Performance of AEA 80 Ah Battery Under GEO Profile

N. Russel, D. Curzon, and K. Ng(AEA Technology)L. Lee and G. Rao

(NASA/GSFC)

GSFC

https://ntrs.nasa.gov/search.jsp?R=20080015790 2018-11-03T07:13:46+00:00Z

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GSFCContents• AEA Geosynchronous Earth Orbit (GEO) Life Testing• AEA/Goddard Space Flight Center (GSFC) 20 Ah Battery• AEA/GSFC 80 Ah Battery• Solar Dynamic Observatory (SDO) Life Test

– Real-Time Profile and Setup

• Test Results• Correlation

– AEA Fade Tool– Long Term Projection

• Conclusions

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GSFCAEA GEO Life Testing

AEA initiated cycling and calendar life tests over 6 years ago

Accelerated GEO cycling tests with no solstice period

GSFC directed a real-time life test at battery level at AEABattery design based on an existing module previously qualified for GSFC

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GSFCAEA/GSFC 20 Ah Battery• Assembled using 128 individual SONY 18650 1.5

Ah cells • Arranged in a S-P system topology• 16 parallel strings each containing 8 cells in series• 8 cells in series string provide battery voltage (20 to

33.6 V)• Battery provides 20 Ah capacity when discharged at

10 A to 24 V at 20ºC • Six thermistors for temperature telemetry• Three multi-pin connectors (Power, Flight

Telemetry and Ground Telemetry)

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GSFCAEA/GSFC 80 Ah Battery• 40 Ah Test module assembled using

four of the standard 8 x 8 battery blocks

• Battery block uses qualified design from 20 Ah units

•Each block contains 64 cells•Total of 256 cells per test module

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GSFCSDO Life Test: Overview

• Real time GEO life testing including solstice and eclipse seasons

• Capacity measurements performed only at the start of each eclipse season– Before first eclipse season each year both AEA* and

GSFC** capacity measurements performed– Before second eclipse season each year an extra AEA

capacity measurement is performed

* C/10 charge to 33.6V and C/10 discharge to 20.0V**C/10 charge to 33.6V clamp with a taper current to C/100 and C/2 discharge to 24.0V

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GSFCSDO Life Test: Overview – cont’d

• Eclipse Regime– Charge at 4A to 33.35V clamp with a taper to 0.1 A, followed by

0.1A constant current until end of the charge period– Maximum State-of-Charge (SOC) 98% day 1 and day 42– Minimum SOC 28% days 21-23– Discharge current 48A

• Solstice Regime– 140 days– Voltage clamp at 32.3V (72% SOC)– Fully charged before prior to commencement of eclipse season

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GSFCSDO Life Test: Real-Time Profile

0102030405060708090

100

0 50 100 150 200 250 300 350 400Day

Dis

char

ge D

urat

ion

(min

)

Eclipse 1 Eclipse 2Solstice 1 Solstice 2

AEA and GSFC Capacity

Measurement

AEA Capacity Measurement Only

AEA and GSFC Capacity

Measurement

Eclipse 3

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GSFCSDO Life Test Setup

+ve connectors

-ve connectors

Parallel connection of harnesses

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GSFCTest Results• AEA Standard Capacity Measurement (SCM) (C/10 charge and discharge) =

91.41 Ah• CGSFC (C/10 charge & taper to C/100, C/2 discharge) = 83.02 Ah• CTOTAL = 97.76 Ah

GSFC 80Ah SDO GEO Lifetest Battery

-100

-80

-60

-40

-20

0

20

40

60

80

100

0 5 10 15 20 25 30 35Time in hours

CU

RR

EN

T (A

) & C

APA

CIT

Y (A

h)

15

20

25

30

35

40

VO

LT

AG

E (V

)

Cap. [Ah] Current [A] Voltage [V]

AEA CapacityCharge 91.47Ah

Discharge 91.41Ah

GSFC CapacityCharge 94.95Ah

Discharge 83.02Ah

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GSFCTest Results: Voltage

Completed to date nominal three seasons

Note rising voltage towards end of charge−True taper charge to very low current not possible with test equipment used

−Min current without a specific ‘rest’ mode is 0.1 A

−Therefore battery charged to 33.35 V then held at 0.1 A current for remaining duration

−33.35 V calculated to ensure battery remains below 33.6 V at end of charge for worst case (minimum discharge)

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GSFCTest Results: Voltage First Eclipse Season Profile

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26

27

28

29

30

31

32

33

34

35

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

Time (Day)

Vol

tage

(V

)

0

10

20

30

40

50

60

70

80

90

100

Dis

char

ge D

urat

ion

(min

)

Voltage [V] Discharge Duration

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GSFCTest Results: VoltageProfiles for Maximum Depth-of-Discharge (DOD), 72%, for the Three

SeasonsFirst Eclipse (72 min)

27

28

29

30

31

32

33

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20.0 20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.8 20.9 21.0

Time (Day)

Vol

tage

(V

)

Second Eclipse (72 min)

27

28

29

30

31

32

33

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20.0 20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.8 20.9 21.0

Time (Day)

Vol

tage

(V

)

Third Eclipse (72 min)

27

28

29

30

31

32

33

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20.0 20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.8 20.9 21.0

Time (Day)

Vol

tage

(V

)

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GSFCTest Results: Current• Logged current shows four stages per orbit:• Main constant current charge at 4 A• Taper region when voltage clamped at 33.35 V• Limiting 0.1 A current for remaining duration of

charge• 48 A discharge current results in a peak of 57.6 Ah

(equivalent to 72% DOD of CGSFC)

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GSFCTest Results: CurrentProfile for the Eclipse Season

-60

-50

-40

-30

-20

-10

0

10

20

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

Time (Day)

Cur

rent

(A

)

0

10

20

30

40

50

60

70

80

Dis

char

ge D

urat

ion

(min

)

Current [A] Discharge Duration

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GSFCTest Results: Temperature• 1 thermistor at the centre of each block

– represents maximum cell temperature• On following plot ‘spike’ temperature rises during the discharge

periods– Peak cell temperature approx 30°C

• Variation in temperature during charge follows repeating pattern:– Initially endothermic (temp falls below interface (I/F)) – Then exothermic (temperature rises 1 to 2°C)– Then cells cool back towards I/F temperature near end of charge

when current tapers and dissipation reduces– Small variation in I/F temperature due to thermal control limits

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GSFCTest Results: TemperatureProfile for the Eclipse Season

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22

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25

26

27

28

29

30

31

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

Day

Cel

l Tem

pera

ture

(deg

C)

0

10

20

30

40

50

60

70

80

90

100

110

120

130

Dis

cahr

ge D

urat

ion

(min

utes

)

MODULE 1-1 ('C)

MODULE 1-2 ('C)

MODULE 1-3 ('C)

MODULE 1-4 ('C)

MODULE 2-1 ('C)

MODULE 2-2 ('C)

MODULE 2-3 ('C)

MODULE 2-4 ('C)

Discharge Duration

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GSFCTest Results: Solstice GSFC GEO Battery Voltage and Charge Current 2nd solstice

15.00

20.00

25.00

30.00

35.00

40.00

23/02/2004 14/03/2004 03/04/2004 23/04/2004 13/05/2004 02/06/2004 22/06/2004 12/07/2004 01/08/2004

DATE

VO

LT

AG

E (V

)

0

1

2

3

4

5

6

7

8

9

10

11

CH

AR

GE

CU

RR

EN

T (m

A)

Battery Volltage (V) Battery Current (mA)

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GSFCCorrelation: AEA Fade Tool

• AEA life test program has accumulated over 40 million cell hours including 6 years calendar life

• Intended to simulate Low Earth Orbit (LEO), Geosynchronous (GEO), Medium Earth Orbit (MEO), Geosynchronous Transfer Orbit (GTO), Interplanetary and Planetary Lander scenarios

• This data, combined with understanding of cell level chemical processes has been incorporated into AEA fade tool

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GSFCCorrelation: AEA Fade Tool - cont’d

• Simple Excel based user interface• Each phase defined by temperature, duration, number of

cycles, DOD, state of charge

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GSFCCorrelation: AEA Fade Tool - cont’d

17181920212223242526

0 200 400 600 800 1000Time (min)

Bat

tery

Vol

tage

(V)

-3-2-10123456

Cha

rge/

Dis

char

ge C

urre

nt (A

)

Measured Battery Terminal Voltage BEAST2003 Predicted Terminal VoltageMeasured Discharge current Measured Charge CurrentBEAST2003 Inported Current Data

PROBA In-Orbit Battery Performance 12/ 06/ 04

Phase 1081.0%Year 2:

Non-Op 1

Phase 981.4%

Year 2: Orbit Type 30 - 160

Phase 883.1%

Test Pause

Phase 783.2%

Year 1: Orbit Type 640 - 665

Phase 683.8%Year 1:

Non-Op 2

Phase 584.3%

Year 1: Orbit Type 358 - 470

Phase 485.4%Year 1:

Non-Op 1

Phase 386.1%

Year 1: Orbit Type 30 - 160

Phase 295.5%Cruise

Phase 198.1%AIT

0

20

40

60

80

100

120

0 200 400 600 800 1000 1200 1400 1600Mission Duration (Days)

Cap

acity

(%)

Proba Mission Data

Mars Express Real Time Lifetest Data

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GSFC

End of Eclipse Season 1

95.0%Start of Eclipse

Season 292.8%

Start of Eclipse Season 2

89.0%

0

20

40

60

80

100

120

0 50 100 150 200 250 300 350 400Mission Duration (Days)

Cap

acity

(%)

Fade Tool Predictions

Correlation: AEA Fade Tool - cont’d

End of Eclipse Season 1

95.0%Start of Eclipse

Season 292.8%

Start of Eclipse Season 2

89.0%

0

20

40

60

80

100

120

0 50 100 150 200 250 300 350 400Mission Duration (Days)

Cap

acity

(%)

Start of Eclipse Season 2

96%

Start of Eclipse Season 2

93%

Start of Eclipse Season 1

102%Actual Data

Fade Tool Predictions

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GSFCCorrelation: Long Term Prediction

0 500 1000 1500 2000 2500 3000 3500

Mission Duration (Days)

Cap

acity

(%)

10 Year MissionXX% Capacity

Remaining

5 Year MissionXX% Capacity

Remaining

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GSFCConclusions

• To date completed three SDO real-time eclipse seasons

• Sony 18650HC has a low rate of capacity fade under GEO cycling regime

• Real time test results correlate with accelerated GEO lifetest data and AEA capacity fade prediction tool

• This data, together with other AEA test data, justify the SDO Project decision to baseline Lithium-Ion chemistry for the spacecraft battery.

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GSFCAcknowledgements