Lithium-Ion Battery Testing Under ECSS-E-HB-20-02A

Lithium-ion batteries provide energy storage for spacecraft when electrical power from solar arrays is unavailable or insufficient. This can occur during eclipse periods, payload peak demand, initial deployment, emergency conditions or particular spacecraft manoeuvres. Battery testing is therefore required to understand whether the selected cell or battery can meet the performance, environmental, life and safety needs of the intended mission. 

ECSS-E-HB-20-02A is a practical handbook for lithium-ion cell and battery testing during the development and qualification of space equipment and systems. It brings together test experience, know-how and lessons learned from the European space community. Its principal subjects are test conditions, required information, test methods, reporting and good practice. 

Engineers should care because acceptable beginning-of-life performance is not enough. The effect of cycling, time, temperature, state of charge and mission operating profiles must be understood sufficiently to support predictions of in-service and end-of-life behaviour. The handbook therefore emphasises comprehensive test data, controlled test conditions and documented analysis.

The handbook does not provide a single universal battery qualification recipe. Its recommendations must be applied within the relevant project requirements, mission environmental profile, battery design, supplier information and approved verification strategy.

ECSS-E-HB-20-02A is an ECSS engineering handbook providing guidance on the testing of lithium-ion cells and batteries and the associated generation of test documentation. Its stated purposes are to:

• Summarise relevant characterisation tests.

• Provide guidance for lithium-ion battery testing.

• Provide guidance for test-related documentation.

• Give an overview of appropriate test methods.

• Present recognised good practice. 

Its engineering purpose is to improve the quality, consistency and usefulness of battery test programmes.

It helps project teams define:

• What is being tested.

• Why the test is required.

• Which conditions apply.

• What measurements must be taken.

• How results and anomalies should be documented.

• How test evidence contributes to understanding battery suitability.

The handbook considers different test articles, including individual cells, strings, building blocks, modules and complete batteries. This matters because evidence obtained at one level is not automatically representative of performance at another level.

Characterisation and life-test data help engineers understand capacity, energy, resistance, rate capability, ageing and operational limitations.

Lot acceptance and wear-out testing can help identify changes associated with materials, manufacturing processes or cell lots.

The handbook addresses battery health or capacity checks before and after the AIT campaign and recommends minimising unnecessary use of the flight battery during AIT.

Test plans, procedures, reports, raw data, analysis and nonconformance records form part of the verification evidence.

Evidence from electrical, environmental, life and safety testing contributes to the assessment of whether the battery is suitable for the defined mission. It does not independently constitute flight approval.

A spacecraft battery can meet its initial capacity requirement and still present mission risk through:

• Capacity fade.

• Increasing internal resistance.

• Poor low-temperature performance.

• Unexpected self-discharge.

• Mechanical vulnerability.

• Electrolyte leakage.

• Inadequate cycle life.

• Unsafe response to electrical abuse.

• Failure of protective devices.

The handbook addresses these risks through electrical characterisation, environmental testing, life testing and safety testing. [ECSS-E-HB-…ctober2015 

The handbook supports the implementation of relevant ECSS requirements, but it is not a substitute for the applicable standards or customer specification. It references ECSS documents covering testing, the space environment, electrical and electronic engineering, storage and handling, and material outgassing. It also references transport and crewed-space battery safety documents. 

Confidence comes from controlled, traceable evidence. The handbook expects test documentation to identify the test item, test conditions, test criteria, methods, equipment, instrumentation, results, analysis and related nonconformances. 

Battery performance can change with calendar age, charge-discharge cycling, temperature, depth of discharge, state of charge and operating profile. Life testing and representative mission-profile testing provide data that can support battery sizing and end-of-life performance predictions.

The handbook groups testing into four principal technical areas, supported by documentation and handling guidance.

The handbook covers:

• Standard capacity and energy measurement.

• Internal resistance measurement.

• AC impedance measurement.

• Self-discharge testing.

• Charge-retention testing.

• Rate-capability assessment.

• Cell electromotive-force measurement.

• Battery magnetic-moment measurement.

• Corona testing for high-voltage batteries.

These tests establish baseline performance and help identify changes following environmental exposure, life cycling or storage.

Results are condition-dependent. Capacity, energy and resistance figures have limited meaning unless charge method, discharge rate, temperature, voltage limits, rest periods, state of charge and previous test history are recorded.

Environmental testing includes:

• Low-level sine vibration.

• High-level sine vibration.

• Random vibration.

• Shock.

• Thermal vacuum.

• Electrolyte leak testing.

• Cell-can hermeticity testing.

• Radiation testing. 

Mechanical testing is intended to validate aspects of design and manufacture against the mission environment. When cells or subassemblies are tested in a representative fixture rather than a complete battery, the fixture and input levels must account for the intended installation and possible structural amplification.

Thermal vacuum testing is applied against the mission profile. Relevant parameters include operational and non-operational temperature limits, transition rates, dwell periods, cycle count, pressure and electrical cycling conditions. The handbook specifically states that battery cells should not be baked out because doing so can damage the test item. Word]

The handbook covers:

• Calendar or survivability testing.

• Constant depth-of-discharge cycling.

• Constant depth-of-discharged-energy cycling.

• Mission-profile cycling.

• GEO-related profiles.

• LEO-related profiles.

• Real-time testing.

• Accelerated testing.

• Wear-out testing.

Life testing is used to understand long-term degradation and generate factors for battery sizing and performance calculations. The handbook warns, in effect, that acceleration must be technically justified because excessive temperature, current or other acceleration can introduce unrealistic ageing and over-test the cell.

The handbook addresses:

• Overcharge.

• Overdischarge.

• External short circuit.

• Internal-short-circuit considerations.

• Vent pressure.

• Burst pressure.

• Protective-device operation.

The identified hazards include venting, fire, burst, explosion and electrolyte leakage. Safety testing is intended to characterise behaviour and protective features. It does not mean that every listed abuse test is automatically appropriate for every assembled flight battery.

The handbook also considers:

• Storage conditions.

• Maintenance conditions.

• Shelf life.

• Safe handling.

• Transportation.

• Battery checks during AIT.

• Minimising use of flight batteries.

• Open-circuit-voltage monitoring.

Transport-related testing is connected to the UN Manual of Tests and Criteria, subsection 38.3, rather than being replaced by this ECSS handbook.

The handbook references:

• ECSS-S-ST-00-01, ECSS system terminology.

• ECSS-E-ST-10-03, space engineering testing.

• ECSS-E-ST-10-04, space environment.

• ECSS electrical and electronic engineering requirements.

• ECSS-Q-ST-20-08, storage, handling and transportation of space hardware.

• ECSS-Q-ST-70-02, thermal-vacuum outgassing testing of space materials.

Only documents genuinely applicable to the specific project and test scope should be listed in the final compliance baseline.

Tailoring should address:

• Mission orbit and duration.

• Thermal environment.

• Radiation environment.

• Launch loads.

• Eclipse and power-demand profile.

• Cell chemistry and construction.

• Battery architecture.

• State of charge during testing.

• Qualification, acceptance or protoflight philosophy.

• Test-item representativeness.

• Available heritage evidence.

• Customer and launch-provider requirements.

Tailoring does not mean quietly removing difficult tests. Each inclusion, modification or deletion should be justified and approved through the project’s requirements process.

Customer requirements may supplement or exceed the handbook’s recommendations. The controlling position should be established in the test specification and agreed documentation, not assumed from the handbook title.

• Establish the applicable requirements and document baseline.

• Define the verification objective.

• Identify whether the activity supports development, lot acceptance, qualification, acceptance or another purpose.

• Define the test item and its configuration.

• Determine required environmental and electrical profiles.

• Establish measurable success and failure criteria.

• Approve the test specification and procedure.

• Confirm test-item configuration.

• Confirm state of charge and battery history.

• Review hazards and protective measures.

• Verify instrumentation range, accuracy and calibration.

• Confirm sensor positions and data-acquisition settings.

• Complete the test readiness review.

• Record pre-test condition and baseline measurements.

• Apply the approved sequence and environment.

• Monitor voltage, current, temperature and other required parameters.

• Record interruptions, deviations and anomalies.

• Retain raw data.

• Prevent uncontrolled changes to the test article or set-up.

• Compare results against approved criteria.

• Evaluate trends and changes from baseline.

• Assess anomalies and nonconformances.

• Confirm whether retesting is technically justified.

• Check whether the test remains representative.

• Issue the test report.

• Include test configuration, conditions, data and analysis.

• Close or formally disposition nonconformances.

• Update the verification evidence.

• Record limitations and outstanding actions.

The handbook states that test reports should recall the test items and conditions, provide test data and analysis, and describe related nonconformance reports and their disposition.

Measure usable charge and energy under defined temperature, charge, discharge and voltage conditions. Repeat measurements where required to identify degradation following testing.

Characterise resistance and impedance under defined state-of-charge and temperature conditions. Use consistent methods when comparing results across test stages.

Apply appropriate sine, random vibration and shock environments. Use representative mechanical interfaces and monitor for changes before and after significant exposures.

Apply mission-relevant vacuum and temperature conditions while controlling electrical operation, dwell periods, transition rates and cycle count.

Evaluate degradation caused by storage, calendar ageing and charge-discharge cycling. Where accelerated testing is used, establish whether the acceleration mechanism remains representative.

Characterise response to overcharge, overdischarge, short circuit, pressure and protective-device activation using a specific hazard-controlled procedure.

Assess more than pass or fail. Review:

• Capacity loss.

• Energy loss.

• Resistance increase.

• Temperature behaviour.

• Voltage divergence.

• Cell imbalance.

• Evidence of leakage.

• Structural changes.

• Protective-device behaviour.

• Anomalies and trend changes.

The test article may not represent the flight configuration. A cell tested alone may respond differently when constrained, thermally coupled and electrically integrated within a module or battery.

Life tests can be lengthy. Accelerating them without a valid degradation model may produce fast data but poor evidence.

Poor initial planning can result in repeated set-ups, additional hardware, inconclusive tests and unnecessary consumption of limited battery articles.

A technically successful test can still fail to close verification if the requirement, test configuration, pass criterion or evidence trail is unclear.

Missing raw data, sensor locations, calibration details, state-of-charge history or anomaly dispositions can reduce the value of otherwise valid testing.

Battery abuse testing can create fire, venting, explosion, toxic-release and stored-energy hazards. Safety testing requires a specific facility assessment and controlled procedure. The handbook’s description is not a replacement for a test-facility risk assessment.

Why it is wrong: A handbook provides guidance and recommendations. Mandatory obligations arise from applicable standards, contracts and project requirements.

Correct approach: Use it to inform the test strategy and documentation, then map each planned activity to a controlled requirement.

Examples such as temperatures, durations, cycle profiles or electrical conditions should not be copied without establishing mission relevance.

Correct approach: Derive conditions from the mission, hardware limitations, supplier data and approved requirements.

Characterisation explains behaviour. Qualification demonstrates compliance of a representative design against approved qualification requirements.

Correct approach: State the verification purpose of every test before defining the method.

Integration introduces mechanical restraint, thermal gradients, electrical interconnection, protective devices and cell-to-cell interaction.

Correct approach: Define which requirements can be verified at cell, module and battery level.

The handbook includes an applicability matrix covering lot acceptance, acceptance and qualification activities. It should be used as guidance, not as an unexamined universal compliance checklist. 

Battery behaviour depends on activation, storage, state of charge, previous cycling and environmental exposure.

Correct approach: Maintain a controlled history for each test article.

Higher temperature or current can change the degradation mechanism rather than merely speed it up.

Correct approach: Demonstrate the technical basis for acceleration and its relationship to mission conditions.

A facility generates evidence. It does not automatically control the spacecraft’s full requirements baseline or approve flight readiness.

Correct approach: Say that testing was performed against an approved, ECSS-aligned customer specification, where that is factually correct.

UN 38.3 addresses transport-related testing. It does not demonstrate suitability for launch vibration, mission thermal vacuum, radiation exposure, mission cycling or spacecraft integration.

The handbook explicitly excludes battery-management-subsystem testing from its stated scope.

Identify the test article, cell lot, module arrangement, firmware where relevant, interfaces, fixture and instrumentation configuration.

Connect each test objective and pass criterion to an approved requirement.

Document state of charge, temperature, voltage, storage history, previous cycling and relevant conditioning before testing.

Avoid generic profiles where orbit, mission duration, load demand or thermal control materially affect the result.

Retain raw time-history data alongside processed plots and conclusions.

Establish how interruptions, limit exceedances, sensor failures and unexpected responses will be managed.

Use test readiness and post-test reviews to challenge assumptions, configuration, safety controls and evidence quality.

The test report should distinguish measured results, calculated values, engineering interpretation and unverified assumptions.

Defines how requirements will be verified across analysis, inspection, review of design and test.

Defines the test objectives, articles, configurations, sequence, conditions and resources.

Defines technical requirements, test levels, tolerances and success criteria.

Defines the controlled execution steps, measurements, hold points and responses to anomalies.

Records the configuration, execution, results, analysis, deviations and conclusions.

Tracks requirements, methods, evidence and closure status.

Record anomalies, technical assessment, disposition and closure.

Records appropriate storage, maintenance, handling and operational conditions. The handbook places storage and handling information within the user manual.

The agreed requirement has objective, traceable evidence.

Evidence is reviewed, accepted and recorded against the correct requirement.

The test article remains within defined structural, electrical, thermal and safety limits unless the test intentionally investigates failure behaviour.

Capacity, energy, resistance and other controlled parameters remain within approved limits.

The relationship between requirement, test article, configuration, procedure, raw data, analysis and conclusion is clear.

The battery evidence contributes to an overall flight-readiness decision. The handbook alone does not make that decision.

Support the translation of customer and mission requirements into an executable environmental test campaign.

Review test objectives, configurations, instrumentation, sequencing and evidence expectations within the agreed scope.

Develop coordinated mechanical and environmental testing, including relevant vibration, shock and thermal-vacuum activities where the facility capability and safety assessment permit.

Support the preparation or review of:

• Test specifications.

• Test procedures.

• Test set-up records.

• Test reports.

• Data packages.

• Nonconformance evidence.

Provide an independent challenge of test readiness, configuration, traceability and evidence quality.

Generate controlled test evidence for customer review as part of the wider qualification or flight-readiness process.

Resonate should not state that it:

• Certifies a battery as ECSS compliant.

• Grants flight approval.

• Replaces the design authority.

• Determines the full project standard baseline.

• Provides every test listed in the handbook.

The stronger and more credible position is:

Resonate Testing helps customers convert mission and verification requirements into controlled, traceable test evidence.

Your Test Facilitator. Not simply a test facility.

No. It is an ECSS handbook providing supporting guidance. Mandatory obligations depend on the project’s applicable standards, contract and customer requirements.

No. Environmental and operational conditions must be linked to the mission profile and approved project requirements.

It covers electrical characterisation, environmental testing, life testing, safety testing, handling, transport considerations, AIT and associated test documentation.

No. The document explicitly states that battery management subsystem testing is not included in this issue.

Qualification establishes that a representative design can satisfy defined requirements with the prescribed margin. Acceptance testing provides evidence concerning the condition and workmanship of deliverable hardware against acceptance requirements.

The exact project definitions and levels must be obtained from the applicable standards and customer specification.

Sometimes, but only where the requirement, test objective and representativeness justify it. Cell evidence should not automatically be treated as proof of integrated battery behaviour.

No. Transport testing and space qualification have different purposes. The handbook references UN transport requirements but also addresses mission-related environmental, electrical, life and safety concerns.

Mechanical response, electrical performance, heating and safety behaviour can depend upon state of charge. The state of charge should therefore be specified, controlled and recorded.

Yes, the handbook discusses acceleration using factors such as altered timing, higher charge or discharge rates and increased temperature. However, the effect of acceleration on ageing must be assessed to avoid unrealistic over-testing.

The report should identify the test item and conditions, provide test data and analysis, and record related nonconformances and their disposition.

• Qualification Testing Under ECSS

• Acceptance Testing Under ECSS

• Protoflight Testing

• Space Hardware Model Philosophy

• EQM, PFM and FM Explained

• Vibration Testing for Space Hardware

• Shock Testing for Space Hardware

• Thermal Vacuum Testing

• Space Battery Environmental Testing

• Test Fixture Design and Test-Item Representativeness

• Lithium-Ion Battery Capacity and Energy Testing

• Space Battery Life Testing

• Battery Safety and Abuse Testing

• Battery Thermal Vacuum Testing

• Battery Vibration and Shock Testing

• UN 38.3 Versus Space Qualification Testing

• ECSS Verification Planning

• Verification Control Documents

• Requirements Traceability

• Environmental Test Planning

• Space Qualification Evidence

• Test Readiness Reviews

• Test Specifications

• Test Procedures

• Test Reports

• Nonconformance Management

• View the official ECSS-E-HB-20-02A handbook page