{
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    "id": "term:propagation-test",
    "type": "Term",
    "label": "Thermal propagation test",
    "properties": {
      "id": "propagation-test",
      "name": "Thermal propagation test",
      "section": "topic-safety",
      "definition": "Triggering thermal runaway in one cell of a module or pack — by heater, nail or overcharge — and measuring whether and how fast it spreads. Regulations now require at least a warning period, five minutes in several markets, before the cabin is at risk.",
      "related": [
        "thermal-propagation",
        "abuse-testing",
        "thermal-barrier",
        "gtr-20"
      ],
      "url": "https://lemonergy.com/learn/glossary/propagation-test/",
      "mentions": [
        "overcharge",
        "thermal-runaway"
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  "edges": [
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      "id": "edge:1752",
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      "target": "topic:topic-safety",
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      "properties": {
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      }
    },
    {
      "id": "edge:1753",
      "source": "term:propagation-test",
      "target": "term:thermal-propagation",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1754",
      "source": "term:propagation-test",
      "target": "term:abuse-testing",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
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      "id": "edge:1755",
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      "target": "term:thermal-barrier",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
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    },
    {
      "id": "edge:1756",
      "source": "term:propagation-test",
      "target": "term:gtr-20",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
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      "id": "edge:mentions/propagation-test/overcharge",
      "source": "term:propagation-test",
      "target": "term:overcharge",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
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        "field": "definition",
        "meaning": "Text mention; not a causal claim"
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      "id": "edge:mentions/propagation-test/thermal-runaway",
      "source": "term:propagation-test",
      "target": "term:thermal-runaway",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
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        "field": "definition",
        "meaning": "Text mention; not a causal claim"
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      "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"
      }
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      "id": "term:thermal-propagation",
      "type": "Term",
      "label": "Thermal propagation",
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        "id": "thermal-propagation",
        "name": "Thermal propagation",
        "section": "topic-safety",
        "definition": "Thermal runaway spreading from one cell to its neighbours through conducted heat, hot gas and flame. Pack designs are judged by whether, and how slowly, a single failing cell takes the rest with it.",
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          "thermal-barrier",
          "venting",
          "module",
          "propagation-test"
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        "mentions": []
      }
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    {
      "id": "term:abuse-testing",
      "type": "Term",
      "label": "Abuse testing",
      "properties": {
        "id": "abuse-testing",
        "name": "Abuse testing",
        "section": "topic-safety",
        "definition": "Deliberately driving cells and packs beyond their limits — overcharge, crush, nail penetration, external short, heating, drop — to see how they fail. Standards define each test and rank the outcome on a hazard scale from no effect to explosion.",
        "related": [
          "nail-penetration",
          "overcharge-test",
          "crush-test",
          "short-circuit-test",
          "hazard-level",
          "oven-test"
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        "url": "https://lemonergy.com/learn/glossary/abuse-testing/",
        "mentions": [
          "overcharge"
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      "id": "term:thermal-barrier",
      "type": "Term",
      "label": "Thermal barrier",
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        "id": "thermal-barrier",
        "name": "Thermal barrier",
        "aka": [
          "fire-resistant pad",
          "mica sheet"
        ],
        "section": "topic-safety",
        "definition": "An insulating sheet — aerogel, mica, ceramic fibre or intumescent material — placed between cells or modules to slow heat transfer during a thermal event and buy time for occupants to leave.",
        "related": [
          "thermal-propagation",
          "compression-pad",
          "module"
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        "url": "https://lemonergy.com/learn/glossary/thermal-barrier/",
        "mentions": [
          "aerogel",
          "intumescent-material"
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      "id": "term:gtr-20",
      "type": "Term",
      "label": "GTR 20",
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        "id": "gtr-20",
        "name": "GTR 20",
        "aka": [
          "UN GTR No. 20",
          "EVS-GTR"
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        "section": "topic-standards-vehicle",
        "definition": "The UN Global Technical Regulation on electric vehicle safety, the basis of national rules in Europe, China, Japan and elsewhere. Its thermal propagation clause requires a warning to occupants at least five minutes before a hazardous condition in the cabin.",
        "related": [
          "propagation-test",
          "thermal-propagation",
          "iec-62660",
          "un-r100-03"
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        "url": "https://lemonergy.com/learn/glossary/gtr-20/",
        "mentions": [
          "electric-vehicle"
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      "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"
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        "mentions": [
          "electrode",
          "positive-electrode",
          "electrolyte"
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    {
      "id": "term:thermal-runaway",
      "type": "Term",
      "label": "Thermal runaway",
      "properties": {
        "id": "thermal-runaway",
        "name": "Thermal runaway",
        "section": "topic-safety",
        "definition": "Self-accelerating heating in a cell: heat speeds up reactions that release more heat, until the cell vents, catches fire or ruptures. An internal short, overcharge or external heating can trigger it.",
        "related": [
          "onset-temperature",
          "thermal-propagation",
          "venting",
          "separator-shutdown",
          "thermal-runaway-energy",
          "exothermic"
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        "lesson": "fundamentals/cell-anatomy/#short-circuit",
        "url": "https://lemonergy.com/learn/glossary/thermal-runaway/",
        "mentions": [
          "overcharge"
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}