were examined a s  t o  expected l i f e  as a func t ion  of depth of d i scharge .  
The r e s u l t s  would i n d i c a t e  t h a t  a prudent b a t t e r y  des ign  f o r  1983 f o r  a 
60% DOD would be  a n  8.4 yea r  l i f e  expectancy. A des i r ed  l i f e t i m e  f o r  t h i s  
DOD could r a t i o n a l l y  b e  10.2 yea r s .  
SYMBOLS 
ACL Accelerated life test 
C Continuing 
D Discontinued 
DDR Deep Discharge Reconditioning 
DOD Depth of Discharge 
F Failed Cell 
GSAT GTE Satellite 
IOP In Orbit Performance 
NWS C Naval Weapons Support Center 
RTL real time life test 
T a b l e  1 
C r a n e  L i f e  T e s t  -- R e a l  Time 
TEMP C')
COMPLETED 
ECLIPSE SEASONS PACK # DOD (%) STATUS 
T a b l e  2 
C r a n e  L i f e  T e s t  -- R e a l  Time 
COMPLETED 
DOD (%) TEMP (OC) ECLIPSE SEASONS PACK // 
2 2 1 A  
STATUS 
T a b l e  3 
A c c e l e r a t e d  L i f e  T e s t  D a t a  
G e o s y n c h r o n o u s  
COMPLETED 
DESCRIPTION DOD (%) TEMP (OC) ECLIPSE SEASONS 
NWSC 231A 80 10 9 
NWSC 2273 52 15 12 
NWSC 227F 5 2 15 
FACC INTELSAT V 55 10 
(Ref. 6) 
FACC INSAT 
(Ref. 6) 
RCA (1) 66 11 
RCA (2) 66 14 
TRW FLTSATCOM 75 9 
(Ref. 5) 
T a b l e  4 
I n  O r b i t  P e r f o r m a n c e  D a t a  
PERFORMANCE (YEAR) 
PROGRAM DOD(%) TEMP (OC) ACTUAL EXPECTED DESIRED 
TDRS S 5 0 5 10 
GOES 
IUE 57-60 15 
FLTSATCOM 1 65-70 <15 
2 65-70 <15 
3 65-68 <15 
4 65-68 <15 
SATCOM 1 55-58 










Ni-cd Battery Life Expectancy in Geosynchronous Orbit

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server