{
  "node": {
    "id": "term:ptc",
    "type": "Term",
    "label": "Positive temperature coefficient device",
    "properties": {
      "id": "ptc",
      "name": "Positive temperature coefficient device",
      "abbr": "PTC",
      "section": "topic-safety",
      "definition": "A polymer element in series with a cell whose resistance jumps when it heats, choking an external short-circuit current. It resets as it cools, unlike a fuse, but adds resistance and does not help against internal faults.",
      "related": [
        "external-short-circuit",
        "fuse",
        "current-interrupt-device"
      ],
      "url": "https://lemonergy.com/learn/glossary/ptc/",
      "mentions": []
    }
  },
  "edges": [
    {
      "id": "edge:1691",
      "source": "term:ptc",
      "target": "topic:topic-safety",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:1692",
      "source": "term:ptc",
      "target": "term:external-short-circuit",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1693",
      "source": "term:ptc",
      "target": "term:fuse",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1694",
      "source": "term:ptc",
      "target": "term:current-interrupt-device",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-safety",
      "type": "Topic",
      "label": "Safety and abuse",
      "properties": {
        "id": "topic-safety",
        "name": "Safety and abuse",
        "lede": "How cells fail dangerously, how that is tested, and what is built in to stop it.",
        "context": "Connect mechanisms with appropriate test evidence.",
        "example": "A low normal-load temperature does not demonstrate thermal-runaway containment.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/battery-aging/",
        "lesson_label": "Open degradation mechanisms"
      }
    },
    {
      "id": "term:external-short-circuit",
      "type": "Term",
      "label": "External short circuit",
      "properties": {
        "id": "external-short-circuit",
        "name": "External short circuit",
        "section": "topic-safety",
        "definition": "A low-resistance connection between the terminals outside the cell, driving currents of hundreds of amperes. Fuses, the current interrupt device and a positive-temperature-coefficient element are the layers of protection against it.",
        "related": [
          "internal-short-circuit",
          "fuse",
          "current-interrupt-device",
          "ptc",
          "short-circuit-test"
        ],
        "url": "https://lemonergy.com/learn/glossary/external-short-circuit/",
        "mentions": []
      }
    },
    {
      "id": "term:fuse",
      "type": "Term",
      "label": "Fuse",
      "properties": {
        "id": "fuse",
        "name": "Fuse",
        "section": "topic-hvsafety",
        "definition": "A link that melts and opens the circuit when current exceeds its rating. Packs use a main fuse in the high-voltage path and often a small fuse on each parallel cell connection, so one shorted cell does not drain its neighbours into the fault.",
        "related": [
          "external-short-circuit",
          "pyrofuse",
          "battery-disconnect-unit",
          "series-parallel",
          "cell-level-fuse"
        ],
        "url": "https://lemonergy.com/learn/glossary/fuse/",
        "mentions": []
      }
    },
    {
      "id": "term:current-interrupt-device",
      "type": "Term",
      "label": "Current interrupt device",
      "properties": {
        "id": "current-interrupt-device",
        "name": "Current interrupt device",
        "abbr": "CID",
        "section": "topic-safety",
        "definition": "A pressure-activated switch in the cap of a cylindrical cell. When internal pressure rises, usually from overcharge, a disc flips and permanently breaks the current path, removing the cell from the circuit before it vents.",
        "related": [
          "vent",
          "overcharge",
          "ptc",
          "cylindrical-cell"
        ],
        "url": "https://lemonergy.com/learn/glossary/current-interrupt-device/",
        "mentions": []
      }
    }
  ]
}