{
  "node": {
    "id": "term:functional-safety",
    "type": "Term",
    "label": "Functional safety",
    "properties": {
      "id": "functional-safety",
      "name": "Functional safety",
      "abbr": "ISO 26262",
      "aka": [
        "ASIL"
      ],
      "section": "topic-hvsafety",
      "definition": "The discipline, standardised for vehicles in ISO 26262, of making sure electronic failures do not cause harm. Battery functions such as overvoltage protection are classified by risk into ASIL levels A to D, which set how redundant and verified their hardware and software must be.",
      "related": [
        "bms",
        "high-voltage-interlock",
        "insulation-resistance",
        "fmea",
        "mcu",
        "iso-13849"
      ],
      "url": "https://lemonergy.com/learn/glossary/functional-safety/",
      "mentions": []
    }
  },
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      "target": "topic:topic-hvsafety",
      "type": "belongsTo",
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    {
      "id": "edge:2983",
      "source": "term:functional-safety",
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        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
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    },
    {
      "id": "edge:2984",
      "source": "term:functional-safety",
      "target": "term:high-voltage-interlock",
      "type": "relatedTo",
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        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
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    },
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      "id": "edge:2985",
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      "id": "edge:2988",
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      "target": "reference:iso-functional",
      "type": "cites",
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        "scope": "direct technical reference"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-hvsafety",
      "type": "Topic",
      "label": "High-voltage and functional safety",
      "properties": {
        "id": "topic-hvsafety",
        "name": "High-voltage and functional safety",
        "lede": "Keeping people safe from the pack’s voltage and keeping its electronics safe when they fail: insulation, switching, fusing and the functional-safety process.",
        "context": "Relate protection to faults, detection and response.",
        "example": "Normal-operation current limits do not demonstrate correct contactor behavior under a welded-contact or sensor fault.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/battery-basics/",
        "lesson_label": "Open battery basics"
      }
    },
    {
      "id": "term:bms",
      "type": "Term",
      "label": "Battery management system",
      "properties": {
        "id": "bms",
        "name": "Battery management system",
        "abbr": "BMS",
        "section": "topic-pack",
        "definition": "The electronics and software that keep a battery inside its safe window: measuring every cell voltage and many temperatures, estimating SOC and SOH, balancing cells, computing current limits, controlling the contactors and reporting over the vehicle network.",
        "related": [
          "state-of-charge",
          "cell-balancing",
          "state-of-power",
          "cell-supervision-circuit",
          "contactor",
          "can-bus"
        ],
        "lesson": "fundamentals/battery-basics/#cell-module-pack",
        "url": "https://lemonergy.com/learn/glossary/bms/",
        "mentions": [
          "state-of-health",
          "cell-voltage"
        ]
      }
    },
    {
      "id": "term:high-voltage-interlock",
      "type": "Term",
      "label": "High-voltage interlock loop",
      "properties": {
        "id": "high-voltage-interlock",
        "name": "High-voltage interlock loop",
        "abbr": "HVIL",
        "section": "topic-hvsafety",
        "definition": "A low-voltage signal loop threaded through every high-voltage connector and cover. Opening any of them breaks the loop and the BMS drops the contactors, so a technician cannot reach a live conductor.",
        "related": [
          "contactor",
          "pack-voltage",
          "insulation-resistance",
          "functional-safety"
        ],
        "url": "https://lemonergy.com/learn/glossary/high-voltage-interlock/",
        "mentions": [
          "bms"
        ]
      }
    },
    {
      "id": "term:insulation-resistance",
      "type": "Term",
      "label": "Insulation resistance",
      "properties": {
        "id": "insulation-resistance",
        "name": "Insulation resistance",
        "aka": [
          "isolation resistance",
          "IMD"
        ],
        "section": "topic-hvsafety",
        "definition": "The resistance between the high-voltage circuit and the vehicle chassis, which must stay above about 100 Ω per volt of pack voltage so a person touching the chassis is safe. An insulation monitoring device measures it continuously.",
        "unit": "Ω/V",
        "related": [
          "pack-voltage",
          "high-voltage-interlock",
          "functional-safety",
          "insulation-test"
        ],
        "url": "https://lemonergy.com/learn/glossary/insulation-resistance/",
        "mentions": [
          "volt"
        ]
      }
    },
    {
      "id": "term:fmea",
      "type": "Term",
      "label": "Failure mode and effects analysis",
      "properties": {
        "id": "fmea",
        "name": "Failure mode and effects analysis",
        "abbr": "FMEA",
        "section": "topic-hvsafety",
        "definition": "A structured review that lists every way a component or process could fail, its effect, and how likely it is to happen and be detected, scoring each to prioritise fixes. Battery programmes run it on the cell, the pack design and the production process.",
        "related": [
          "functional-safety",
          "abuse-testing",
          "cell-design",
          "fault-tree-analysis"
        ],
        "url": "https://lemonergy.com/learn/glossary/fmea/",
        "mentions": []
      }
    },
    {
      "id": "term:mcu",
      "type": "Term",
      "label": "Microcontroller",
      "properties": {
        "id": "mcu",
        "name": "Microcontroller",
        "abbr": "MCU",
        "section": "topic-data",
        "definition": "The processor that runs BMS firmware: state estimation, protection, balancing decisions and communication. Automotive BMS controllers use safety microcontrollers with lockstep cores and hardware self-tests so they can meet ASIL C or D.",
        "related": [
          "bmu",
          "firmware",
          "functional-safety",
          "fpga",
          "afe"
        ],
        "url": "https://lemonergy.com/learn/glossary/mcu/",
        "mentions": [
          "bms",
          "lockstep-core"
        ]
      }
    },
    {
      "id": "term:iso-13849",
      "type": "Term",
      "label": "ISO 13849",
      "properties": {
        "id": "iso-13849",
        "name": "ISO 13849",
        "aka": [
          "ISO 13849-1",
          "performance level"
        ],
        "section": "topic-standards-stationary",
        "definition": "The ISO standard for safety-related parts of machine control systems. A risk assessment sets a required performance level from PL a to PL e, met through an architecture category (B, 1 to 4) and a low enough probability of dangerous failure per hour. It applies to cell-production machinery and to battery-powered machines such as automated guided vehicles.",
        "related": [
          "functional-safety",
          "cell-production",
          "gigafactory",
          "fmea",
          "iec-60730"
        ],
        "url": "https://lemonergy.com/learn/glossary/iso-13849/",
        "mentions": []
      }
    },
    {
      "id": "reference:iso-functional",
      "type": "Reference",
      "label": "ISO 26262-1:2018 — Road vehicles — Functional safety — Part 1: Vocabulary",
      "properties": {
        "title": "ISO 26262-1:2018 — Road vehicles — Functional safety — Part 1: Vocabulary",
        "publisher": "International Organization for Standardization",
        "url": "https://www.iso.org/standard/68383.html",
        "type": "Standard catalogue",
        "scope": "Scope and terminology of automotive electrical/electronic functional safety. The catalogue is not the full standard.",
        "year": 2018,
        "accessed": "2026-10-27"
      }
    }
  ]
}