{
  "node": {
    "id": "term:nail-penetration",
    "type": "Term",
    "label": "Nail penetration test",
    "properties": {
      "id": "nail-penetration",
      "name": "Nail penetration test",
      "section": "topic-safety",
      "definition": "Driving a steel nail through a charged cell to create a sudden internal short circuit. It is easy to run and widely cited, but its severity depends on nail size, speed and depth, and it is a poor stand-in for the small latent shorts that cause field failures.",
      "related": [
        "internal-short-circuit",
        "abuse-testing",
        "thermal-runaway"
      ],
      "url": "https://lemonergy.com/learn/glossary/nail-penetration/",
      "mentions": [
        "short-circuit"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:1728",
      "source": "term:nail-penetration",
      "target": "topic:topic-safety",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:1729",
      "source": "term:nail-penetration",
      "target": "term:internal-short-circuit",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1730",
      "source": "term:nail-penetration",
      "target": "term:abuse-testing",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:1731",
      "source": "term:nail-penetration",
      "target": "term:thermal-runaway",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/nail-penetration/short-circuit",
      "source": "term:nail-penetration",
      "target": "term:short-circuit",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    },
    {
      "id": "edge:1733",
      "source": "term:nail-penetration",
      "target": "reference:feng-runaway",
      "type": "cites",
      "properties": {
        "sourceFile": "wiki-references.json",
        "scope": "direct technical reference"
      }
    }
  ],
  "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:internal-short-circuit",
      "type": "Term",
      "label": "Internal short circuit",
      "properties": {
        "id": "internal-short-circuit",
        "name": "Internal short circuit",
        "abbr": "ISC",
        "section": "topic-safety",
        "definition": "An unintended electronic path between the electrodes inside a cell — through a metal particle, a burr, a damaged separator or lithium deposits. It discharges the cell internally and turns its energy into local heat.",
        "related": [
          "thermal-runaway",
          "dendrite",
          "separator",
          "external-short-circuit",
          "self-discharge",
          "internal-short-trigger-device"
        ],
        "lesson": "fundamentals/cell-anatomy/#short-circuit",
        "url": "https://lemonergy.com/learn/glossary/internal-short-circuit/",
        "mentions": [
          "electronic-path",
          "burr",
          "metal-particle-contamination"
        ]
      }
    },
    {
      "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"
        ],
        "url": "https://lemonergy.com/learn/glossary/abuse-testing/",
        "mentions": [
          "overcharge"
        ]
      }
    },
    {
      "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"
        ],
        "lesson": "fundamentals/cell-anatomy/#short-circuit",
        "url": "https://lemonergy.com/learn/glossary/thermal-runaway/",
        "mentions": [
          "overcharge"
        ]
      }
    },
    {
      "id": "term:short-circuit",
      "type": "Term",
      "label": "Short circuit",
      "properties": {
        "id": "short-circuit",
        "name": "Short circuit",
        "section": "topic-units",
        "definition": "A connection of negligible resistance between two points that should be separated, so current is limited only by the source. For a battery it may be external, across the terminals, or internal, between the electrodes inside the cell.",
        "related": [
          "external-short-circuit",
          "internal-short-circuit",
          "fuse",
          "ohms-law"
        ],
        "lesson": "fundamentals/cell-anatomy/#short-circuit",
        "url": "https://lemonergy.com/learn/glossary/short-circuit/",
        "mentions": []
      }
    },
    {
      "id": "reference:feng-runaway",
      "type": "Reference",
      "label": "Thermal runaway mechanism of lithium ion battery for electric vehicles: A review",
      "properties": {
        "title": "Thermal runaway mechanism of lithium ion battery for electric vehicles: A review",
        "publisher": "Energy Storage Materials",
        "url": "https://doi.org/10.1016/j.ensm.2017.05.013",
        "type": "Review article",
        "scope": "Electrical, mechanical and thermal abuse; thermal-runaway mechanisms and propagation.",
        "year": 2018,
        "authors": [
          "Xuning Feng et al."
        ],
        "accessed": "2026-10-27"
      }
    }
  ]
}