ISO/TR 20891:2020 PDF

Overview

ISO/TR 20891:2020 - "Space systems - Space batteries - Guidelines for in‑flight health assessment of lithium‑ion batteries" provides structured guidance on how to assess the health (SoH) of lithium‑ion space batteries during flight. The technical report describes current methods, limitations arising from spacecraft telemetry and operations, and practical recommendations for battery suppliers, spacecraft manufacturers and operators to make in‑flight battery monitoring more reliable and actionable.

Key Topics

• State of Health (SoH) concepts and definitions, including the operational meaning of a “healthy” battery versus predicted degradation.
• Battery capacity assessment methods (direct and indirect) and limitations for in‑flight measurement.
• Internal resistance and impedance: measurement approaches including electrochemical impedance spectroscopy (EIS), spectral impedance techniques, and relationships between resistance and capacity.
• Global model fitting: using numerical battery models fit to in‑flight telemetry to extract ageing parameters.
• Spacecraft telemetry specificities: effects of ADC resolution, sampling frequency, synchronization of voltage/current/temperature, on‑board memory constraints and signal digitization on health assessment.
• Practical constraints: how operational load profiles, temperature variation, orbit dynamics and data quality affect in‑flight SoH evaluation.
• Recommendations for easing in‑flight health assessment: pre‑flight battery characterization, telemetry requirements, data formatting and on‑board/ground data processing practices.

Practical Applications

• Mission operations and flight controllers can use the guidelines to establish alarm thresholds, perform routine monitoring and detect anomalies early to protect spacecraft passivation and de‑orbiting procedures.
• Spacecraft manufacturers and system engineers can design telemetry and power architectures to enable robust in‑flight SoH estimation (e.g., ensure synchronized current/voltage sampling and adequate resolution).
• Battery suppliers and test laboratories can adopt the recommended pre‑flight characterization and provide baseline models or parameters to simplify in‑flight model fitting and trend analysis.
• Program managers and mission planners use SoH assessments to support decisions on mission extension, contingency planning and end‑of‑life estimates.

Related Standards

• ISO 17546 - Space systems - Lithium ion battery for space vehicles - Design and verification requirements (normative reference cited by ISO/TR 20891:2020).

ISO/TR 20891:2020 is a practical resource for anyone responsible for the design, verification, telemetry design or operational monitoring of lithium‑ion batteries in space missions, offering methods and recommendations to improve in‑flight battery health assessment and extend mission assurance.