No significant degradation of nickel cadmium battery performance in SATCOM F1 and F2 after almost 8 and 7-3/4 years in orbit was shown. Battery minimum discharge voltage data are presented for these spacecraft. In addition, 2 groups of nickel cadmium cells which are representative of those in orbit are undergoing real time eclipse-reduced suntime cycling in the laboratory. These groups of cells, which are being cycled at a maximum of 53% and 62% depth of discharge (based on actual capacity), have completed 14 and 15 eclipse seasons, respectively. Data for these groups of cells are presented and are compared with the in-orbit battery data

Gaston, S. J.

Schiffer, S. F.

English

NASA Technical Reports Server

RCA SATCOM BATTERY IN-ORBIT PERFORMANCE UPDATE 
AND ACCELERATED LIFE TEST RESULTS 
Stephen J. Gaston 
Stephen F. S c h i f f e r  
RCA - Astro-Electronics  
Pr ince ton ,  N . J .  
ABSTRACT 
The o l d e s t  ope ra t ing  RCA Astro geos t a t iona ry  s p a c e c r a f t ,  SATCOM F1 and 
F2, have now completed almost 8 and 7-314 yea r s  i n  o r b i t ,  r e s p e c t i v e l y ,  w i th  
no s i g n i f i c a n t  degrada t ion  of t h e i r  nickel-cadmium b a t t e r y  performance. 
Ba t t e ry  minimum discharge  v o l t a g e  d a t a  are presented  f o r  t h e s e  s p a c e c r a f t .  
I n  a d d i t i o n ,  2 groups of nickel-cadmium c e l l s  which a r e  r e p r e s e n t a t i v e  
of those  i n  o r b i t  a r e  undergoing r e a l  t ime eclipse-reduced suntime cyc l ing  
i n  t h e  l abo ra to ry .  These groups of cells, which are be ing  cyc led  a t  a maximum 
of 53% and 62% depth of d i scharge  (based on a c t u a l  c a p a c i t y ) ,  have completed 
14 and 15  e c l i p s e  seasons ,  r e s p e c t i v e l y .  Data f o r  t h e s e  groups of c e l l s  a r e  
presented and a r e  compared wi th  t h e  in -o rb i t  b a t t e r y  da t a .  
INTRODUCTION 
Eight (8)  geos t a t iona ry  s p a c e c r a f t ,  manufactured by RCA Ast ro ,  a r e  
p re sen t ly  ope ra t ing  i n  o r b i t .  A s  descr ibed  previous ly ,  i n  References (1) 
and (2 ) ,  t h e  nickel-cadmium b a t t e r i e s  i n  a l l  of t h e s e  spacec ra f t  con ta in  
unique b a t t e r y  r econd i t i on ing  c i r c u i t r y  which permi ts  i nd iv idua l  c e l l  recon- 
d i t i o n i n g  t o  p r a c t i c a l l y  zero  v o l t s  without  t h e  danger of c e l l  r e v e r s a l .  
The o l d e s t  and longes t  ope ra t ing  of t h e s e  s p a c e c r a f t ,  SATCOM F1 and F2, 
have now completed almost 8 and 7-3/4 y e a r s ,  r e s p e c t i v e l y ,  i n  o r b i t  without  
any n o t i c e a b l e  degrada t ion  i n  b a t t e r y  performance. Ba t t e ry  d a t a  f o r  both of 
t h e s e  spacec ra f t  a r e  summarized he re in .  
In  a d d i t i o n ,  d a t a  from t h e  r e a l  t ime ecl ipse-reduced suntime l i f e  
cyc l ing  of groups of r e p r e s e n t a t i v e  c e l l s  i n  t h e  l abo ra to ry  a t  two depths of 
d i scharge  have been overlayed over t h e  in -o rb i t  da t a .  The r e s u l t s  show a 
remarkable s i m i l a r i t y  i n  "Minimum Discharge Voltage v s .  Ec l ipse  Season1' re- 
s u l t s  between t h e  l abo ra to ry  l i f e - c y c l i n g  c e l l s  and a c t u a l  i n -o rb i t  b a t t e r y  
performance over t h e  15  e c l i p s e  seasons p re sen t ly  achieved.  
BATTERY PERFORMANCE I N  ORBIT 
RCA Ast ro  has  manufactured 8 geos t a t iona ry  s p a c e c r a f t  which a r e  present -  
l y  ope ra t ing  i n  o r b i t  us ing  nickel-cadmium b a t t e r i e s .  Their  nomenclature 
and launch d a t e s  a r e  l i s t e d  i n  Table 1. A l l  b a t t e r i e s  a r e  performing w e l l .  
https://ntrs.nasa.gov/search.jsp?R=19840025620 2020-03-22T10:18:52+00:00Z
The b a t t e r y  performance of SATCOM F1 and F2 i s  of prime i n t e r e s t  s i n c e  they 
have been ope ra t ing  t h e  longes t  i n  o r b i t ,  almost 8  and 7-314 y e a r s ,  re-  
s p e c t i v e l y .  Their  des ign  and e a r l i e r  mission performance were r epo r t ed  i n  
1980 (Reference 1 )  and a t  t h e  1976 through 1982 Goddard Space F l i g h t  Center 
Ba t t e ry  Workshops. 
Figure 1 shows t h e  maximum average depth-of-discharge (DOD) f o r  t h e  
SATCOM F1 and F2 b a t t e r i e s  a s  a func t ion  of e c l i p s e  season. For both  F1 and 
F2 it ranges from 57% t o  52% based on t h e  nominal capac i ty  f o r  t h e i r  f i r s t  
14 and 12  e c l i p s e  seasons,  r e s p e c t i v e l y .  For F2 on e c l i p s e  season 1 3  t h e  DOD 
was reduced t o  42% s i n c e  t r a f f i c  was t r a n s f e r r e d  t o  t h e  SATCOM 3 and 4 s a t e l -  
l i tes .  The loads  on both spacec ra f t  were f u r t h e r  reduced t h i s  yea r  when 
SATCOMS 6 and 7 were lannched. 
F igure  2 shows t h e  minimum average b a t t e r y  vo l t age  f o r  SATCOM F1 and F2 
a s  a  func t ion  of t h e  number of e c l i p s e  seasons i n  o r b i t .  SATCOM F2 had re -  
ceived a  forced  d a i l y  e c l i p s e  of approximately 27% depth-of-discharge during 
t h e  cont inuous suntime du ra t ion  u n t i l  e c l i p s e  season number 6 .  This  d a i l y  
e c l i p s e ,  i n  conjunct ion wi th  a  l e s s  t han  f u l l  recharge achieved between these  
e c l i p s e s ,  had r e s u l t e d  i n  some vo l t age  degrada t ion .  This vo l t age  however, 
recovered when t h e  d a i l y  e c l i p s e  sequence was d iscont inued  fol lowing e c l i p s e  
season number 6 .  The b a t t e r i e s  of bo th  spacec ra f t  i n  genera l  show very smal l ,  
i f  any, vo l t age  degrada t ions ,  excluding e c l i p s e  season number 1 on F1 and 
c o r r e c t i n g  f o r  t h e  d i f f e r e n t  regime app l i ed  t o  F2 during t h e  f i r s t  6  seasons 
a s  descr ibed  above. 
Figure 3 shows t h e  same d a t a  a s  f o r  Figure 1, except  i t  p re sen t s  t h e  
minimum average c e l l  vo l t age  us ing  an  expanded s c a l e  and shows t h e  p red ic t ed  
vo l t age  degrada t ion  e s t a b l i s h e d  e a r l i e r  us ing  Crane d a t a  of packs 207A and 
209A (Reference 3 ) .  It can be noted t h a t  t h e  vo l t age  degradat ion was con- 
s ide rab ly  l e s s  than  was p red ic t ed  and c e l l  vo l t age  i s  s u b s t a n t i a l l y  above t h e  
minimum requi red  f o r  a  f u l l  payload ope ra t ion .  
CELL PERFORMANCE I N  ACCELERATED LIFE CYCLE TESTING 
In  e a r l y  1981, RCA began a  r e a l  t ime ecl ipse-reduced suntime l i f e  t e s t  
of two groups of 17Ah (nameplate) nickel-cadmium c e l l s  a s  used on t h e  ANIK B 
and SATCOM 3 and 4 s p a c e c r a f t .  The c e l l s  were manufactured by G.E. i n  1979 
and a r e  of t h e  same gene r i c  design a s  used i n  t h e  o t h e r  RCA spacec ra f t  
b a t t e r i e s  (Ref. GE P I N  42B017AB01). 
The c e l l s  a r e  be ing  cycled i n  a  t y p i c a l  44-day geosynchronous ec l ip se -  
cyc l ing  regime. Maximum depth of d i scharge  i s  based on an i n i t i a l  average 
capac i ty  of 19.8 Ah a t  5°C. Group A ( con t ro l )  i s  be ing  discharged a t  8 .9 
amperes; i t s  maximum DOD i s  8.9 A x 1.183 hour s l l9 .8  AH = 53.2% based on 
a c t u a l  and 62% based on nameplate capac i ty .  Group B (higher  DOD) i s  be ing  
discharged a t  10.4 amperes; i t s  maximum DOD i s  62% based on a c t u a l  and 72% 
based on nameplate capac i ty .  These d a t a  have been added t o  F igure  1 a s  shown 
i n  Figure 4.  In  t h i s  t e s t ,  t h e  "suntime" du ra t ion  has  been reduced from 138 
days t o  4 days f o r  recondi t ion ing .  
The depth  of d i scharge  f o r  t h e  test c e l l  groups, r e l a t i v e  t o  t h e  ba t -  
t e r i e s  i n  o r b i t ,  and minimum average b a t t e r y  vo l t ages  (7 c e l l  d a t a  s ca l ed  
t o  22 c e l l  b a t t e r y  vo l t ages )  have been added t o  F igures  1 and 2 as shown i n  
Figures  4 and 5 .  Although t h e  abso lu t e  vo l t age  va lues  a r e  lower than  t h e  
in-orb i t  r e s u l t s ,  a s  would be expected due t o  t h e  h igher  depths of d i scharge  
appl ied ,  t h e  t r e n d s  over  15  e c l i p s e  seasons of s imulated o r b i t  t e s t i n g  a r e  
remarkably s i m i l a r  t o  t hose  i n  t h e  s p a c e c r a f t .  Tes t ing  of t h e s e  c e l l s  w i l l  
cont inue u n t i l  f a i l u r e ,  t o  provide an input  f o r  p r e d i c t i n g  t h e  l i f e  of n icke l -  
cadmium b a t t e r i e s  a t  t h e s e  h igher  depths  of d i scharge  i n  o r b i t .  
CONCLUSIONS 
1 )  On RCA Geostat ionary Ba t t e ry  In-Orbit Performance 
Both SATCOM F1 and F2 b a t t e r i e s  r epo r t ed  h e r e i n  have been ope ra t ing  
succes s fu l ly  i n  o r b i t  f o r  about 8  and 7-314 yea r s ,  r e spec t ive ly .  Thei r  end- 
of-discharge v o l t a g e  degrada t ion  wi th  i n c r e a s e  i n  e c l i p s e  seasons has been 
minimal f o r  approximately equal  depth-of -d is~harges .  This  degradat ion i s  con- 
s ide rab ly  lower than  o r i g i n a l l y  p red ic t ed .  This  can  be  a t t r i b u t e d  t o  a  l a r g e  
ex ten t  t o  t h e  unique RCA Ast ro  r econd i t i on ing  procedure app l i ed  p r i o r  t o  each 
e c l i p s e  season.  
2) On Real  Time Eclipse-Reduced Suntime L i f e  Cycling i n  t h e  Laboratory 
The extended depth-of d ischarge  group of c e l l s  (62% based on a c t u a l  ca- 
pac i ty )  and t h e  c o n t r o l  group (53% DOD based on a c t u a l  capac i ty )  have shown 
only minimal vo l t age  degrada t ion  over t h e  equiva len t  of 15 e c l i p s e  seasons.  
Comparing t h e s e  d a t a  t o  t h e  in -o rb i t  d a t a  shows good concurrence t o  d a t e .  
REFERENCES 
1. Gaston, S. J.: RCA SATCOM F1 and F2 Ni-Cd Bat te ry  O r b i t a l  Performance, 
Proceedings of t h e  15 th  I n t e r s o c i e t y  Energy Conversion Engineering 
Conference, 1980, Reference 809320. 
2. Gaston, S. J.: Unique Ba t t e ry  Reconditioning Cycle f o r  RCA'S Geo- 
s t a t i o n a r y  S a t e l l i t e s  and I ts  A p p l i c a b i l i t y  f o r  Low Ear th  Spacecraf t ,  
1982 Goddard Space F l i g h t  Center Ba t t e ry  Workshop Proceedings, Page 311. 
3.  Harkness, J. D . :  Evaluat ion Program f o r  Secondary Spacecraf t  C e l l s ,  
Synchronous Orb i t  Tes t ing  of Nickel-Cadmium C e l l s ,  WQEC/C 81-120A, 
1 June 1981, Page 212. 
ACKNOWLEDGEMENTS 
The au tho r s  g r a t e f u l l y  acknowledge M r .  Dave Stewart of RCA Americom f o r  t h e  
va luable  SATCOM s p a c e c r a f t  b a t t e r y  f l i g h t  performance d a t a .  
SPACECRAFT 
SATCOM F1 
SATCOM F 2  
A N I K  B 
SATCOM 3 
SATCOM 4 
SATCOM 5 
SATCOM 6 ( I R )  
SATCOM 7 ( I I R )  
T a b l e  1 
RCA A s t r o  G e o s t a t i o n a r y  Spacecraft O p e r a t i n g  i n  O r b i t  
CELL CAPACITY * 
LAUNCH DATE 
DECEMBER 1 9 7 5  
MARCH 2 6 ,  1 9 7 6  
NOVEMBER 1 9 7 8  
NOVEMBER 1 9 8 1  
JANUARY 1 9 8 2  
OCTOBER 27 ,  1 9 8 2  
A P R I L  11, 1983 
SEPTEMBER 8, 1983 
CUSTOMER (AMP-HOURS) (NAME-PLATE) 
RCA AMERICOM 
RCA AMERICOM 
TELESAT OF CANADA 
RCA AMERICOM 
RCA AMERICOM 
ALASCOM INC 
RCA AMERICOM 
RCA AMERICOM 
* 2 2  CELLS PER BATTERY, 3 BATTERIES PER SPACECRAFT 

MINIMUM AVERAGE 24.0 O SATCoM F1 
BATTERY VOLTAGE 0 SATWM F2 
(VOLTS) 
NUMBER OF ECLIPSE SEASONS 
Figure 2. Minimum average b a t t e r y  vol tage  vs. number of e c l i p s e  seasons. 
MINIMUM AVERAGE CELL 
VOLTAGE (VOLTS) 
0 SATCOM F l  
SATCOM F2 
(NOTE 1) 
PREDICTED VOI 
DEGRADATION 
(NOTE 2) \ 
- 
MINIMUM VOLTAGE REQUIRED FOR FULL PAYLOAD OPERATION 
- - - - - - - - - -  -- 
NOTES: 
1 - SATCOM F2-AFTER ECLIPSE NO. 6,27% DOD DAILY DISCHARGE TERMINATED, 
LOAD REDUCED 5%, DOUBLE-RECOND ITION ING PERFORMED 
2 - SATCOM F2-AFTER ECLIPSE NO. 10, LOAD REDUCED 3% 
- 3 - VOLTAGE DEGRADATION PREDICTIONS BASED ON AVERAGE PERFORMANCE OF 
CRANE BATTERY PACK 207A (OoC) 8 209A (200C), 60% DOD 
NUMBER OF ECLIPSE SEASONS 
Figure 3 .  Minimum average c e l l  vol tage  dur ing  e c l i p s e  vs. number of  
e c l i p s e  seasons.  

0 SATCOM F1 (IN-ORBIT DATA) 
BATTERY VOLTAGE 
(VO LTS) a SATCOM F2 (IN-ORBIT DATA) 
, . 
X GROUP A - 17 AH CELL TEST (62 % DOD BASED ON NAMEPLATE CAPACITY) 
23.0 A GROUP B - 17 AH CELLTEST (72 % DOD BASED ON NAMEPLATE CAPACITY) 
NOTE: BATTERY VOLTAGE FOR GROUPS A & B CALCULATED BY TAKING 
MIDPOINT END-OF-DISCHARGE VOLTAGE OF THE 7-CELL TEST GROUP AND 
22.0 MULTIPLYING BY 22 
1 2 3 4 5 6 7 8 9 10 ?I 12 13 14 15 16 17 
NUMBER OF ECLIPSE SEASONS 
Figure 5. Minimum average b a t t e r y  vol tage  vs. number of e c l i p s e  seasons.  
Kunigahalli, Bowie State  College: Cou1.d you t e l l  me what i s  the 
unique procedure tha t  i s  different  from other procedures? 
Gaston, RCA-Astro: We have a ser ies  of wheel outs in each battery 
and each relay leads to  a reconditioning which actually needs two 
relay contacts to  get the res i s tor  on, ground command a l l  the relays 
cl ick on and a l l  the relays close to  have these crystals  draining 
a l l  in the same time so a l l  are  separate. Each cell  has i t s  own 
res i s tor .  So i t  i s  different  from the others. So you can drain i t  
and not worry about any reversal. 
George, NASAIMarshall Space Flight Center: You said tha t  you applied 
th i s  unique reconditioning method prior to  each eclipse season? 
Gaston, RCA-Astro: Yes. 
George, NASAIMarshall Space Flight Center: How long prior to  each, 
immediately prior? 
Gaston, RCA-Astro: There are always some operation problems. The 
operation problems as follows you got three bat ter ies  and you have 
a fixed time you want to  be sure you cannot you don't  want t o  
recondition a11 three a t  the same time you always want to have some 
bat ter ies  on. So i t ' s  about two to  three weeks prior. I s  t ha t  the 
correct date Stewart? We s t a r t  about 2 t o  3 weeks prior to  s t a r t  
the eclipse so we can recondition the f i r s t  battery - battery 1, 
battery 2 or battery 3 or whichever way you l ike  to. 
George, NASAIMarshall Space Flight Center: So i t  takes approximately 
a week to  recondition the battery - run i t  down and recharge i t .  
Gaston, RCA-Astro: Well giving yourself ,  i t  shouldn't take quite that 
long but jus t  give yourself a l i t t l e  time extra - time in case you 
want t o  t r y  i t  longer or in case you jus t  want to  make sure you are  
ready in time. 
George, NASAIMarshall Space Flight Center: Thank you. 
Armantrout, Lockheed: Steve would you comment on what the plateau 
looks l ike  when you do t h i s  reconditioning and i s  i t  changing with 
time? 
Gaston, RCA-Astro: Well I don't  have i t  here to  show, you're talking 
about the discharge voltage profile.  Right? I s  that  what you are  
referring to? Right? 
Armantrout, Lockheed: Yes. 
A. Gaston, RCA-Astro: I don ' t  have i t  here b u t  when I get chance some 
day we will discuss i t  over the phone. I t h i n k  there a re  some s l igh t  
differences b u t  not very s ignif icant .  I haven't seen them yet .  
COMMENT 
Hendee, Telesat Canada: Really there i s  negligible being of course 
now t h i s  is a res i s t ive  discharge not a constant current or anything 
i t ' s  a res i s t ive  discharge and we see a negligible plateau perhaps 
barely perceptible plateau i f  you were to  go ahead and correct tha t  
back to  say some kind of a constant current discharge. Like to  say 
one other thing. We abuse those ce l l s  tremendously and we have been 
mistreating them on the Anik B discharging several times everyday 
and quite a few things have been running out quite we1 1. The original 
ce l l s  which were allocated to  Anik B were re t rof i t ted  just prior t o  
launch. I can see a t  t h i s  point where a l l  our abuse we're jus t  
s ta r t ing  t o  see a s l igh t  spread in the cel l  of voltages a t  the end 
of discharge whereas the f l igh t  simulation, they are  locked in t i gh t  
as can be. 
Gaston, RCA-Astro: Interesting. 
Hendee, Telesat Canada: One other thing you d idn ' t  mention i s  your 
charge sequence Steve, and tha t  i s  a major difference t o  other people 
as well and I 've  been getting a l o t  of questions a t  Telesat. Well 
what do you think about the sequential charge and as f a r  as I can 
t e l l  actually the sequential charge which we do f ive  minutes f a s t  
charge and ten minutes off .  Actually, i t  seems t o  be beneficial or 
I won't say i t ' s  beneficial l e t  me say that  I see certainly no 
degrading af fec ts  due to  that .  
Gaston, RCA-Astro: Let me jus t  add, Anik B was launched I mentioned 
before t h a t ' s  the table  I was missing was launched November 1978 so 
i t ' s  f ive  years,  ten eclipse seasons. 
Q.  Bell, Hughes Aircraft: Steve, do you have individual cell  voltage 
data on the battery? 
A. Gaston, RCA-Astro: No we do not. We f e l t  a t  tha t  time we don't  need 
i t .  I t ' s  usually when you have a common charging system you are 
concerned about reversing some ce l l s  so you 1 i ke to  go to  some 
threshold value then you would need cel l  voltages, individual ones. 
No we don ' t. 
Q. Bell, Hughes Aircraft: Just  one other question, because i n  some 
laboratory test ing that  we've done depending on the length of the lead 
wire on the res i s tor  with a ser ies  s t r ing  of bat ter ies  sometimes the 
individual cel l  res i s tors  ac t  l ike  a 22 res i s tor  s t r ing across a 22 
cel l  battery. That was the reason why I asked about the individual 
cell  voltages. 
A. Gaston, RCA-Astro: We d o n ' t  have i t  on t h i s  spacecraf t  and i n  t h e  
who1 e ser ies.  
A. B e l l ,  Hughes A i r c r a f t :  Thank you. 


RCA SATCOM Battery in Orbit Performance Update and Accelerated Life Test Results

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