ORS Phase 3 (TacSat-4) 30Ah Li-ion Battery NASA... · Std. Spacecraft Processor ... API Bus Analog...

2011 NASA Aerospace Battery Workshop15-17 November 2011

ORS Phase 3 (TacSat-4)30Ah Li-ion Battery

(A Tale of a Battery’s Adventure from Storage to Flight)

Susie N. LaCavaU.S. Naval Research Laboratory

[email protected]

Thanks to support from:Bob Skalitzky, NRL; J. Christopher Garner, USG;Zoila Forgione, TASC; Paul Beach, Vince Visco,

& Hiroshi Nakahara, Quallion

2011 NASA Aerospace Battery Workshop15-17 November 2011 2

ORS/ISET* Activities

How will it get to Orbit?

What Orbit is it going into?

What Payloads does itneed to support?

How will it be operated?

Make it “Responsive”

Make it “Low Cost”

Generate a Set of Spacecraft Bus Standards, in Sufficient Detail to Allow a Vehicle Manufacturer to Design, Build, Integrate, Test, and Deliver a Low Cost Spacecraft Bus Satisfying an Enveloping Set of Mission Requirements (Launch Vehicle, Target Orbit, Payload, etc.) in Support of a Tactical Operational Responsive Space Mission

Charter

• Government and Industry Team Defined Capabilities• Documents created to capture capabilities include

– Payload Developers Guide (For payload developer independent of Bus Fab)– General Bus Specification (performance capabilities of the Bus)– Software Interface Standards (Ground – Bus and Bus – Payload)

* Operationally Responsive Space/Integrated System Engineering Team


Document Descriptions

Payload Developers Guide- Mechanical, Electrical, Thermal Interface Definition

General Bus Specification- Performance Characteristics,- Launch Vehicle Interfaces, etc.

Software Interface Standards - Space to Ground- Bus to Payload


ISET Standards (Performance)

Parameter ORS Bus Standard*Total Wet Mass 425 kg

Payload Mass 175 kg

Bus Wet Mass 250 kg

Payload Power (Orbital Average) 200 W (700 W Peak)

Pointing Control (3-sigma) 0.05 deg

Pointing Knowledge (3-sigma) 0.01 deg

Slew Rate (deg/sec) Up to 2

Orbit Position Knowledge 30 m (1-sigma)

Payload Data Storage Payload Specific/ 1 Gbyte for Payload Health & Status

Payload Data Transfer Capability [Telemetry D/L]

500kbps to 2Mbps for HEO orbits/ 2Mbps for LEO

Payload Digital Command & Data Interface

RS-422/ HDLC andSpacewire

Switched 28V Power Lines For Payload

3 -> 2 (Critical & Nominal)

Payload Interface Temperature -30°C to +55°C on the Bus, Isolated from the P/L

Bus Propulsion Capability (DeltaV) 300 -> 175 m/s min.

Other Derived Power Rqmts.- 350 Watt-hours in Eclipse for P/L- System Powered off at Launch- Battery Stored Separate from Bus- Battery Installation < ~ 1 day- No charging of Battery once integrated

with the Launch Vehicle

* Services supplied to a Payload


Programmatics• ONR Payload, Flt Ops, Test Bed Sponsor• OFT Bus Sponsor – “Phase 3” Bus Prototype• AFSPC, SMC-12 Provided Launch (M-IV Star 48)• NRL Program Manager• STRATCOM to Assign COCOM Priorities for Use and

Exercises• Multi-Service Participation

Spacecraft and Payload Highlights

TacSat-4 Mission Summary

Ground Equipment• BFT Devices: MTX, Grenadier Brat, Others• COTM: Legacy Radios and Compatible UHF

Wideband Radios• Data-X Buoys and Gnd Sensors >1 Watts• Ground Terminal: One Per 2000 nm Theater• Spacecraft Cmd and Cntrl: Blossom Point, MD

– Additional Coverage From AFSCN– Payload Tasking on SIPRNET-based Virtual

Missions Operations Center (VMOC)

• Satellite [Space Vehicle]: – 444 kg (Incl. Prop and Contingency)– Payload Power: 200-700W– Low HEO (4 hr) Orbit– 1 Year Life

• Payload Capability: – Data-X (>1W) and Blue

Force Tracking (BFT)– Comms-on-the-Move (COTM)

- Legacy Radio and IP Netted Support- MUOS-Like Wideband Capability

Objectives• Demo High Dwell ORS Capability via a HEO Orbit

– Augment Poor/No Coverage Areas• Evaluate and Mature Phase 3, System Level Bus

Standards in Realistic Design, I&T, Launch, and Flight Operations Environment

• Provide TACSAT/ORS Comms-on-the-Move Capability (Legacy, Netted, and MUOS-Like)

• Collect BFT Devices in Underserved Areas• Perform Buoy/Sensor Data-X on Moderate-to-High

Power Transmissions


Spacecraft Block Diagram

Latch Valve Torque Rods

Star Tracker

GPS

Thrusters

Htrs w/Thermostats

TempSensors

PressureSensor

Diplexer

Critical Loads

FwdOmni

AftOmni Mag

422 Cmd/Tlm/Sync

Transponder

Command and Data Electronics

Power Supply Card

Std. Spacecraft Processor

Processor and AttitudeInterface

Attitude and PropulsionInterface Card

Payload Data Handler

Crit Cmd

Power Switching

Cmd & Tlm Interface

Power Sys Elect.

Star TrkrElect.

IMU/IRU

SunSensors

Non-Critical Loads

SADE

Command, Telemetryand Control Card

EPSPlug

LV Sep.

Test

Cou

pler

Switc

h

Battery Charge Control

I&T Test

Payload

UHF Dual Feed

X Band TX Horn

X Band RX Horn

Survival Htr PwrSwitched Payload Pwr

Deployments

Discrete Cmd/TlmI/F

Battery

422 Cmd/Tlm

422 Cmd/Tlm

422 Cmd/Tlm

1 Mbit D/L

Level Cmds

API Bus

AnalogSA Deployment

SolarArraySADA

SolarArray

SADA

SA Deployment

Non-Critical PowerCritical PowerDigital I/F

AnalogRF

Propulsion Power

Battery Interface

LV Sep.

Low Rate D/L

IMU PwrSply

ODTML/UIE Spacewire

TachometerRWA

TachometerRWA

TachometerRWA

RW Elect.

Non-Critical Propulsion Power


EPS Block Diagram

Solar ArraySystem

SADA SADA

PowerSystem

ElectronicsBox

(PSEB)

Battery

SPG

Payload

Bus Loads

NRLNRL/IndustryIndustry

Solar ArraySystem

IMUCU

DIRECTENERGY

TRANSFERTOPOLOGY

LAUNCHEDWITH BATTERY OFF BUS


30Ah Li-ion Battery Required Bus Installation

Battery Radiator Plate

Last Panel Installed Into BusRemovable at Any Time

Battery MaintenanceDone External to Vehicle(Charge/Discharge/Test)

Using Three ExternalConnectors

Battery Mechanically InstalledFully Charged and Then

Connected to Vehicle HarnessVehicle HarnessEgress Port


Battery/Cell Acquisition Approach

• NRL Surveyed the Li-ion Industry for Low Cost Battery Cells• NRL Introduced to Quallion through Joe Stockel

– Quallion Builds State-of-the-Art Li-ion Battery Cells for DoD, NRO, and NASA– Provided Cells at Low Cost in Exchange for Knowledge and Data

• Cooperative Agreement Contract Awarded to Quallion October 2006– Coop-Agreement Instead of CRDA (Cooperative Research & Development

Agreement), Because $$ Provided to Quallion for Cells• Quallion Built, Tested, and Delivered 40 Cells to NRL On or Before 15 August

2007 (in Batches so NRL Can Begin Battery Build)• NRL to Provide Quallion With Design “Know-How” for the Build and Qualification

of Battery Assembly Including Drawings, Procedures, Test Plans, etc.• Quallion Observed Construction and Testing, and Will Receive On-Orbit Data• Cell Selected: QL015KA (15Ah)• Battery Topology Selected: 8S2P


QL015KA 15Ah Li-ion Cell Detail

• Manufacturer: Quallion• Chemistry: LiNiCoAlO• Nameplate Capacity: 15 Amp-Hours*• Part Number: QL015KA• Voltage Range: 0.0 - 4.1 Vdc• Cell Mass: 460 grams• Cell Cover Material: SS• Cell Case Material: SS• Cell Dimensions: 3.5” x 2.0” x 2.5”• Energy Density: 121 Whr/kg* When Charged to 4.1 Vdc and Discharged to 2.7 Vdc

• Cell Level Tests Performed by Quallion– DC Internal Resistance Test Pre-

and Post-Testing– C/5 Cycling at 0, 25, and 40°C:

Cycle Between 3.0 and 4.1 Vdc(With Taper Charge) Three Times; Evaluate Capacity

– Self Discharge Test; When Cells Are Fully Charged, Let Stand for 72 Hours, Then Evaluate the Drop in Cell Potential

– C/5 Cycling at 0, 25, and 40°C After Storage at 50% SOC over 90 Days; Evaluate Capacity; Calculate Capacity Loss If Any

– X-Ray Photographs and Leak Test


Quallion QL015KA 15Ah Li-ion CellElectrical Performance Data (Life Data)

TOTAL STANDARD CAPACITY MEASUREMENT AND DC RESISTANCE

8

9

10

11

12

13

14

15

16

0 2000 4000 6000 8000 10000 12000 14000 16000 18000

Cycle Number

Cap

acity

(Ah)

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

DC

Res

ista

nce

(ohm

s)

60% DOD LEO CyclingQuallion 15 AhTest Temperature 23 °C

Total Standard Capacity

DC Resistance


Quallion QL015KA 15Ah Li-ion Cell Electrical Performance Data

QUALLION QL015KA 15 AH LITHIUM-ION CELL CHARACTERIZATIONAT C RATE OF DISCHARGE

2.500

2.700

2.900

3.100

3.300

3.500

3.700

3.900

4.100

4.300

0.00 10.00 20.00 30.00 40.00 50.00 60.00TIME (minutes)

Cel

l Vol

tage

(Vdc

)

-16.000

-14.000

-12.000

-10.000

-8.000

-6.000

-4.000

-2.000

0.000

Cur

rent

(Adc

)

Cell VoltageDischarge Current

--> greater than 60% DODVcell(DOD=60%) = 3.385 Vdceclipse load: about 25 Amps

last update: 25 November 2006


30Ah Li-ion Battery Electrical Block Diagram

• Wiring Per SB-EP-0010• Box ID: A015• Cell-to-Cell Interconnects Using Custom

Flexible Bus Bars Manufactured by Storm Copper

– 2 Sizes Required: Parallel, Series Connections

– Copper Braid in between seamless copper bars that are nickel-flashed and gold-plated

• 4 Temperature Sensors – 2 AD590 sensors for Telemetry– 2 LTN11 sensors for Ground Test

• 3 Circular Connectors: D38999 Series IV– J1 Power: 4 +, 4 Rtn lines – J2 Telemetry (Voltages, Temps)– J3 Ground Charge – Cell Balance


30Ah Li-ion Battery Packaging

Virtual30Ah Cell

Tie Rods forCompression

(Mechanical & Thermal)

Cover, ConnectorsNot Shown

ThermalWalls

SupportStructure

CellInterconnects


30Ah Li-ion Battery Thermal Analysis - Heat Dissipation

STANDARD BUS 30 AMPERE-HOUR LITHIUM-ION BATTERY HEAT GENERATION DURING DISCHARGE AT 25 AMPS

0

20

40

60

80

100

120

0 500 1000 1500 2000 2500 3000

TIME (Seconds)

HEA

T G

ENER

ATI

ON

(Wat

ts)

Pinakin, Vtn Methods Averaged

-->greater than 60% DOD

last update: 25 November 2006


30Ah Li-ion Battery Thermal Analysis

Baseline Deviations:

• 2610 Second Transient Calculation (43.5 Minutes), 10 Second Time Step

• Transient Power Dissipation Curve (Pinakin, Vtn Methods Averaged) Supplied by 8244

• Power Group on 11/30/2006

• No Shims

• Walls 1 and 5 are 0.075 in. Thick

• Walls 2 and 4 are 0.225 in. Thick

• Wall 3 is 0.300 in. Thick• Maximum Cell Temperature Delta (End of Transient) = 4.36 °C• Cell Thermal Profiles Are Matched Well From Cell to Cell• Less Than 3 °C Temperature Delta Within Planes Parallel to the Baseplate From Virtual Cell to Virtual Cell, and Within a Cell


Photos of Battery

Battery Mass:29.6 lbs.

Battery Size:10-31/32” x 8-26/32” x 7-1/16”


Battery Tests/Charging Operations

• Battery was Tested per NCST-TPL-SB008• Tests were Performed between 21 March 2008 and 04 May 2008

– Safe-to-mate– Insulation Resistance (Pre- and Post- Random Vibe)– Capacity Tests

3 Cycles @ 10°C, 20°C, and 30°C 2 Cycles @ 10°C post-Random Vibe & TVAC

– Orbital Cycling (2 days → 12 cycles)– Random Vibration– TVAC (1 day → 6 cycles @ 10°C, 20°C, 30°C, and then 20°C again)– ALL Tests PASSED

• System Level Tests Supported by Battery– Vibration– EMI– Magnetic Dipole Moment

• Charge Control– All Charging Done by Battery Charging/Test System– Charging Can Be Done in Parallel with Bus Testing if Battery is Installed

• Battery Placed in Storage in Battery Lab Separate from Bus at Room Temperature from May 2008 to April 2009


Battery Test/Charge Control Approach

Cell Cell

Cell Cell

Cell Cell

Cell Cell

Cell Cell

Cell Cell

Cell Cell

Cell Cell

GRND

TEST

J3

RedundantBattery

CellBypass*

TELEMETRY

J2

T

T

POWER J1

POWER J1

BatteryChargeRackandComputerMonitor*

I-Mon

*Modified U/S

Controls Charge End PointProtects Against Over-Charge


Capacity Test @ 10°C

SBEP0050 SN002 CHARACTERIZATION DURING CAPACITY TEST AT 10 DEG C 20080411 CYCLE 3

2.000

2.200

2.400

2.600

2.800

3.000

3.200

3.400

3.600

3.800

4.000

4.200

4.400

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900

Time Elapsed (Minutes)

Volta

ge (V

dc)

-8.000

-6.000

-4.000

-2.000

0.000

2.000

4.000

6.000

8.000

Cur

rent

(Adc

)

Cell 8 V

Cell 7 V

Cell 6 V

Cell 5 V

Cell 4 V

Cell 3 V

Cell 2 V

Cell 1 V

Current




2.000

2.200

2.400

2.600

2.800

3.000

3.200

3.400

3.600

3.800

4.000

4.200

4.400

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700


Volta

ge (V

dc)

-8.000

-6.000

-4.000

-2.000

0.000

2.000

4.000

6.000

8.000

Cur

rent

(Adc

)

Cell 8 V

Cell 7 V

Cell 6 V

Cell 5 V

Cell 4 V

Cell 3 V

Cell 2 V

Cell 1 V

Current




2.000

2.200

2.400

2.600

2.800

3.000

3.200

3.400

3.600

3.800

4.000

4.200

4.400

700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500


Volta

ge (V

dc)

-8.000

-6.000

-4.000

-2.000

0.000

2.000

4.000

6.000

8.000

Cur

rent

(Adc

)

Cell 8 V

Cell 7 V

Cell 6 V

Cell 5 V

Cell 4 V

Cell 3 V

Cell 2 V

Cell 1 V

Current


Battery Install Photos20 July 2010 & 06 August 2010


Battery Tests/Charging OperationsStorage #1

• May 2008 to April 2009 (~10 months) – Battery in storage in Battery Lab at Room Temperature separate from Bus

• 01-05 May 2009 – Battery tested per NCST-TPL-SB008

– Capacity Test (3 Cycles at Room Temperature (25 ± 5°C))

• 06 May 2009 – Battery installed in Bus!

– Capacity Test (1 Cycle at Room Temperature (25 ± 5°C))

• Observation Noted

– Hardly any loss over the 10 months in storage in cells: ~0.002 Vdc max

• 04 August 2009 – Launch delayed…

– Battery physically de-mated and removed from Bus and put back in storage at Room Temperature in Battery Lab



• August 2009 to July 2010 (~11 months) – Battery in Storage in Battery Lab at Room Temperature separate from Bus

• 18-22 March 2010 – Battery tested per NCST-TPL-SB008


– No capacity loss observed during 7.5 months in storage

• 20 July 2010 – Battery installed in Bus!

• 17-19 August 2010 – Battery tested per NCST-TPL-SB008


– No capacity loss observed since last capacity test in March (5 months)

• 31 August 2010 – Launch delayed again…

– Decision made to keep Battery installed in Bus; electrically de-mated

– Entire Bus placed in Storage


August 2009 – July 2011 StorageCell VoltagesSBEP0050 SN002 CharacterizationStorage - August 2009 to July 2011

Monthly Checks

3.3000

3.3500

3.4000

3.4500

3.5000

3.5500

3.6000

3.6500

3.7000

17-A

ug-2

009

11-S

ep-2

009

06-O

ct-2

009

31-O

ct-2

009

25-N

ov-2

009

20-D

ec-2

009

14-J

an-2

010

08-F

eb-2

010

05-M

ar-2

010

30-M

ar-2

010

24-A

pr-2

010

19-M

ay-2

010

13-J

un-2

010

08-J

ul-2

010

02-A

ug-2

010

27-A

ug-2

010

21-S

ep-2

010

16-O

ct-2

010

10-N

ov-2

010

05-D

ec-2

010

30-D

ec-2

010

24-J

an-2

011

18-F

eb-2

011

15-M

ar-2

011

09-A

pr-2

011

04-M

ay-2

011

29-M

ay-2

011

23-J

un-2

011

18-J

ul-2

011

Date (Actual)

Cel

l Vol

tage

(V)

Cell 1 (V)

Cell 2 (V)

Cell 3 (V)

Cell 4 (V)

Cell 5 (V)

Cell 6 (V)

Cell 7 (V)

Cell 8 (V)



• August 2010 to February 2011 (~5 months) –Battery in Storage installed in Bus

• 08 February 2011 – Bus pulled out of Storage!

– Battery Pack and Cell Voltages Measured

No change since placed in storage

• 01 March 2011 – Bus, Payload, and I&T Crew left NRL for Kodiak, AK!!!

• 02 March 2011 – Arrived at Kodiak, AK!!!

• Launch Date: 05 May 2011



• 28-30 March 2011 – Battery tested per NCST-TPL-SB008. Too cold for Kodiak bears to be out and about…


– No capacity loss observed

• Final Charge on Battery Scheduled for 15 April 2011!

• 07 April 2011 – Launch was placed on-hold due to issues related to the Taurus fairing failure and Minotaur manifest ordering

– SV placed in storage in current position in the KLC PPF…

• 31 May 2011 – Received word that Minotaur LV approved to return to flight. TacSat-4 to launch 3rd in line after ORS-1 and HTV-2B. Yay!

• 21-23 June 2011 – Battery tested per NCST-TPL-SB008. Saw one Kodiak bear on way to KLC.


– No capacity loss observed

– Observed an “issue” with GSE with third cycle on charge

Resolved on 13 July 2011 - GSE verified to be operational


Battery Capacity ComparisonSB-EP-0050 SN002 Battery Capacity Comparison

May 2009 through June 2011Voltage vs. Capacity

20.0000

22.0000

24.0000

26.0000

28.0000

30.0000

32.0000

34.0000

0.000 5.000 10.000 15.000 20.000 25.000 30.000 35.000

Capacity (Ah)

Pack

Vol

tage

(V)

Battery Capacity 2010-03 (March)

Battery Capacity 2009-05 (May)

Battery Capacity 2010-09 (August)

Battery Capacity 2010-12 (December)

Battery Capacity 2011-03 (March)

Battery Capacity 2011-06 (June)

31.024 Ah

30.510 Ah

May 2009: Discharge took 308 Minutes at 6A. (Baseline)

30.882 Ah

August 2010: Discharge was 2 Minutes Shorter.March 2010: Discharge was 6 Minutes Shorter.

December 2010: Discharge was 3 Minutes Shorter.

30.727 Ah

30.641 Ah

March 2011: Discharge was 5 Minutes Shorter. 30.686 AhJune 2011: Discharge was 4 Minutes Shorter.


Current Status

• Final Battery Charge Performed 07 September 2011

• Launch Date: 27 September 2011

Battery


SV Photos


Launch Photos


Day in the LifeThermal/Power/Attitude

• Satellite Goes Through Six, 4 Hour Orbits Per Day• Apogee Operations:

– Payload Will Pass Over Primary Theater at Apogee Three Consecutive Passes

– Next Three Passes Spacecraft Will Not Pass Over Primary Theater – Payload Will Operate for Up to 2 Hours During Each Pass Over

Primary Theater – Payload Will Operate During Non-Primary Theater Passes to Service

Additional Theaters– Mission ConOp Includes Servicing Multiple Theaters in a Given Day,

Within Spacecraft Limits– Typical Payload Operations Per Pass Over Primary Theater

10 Legacy Comms Channels for 1 Hour, 24 Minutes Or 6 Legacy Comms Channels for 2 Hours Or Blue Force Tracking and Wideband Comms for 2 Hours Or Data-X for 2 Hours

– Payload Will be Targeted to a Specific Point in Theater During Payload Operations Nominally Targeted at Ground Terminal

• Non-Apogee Operations:– When Payload Is Off, Spacecraft Will Be Aligned -Z to the Sun

Was Selected As Best Attitude for Bus Thermal Subsys Allows Solar Panels Uninterrupted Access to Sun

• BP Contacts As Available - 3-4 per Day


Orbit Track


Post-Launch Battery Performance Data

TacSat-4 30Ah Li-ion Flight Battery Performance SB-EP-0001 S/N002

Battery Voltage and Current

30.000

30.500

31.000

31.500

32.000

32.500

33.000

33.500

9/27/11 16:48:00 9/27/11 17:02:24 9/27/11 17:16:48 9/27/11 17:31:12 9/27/11 17:45:36 9/27/11 18:00:00 9/27/11 18:14:24 9/27/11 18:28:48 9/27/11 18:43:12

Date & Time (Zulu)

Volta

ge (V

)

-15.000

-10.000

-5.000

0.000

5.000

10.000

15.000

20.000

Curr

ent (

A)

BATT VMON BATT IMON


Post-Launch Cell Performance Data

TacSat-4 30Ah Li-ion Flight Battery PerformanceSB-EP-0001 S/N002

Cell Voltages

3.800

3.850

3.900

3.950

4.000

4.050

4.100

4.150

9/27/11 16:48:00 9/27/11 17:02:24 9/27/11 17:16:48 9/27/11 17:31:12 9/27/11 17:45:36 9/27/11 18:00:00 9/27/11 18:14:24 9/27/11 18:28:48 9/27/11 18:43:12

Date & Time (Zulu)

Volta

ge (V

)

VC 1

VC 2

VC 3

VC 4

VC 5

VC 6

VC 7

VC 8


Post-Launch Battery Performance Data

TacSat-4 30Ah Li-ion Flight Battery PerformanceSB-EP-0001 SN002

Battery Voltage & Current

32.000

32.100

32.200

32.300

32.400

32.500

32.600

32.700

32.800

32.900

33.000

10/7/11 23:16:48 10/8/11 4:04:48 10/8/11 8:52:48 10/8/11 13:40:48 10/8/11 18:28:48 10/8/11 23:16:48

Date & Time (Zulu)

Volta

ge (V

dc)

-0.100

0.000

0.100

0.200

0.300

0.400

0.500

Curr

ent (

A)

BATTERY_VMON BATTERY_IMON


Post-Launch Cell Performance Data

TacSat-4 30Ah Li-ion Flight Battery PerformanceSB-EP-0001 SN002

Cell Voltages

4.000

4.010

4.020

4.030

4.040

4.050

4.060

4.070

4.080

4.090

4.100

10/7/11 23:16:48 10/8/11 4:04:48 10/8/11 8:52:48 10/8/11 13:40:48 10/8/11 18:28:48 10/8/11 23:16:48

Date & Time (Zulu)

Volta

ge (V

dc)

VC1 VC2 VC3 VC4 VC5 VC6 VC7 VC8


Eclipse Projection

ORS Phase 3 (TacSat-4) 30Ah Li-ion Battery NASA... · Std. Spacecraft Processor ... API Bus Analog...

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Transcript of ORS Phase 3 (TacSat-4) 30Ah Li-ion Battery NASA... · Std. Spacecraft Processor ... API Bus Analog...