Functional Safety

Battery functional safety is all about reducing the risks around the electrical and control aspects of a battery design. The process needs to work through the following steps:

  1. Functional Safety Fundamentals & Standards — ISO 26262 vs IEC 61508/60730, and Safety of the Intended Function (SOTIF, ISO 21448).
  2. BMS Hazard Analysis & Risk Assessment (HARA) — the BMS hazard catalogue, Severity/Exposure/Controllability scoring, and how it maps to an ASIL rating.
  3. BMS Safety Goals & Concept (FSC/TSC) — safety goal derivation, Fault Handling Time Intervals, ASIL decomposition, and safe-state strategy.
  4. BMS Hardware Safety Mechanisms — contactor drive and AFE safety architecture, current and isolation monitoring (see also the SPFM/LFM/PMHF architectural metrics page).
  5. BMS Software Safety (ISO 26262 Part 6) — Freedom From Interference and MPU partitioning, MISRA C, and watchdog/CRC mechanisms.
  6. Safety Case & Verification — fault injection testing, Hardware-in-the-Loop validation, and assembling the safety case itself.
  7. Cross-Industry Functional Safety Comparison — ISO 26262 vs IEC 61508/62619 vs ISO 13849 vs DO-178C, and whether an ASIL D BMS can drop into a BESS pack.

Software Development and Functional Safety

By effectively integrating Automotive SPICE® or CMMI with functional safety standards like ISO 26262 or IEC 61508, organizations can significantly enhance the safety and reliability of their products. A well-structured process framework, coupled with rigorous safety engineering practices, is essential for developing and maintaining safety-critical systems.

Legislation, Rules and Regulations

  • IEC 61508 — The base functional-safety standard for electrical and electronic control systems, defining the Safety Integrity Level (SIL) framework that safety-critical BMS functions like contactor control and isolation monitoring are typically assessed against.
  • ISO 26262 — The automotive-specific functional safety standard, translating IEC 61508’s approach into ASIL classifications (A–D) for vehicle E/E systems, including the BMS.
  • ISO/SAE 21434 — Defines the cybersecurity engineering process for road-vehicle E/E systems across their full lifecycle, including the Threat Analysis and Risk Assessment (TARA) methodology used to manage cyber risk in systems like the BMS.
  • BMS Cybersecurity — Applies the TARA process and AUTOSAR SecOC message authentication specifically to BMS attack surfaces (contactor control, balancing commands), and covers why safety and security cases are run together.

See also: Safety Concept