{
  "node": {
    "id": "term:redundant-bms",
    "type": "Term",
    "label": "Redundant BMS architecture",
    "properties": {
      "id": "redundant-bms",
      "name": "Redundant BMS architecture",
      "aka": [
        "redundant BMS",
        "secondary safety monitor"
      ],
      "section": "topic-pack",
      "definition": "A BMS design that duplicates safety-critical functions so no single failure can hide a hazard: an independent second voltage monitor beside the main measurement chip, two current sensors of different principle, a watchdog or second processor, and two separate paths to open the contactors. It is how BMS hardware reaches ASIL C or D.",
      "related": [
        "functional-safety",
        "bms-architecture",
        "hardware-safety-metrics",
        "lockstep-core",
        "current-sensor",
        "diagnostic-coverage"
      ],
      "url": "https://lemonergy.com/learn/glossary/redundant-bms/",
      "mentions": [
        "bms"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:4995",
      "source": "term:redundant-bms",
      "target": "topic:topic-pack",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:4996",
      "source": "term:redundant-bms",
      "target": "term:functional-safety",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4997",
      "source": "term:redundant-bms",
      "target": "term:bms-architecture",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4998",
      "source": "term:redundant-bms",
      "target": "term:hardware-safety-metrics",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4999",
      "source": "term:redundant-bms",
      "target": "term:lockstep-core",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5000",
      "source": "term:redundant-bms",
      "target": "term:current-sensor",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5001",
      "source": "term:redundant-bms",
      "target": "term:diagnostic-coverage",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/redundant-bms/bms",
      "source": "term:redundant-bms",
      "target": "term:bms",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-pack",
      "type": "Topic",
      "label": "Modules, packs and battery management",
      "properties": {
        "id": "topic-pack",
        "name": "Modules, packs and battery management",
        "lede": "From a single cell to a working battery system, and the electronics that keep it safe.",
        "context": "Make series/parallel architecture explicit.",
        "example": "Twelve 3.6 V, 5 Ah cells in 6s2p give 21.6 V, 10 Ah and 216 Wh nominally before other restrictions.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/cell-architecture/",
        "lesson_label": "Open cell architecture"
      }
    },
    {
      "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": []
      }
    },
    {
      "id": "term:bms-architecture",
      "type": "Term",
      "label": "BMS architecture",
      "properties": {
        "id": "bms-architecture",
        "name": "BMS architecture",
        "aka": [
          "centralised BMS",
          "centralized BMS",
          "distributed BMS",
          "modular BMS",
          "master–slave BMS",
          "rack BMS"
        ],
        "section": "topic-pack",
        "definition": "How a BMS’s electronics are divided across the pack. A centralised BMS wires every cell to one board, suiting small packs; a modular or master–slave design puts a monitoring board on each module reporting to one controller; a distributed design puts electronics on each cell. Stationary systems add tiers: module, rack and system-level BMS.",
        "related": [
          "bms",
          "cell-supervision-circuit",
          "bmu",
          "wireless-bms",
          "string",
          "redundant-bms"
        ],
        "url": "https://lemonergy.com/learn/glossary/bms-architecture/",
        "mentions": []
      }
    },
    {
      "id": "term:hardware-safety-metrics",
      "type": "Term",
      "label": "Hardware safety metrics",
      "properties": {
        "id": "hardware-safety-metrics",
        "name": "Hardware safety metrics",
        "abbr": "SPFM, LFM, PMHF",
        "aka": [
          "single-point fault metric",
          "latent fault metric",
          "probabilistic metric for random hardware failures",
          "hardware architectural metrics"
        ],
        "section": "topic-hvsafety",
        "definition": "The ISO 26262 numbers showing that random hardware failures are under control. The single-point and latent fault metrics are the shares of failures that safety mechanisms cover — at least 99% and 90% for ASIL D — and PMHF is the residual rate of violating a safety goal, below 10⁻⁸ per hour (10 FIT) for ASIL D.",
        "related": [
          "functional-safety",
          "diagnostic-coverage",
          "safety-concept",
          "fmea",
          "redundant-bms"
        ],
        "url": "https://lemonergy.com/learn/glossary/hardware-safety-metrics/",
        "mentions": []
      }
    },
    {
      "id": "term:lockstep-core",
      "type": "Term",
      "label": "Lockstep core",
      "properties": {
        "id": "lockstep-core",
        "name": "Lockstep core",
        "aka": [
          "dual-core lockstep",
          "DCLS",
          "lockstep processor",
          "lockstep"
        ],
        "section": "topic-data",
        "definition": "Two identical processor cores running the same program slightly offset in time, with hardware comparing their outputs continuously. Any mismatch, from a radiation-flipped bit or a silicon fault, triggers a reset or safe state, giving the high diagnostic coverage a BMS controller needs for ASIL C or D.",
        "related": [
          "mcu",
          "functional-safety",
          "diagnostic-coverage",
          "redundant-bms",
          "hardware-safety-metrics"
        ],
        "url": "https://lemonergy.com/learn/glossary/lockstep-core/",
        "mentions": [
          "bms"
        ]
      }
    },
    {
      "id": "term:current-sensor",
      "type": "Term",
      "label": "Current sensor",
      "properties": {
        "id": "current-sensor",
        "name": "Current sensor",
        "aka": [
          "shunt",
          "Hall sensor"
        ],
        "section": "topic-pack",
        "definition": "The device that measures pack current for coulomb counting and protection: a precision shunt resistor read by an amplifier, or a Hall-effect sensor around the cable. Offset error in this sensor is what makes SOC drift between OCV corrections.",
        "related": [
          "coulomb-counting",
          "bms",
          "battery-disconnect-unit",
          "state-of-charge"
        ],
        "url": "https://lemonergy.com/learn/glossary/current-sensor/",
        "mentions": [
          "coulomb",
          "open-circuit-voltage"
        ]
      }
    },
    {
      "id": "term:diagnostic-coverage",
      "type": "Term",
      "label": "Diagnostic coverage",
      "properties": {
        "id": "diagnostic-coverage",
        "name": "Diagnostic coverage",
        "section": "topic-hvsafety",
        "definition": "The fraction of a component’s failure rate that a safety mechanism detects or controls. ISO 26262 treats coverage from about 60% as low, from 90% as medium and from 99% as high; comparing two independent measurements of the same cell voltage typically earns high coverage, while a simple plausibility check earns much less.",
        "formula": "coverage = λ_detected / λ_total",
        "related": [
          "hardware-safety-metrics",
          "functional-safety",
          "redundant-bms",
          "fmea",
          "dtc"
        ],
        "example": {
          "title": "Calculate a simplified coverage fraction",
          "text": "If relevant dangerous failure rates total 100 units and 90 of those units are detected by the stated diagnostics, this simplified coverage is 90%. Counting failure modes without weighting their rates gives a different quantity."
        },
        "url": "https://lemonergy.com/learn/glossary/diagnostic-coverage/",
        "mentions": [
          "cell-voltage"
        ]
      }
    },
    {
      "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"
        ]
      }
    }
  ]
}