{
  "node": {
    "id": "term:protection-circuit",
    "type": "Term",
    "label": "Protection circuit module",
    "properties": {
      "id": "protection-circuit",
      "name": "Protection circuit module",
      "abbr": "PCM",
      "aka": [
        "protection board",
        "PCB"
      ],
      "section": "topic-pack",
      "definition": "The small circuit on a consumer cell or pack that disconnects it on overvoltage, undervoltage, overcurrent or overtemperature, using MOSFETs as switches. It is the minimum BMS; it protects but does not estimate state or balance.",
      "related": [
        "bms",
        "overcharge",
        "over-discharge",
        "fuel-gauge"
      ],
      "url": "https://lemonergy.com/learn/glossary/protection-circuit/",
      "mentions": []
    }
  },
  "edges": [
    {
      "id": "edge:3048",
      "source": "term:protection-circuit",
      "target": "topic:topic-pack",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:3049",
      "source": "term:protection-circuit",
      "target": "term:bms",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3050",
      "source": "term:protection-circuit",
      "target": "term:overcharge",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3051",
      "source": "term:protection-circuit",
      "target": "term:over-discharge",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3052",
      "source": "term:protection-circuit",
      "target": "term:fuel-gauge",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3053",
      "source": "term:protection-circuit",
      "target": "reference:ti-bms",
      "type": "cites",
      "properties": {
        "sourceFile": "wiki-references.json",
        "scope": "direct technical reference"
      }
    }
  ],
  "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: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:overcharge",
      "type": "Term",
      "label": "Overcharge",
      "properties": {
        "id": "overcharge",
        "name": "Overcharge",
        "section": "topic-charging",
        "definition": "Charging past the upper cutoff voltage. The positive electrode over-delithiates and releases oxygen, the electrolyte oxidises and lithium plates on the negative, so an unprotected overcharge can end in thermal runaway.",
        "related": [
          "cutoff-voltage",
          "thermal-runaway",
          "bms",
          "overcharge-test",
          "electrolyte-decomposition"
        ],
        "url": "https://lemonergy.com/learn/glossary/overcharge/",
        "mentions": [
          "electrode",
          "positive-electrode",
          "electrolyte"
        ]
      }
    },
    {
      "id": "term:over-discharge",
      "type": "Term",
      "label": "Over-discharge",
      "properties": {
        "id": "over-discharge",
        "name": "Over-discharge",
        "aka": [
          "deep discharge"
        ],
        "section": "topic-charging",
        "definition": "Discharging below the lower cutoff voltage. Near 1.5 V the copper current collector begins to dissolve, and on the next charge it can redeposit as metal that shorts the cell, so a deeply discharged cell should not simply be recharged.",
        "related": [
          "cutoff-voltage",
          "copper-dissolution",
          "internal-short-circuit",
          "bms",
          "low-voltage-disconnect"
        ],
        "url": "https://lemonergy.com/learn/glossary/over-discharge/",
        "mentions": [
          "current-collector"
        ]
      }
    },
    {
      "id": "term:fuel-gauge",
      "type": "Term",
      "label": "Fuel gauge",
      "properties": {
        "id": "fuel-gauge",
        "name": "Fuel gauge",
        "aka": [
          "gas gauge"
        ],
        "section": "topic-pack",
        "definition": "The single chip in a phone, laptop or power tool that does the BMS’s state-estimation job for one or a few cells: coulomb counting corrected by an OCV model, with impedance tracking in better parts. It reports remaining capacity over SMBus or I²C.",
        "related": [
          "coulomb-counting",
          "state-of-charge",
          "smbus",
          "consumer-electronics",
          "afe"
        ],
        "url": "https://lemonergy.com/learn/glossary/fuel-gauge/",
        "mentions": [
          "coulomb",
          "impedance",
          "open-circuit-voltage",
          "bms"
        ]
      }
    },
    {
      "id": "reference:ti-bms",
      "type": "Reference",
      "label": "Getting Started with the BQ76925",
      "properties": {
        "title": "Getting Started with the BQ76925",
        "publisher": "Texas Instruments",
        "url": "https://www.ti.com/lit/an/slua619b/slua619b.pdf",
        "type": "Application report",
        "scope": "A concrete BMS analog front-end example: cell voltage, current, temperature measurement and MCU integration.",
        "year": 2019,
        "accessed": "2026-10-27"
      }
    }
  ]
}