{
  "node": {
    "id": "term:24v-system",
    "type": "Term",
    "label": "24 V system",
    "properties": {
      "id": "24v-system",
      "name": "24 V system",
      "aka": [
        "24 V electrical system",
        "24-volt system"
      ],
      "section": "topic-applications",
      "definition": "The low-voltage electrical system of trucks, buses and coaches, traditionally fed by two 12 V lead–acid batteries in series. In an electric bus or truck it still powers the controllers, doors and lights, kept charged by a DC/DC converter from the traction pack; its higher voltage than a car’s 12 V halves the current for the same load.",
      "related": [
        "auxiliary-battery",
        "dc-dc-converter",
        "electric-bus",
        "48v-system",
        "extra-low-voltage",
        "lead-acid"
      ],
      "url": "https://lemonergy.com/learn/glossary/24v-system/",
      "mentions": []
    }
  },
  "edges": [
    {
      "id": "edge:6894",
      "source": "term:24v-system",
      "target": "topic:topic-applications",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:6895",
      "source": "term:24v-system",
      "target": "term:auxiliary-battery",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6896",
      "source": "term:24v-system",
      "target": "term:dc-dc-converter",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6897",
      "source": "term:24v-system",
      "target": "term:electric-bus",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6898",
      "source": "term:24v-system",
      "target": "term:48v-system",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6899",
      "source": "term:24v-system",
      "target": "term:extra-low-voltage",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:6900",
      "source": "term:24v-system",
      "target": "term:lead-acid",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-applications",
      "type": "Topic",
      "label": "Applications and market",
      "properties": {
        "id": "topic-applications",
        "name": "Applications and market",
        "lede": "Where batteries are used, and the terms used to buy, size and compare them.",
        "context": "Start with mission energy, peak power and operating conditions.",
        "example": "20 kWh total energy and a ten-second 100 kW peak constrain different design aspects.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/capacity-and-c-rate/",
        "lesson_label": "Open energy and power"
      }
    },
    {
      "id": "term:auxiliary-battery",
      "type": "Term",
      "label": "Auxiliary battery",
      "properties": {
        "id": "auxiliary-battery",
        "name": "Auxiliary battery",
        "aka": [
          "12 V battery",
          "low-voltage battery"
        ],
        "section": "topic-pack",
        "definition": "The small 12 V or 48 V battery in an electric vehicle that powers the controllers, lights and locks and wakes the BMS, kept charged from the high-voltage pack through a DC/DC converter. A flat auxiliary battery immobilises the car however full the main pack is.",
        "related": [
          "dc-dc-converter",
          "lead-acid",
          "pack",
          "lin-bus"
        ],
        "url": "https://lemonergy.com/learn/glossary/auxiliary-battery/",
        "mentions": [
          "bms",
          "electric-vehicle"
        ]
      }
    },
    {
      "id": "term:dc-dc-converter",
      "type": "Term",
      "label": "DC/DC converter",
      "properties": {
        "id": "dc-dc-converter",
        "name": "DC/DC converter",
        "section": "topic-pack",
        "definition": "The power electronics that step the high-voltage pack down to 12 V or 48 V for the auxiliary systems, replacing the alternator of a combustion car. Boost converters also appear between an 800 V pack and a 400 V charger.",
        "related": [
          "auxiliary-battery",
          "inverter",
          "pack-voltage"
        ],
        "url": "https://lemonergy.com/learn/glossary/dc-dc-converter/",
        "mentions": [
          "charger"
        ]
      }
    },
    {
      "id": "term:electric-bus",
      "type": "Term",
      "label": "Electric bus",
      "properties": {
        "id": "electric-bus",
        "name": "Electric bus",
        "abbr": "e-bus",
        "section": "topic-applications",
        "definition": "A battery-electric city or coach bus, with packs of 300–700 kWh on the roof and at the rear, LFP or NMC, charged overnight in the depot or at the terminus by pantograph. Its duty cycle — long hours, deep daily cycles, a twelve-year life — makes battery aging the central engineering question.",
        "related": [
          "depot-charging",
          "pantograph-charging",
          "vdv",
          "sort-cycle",
          "total-cost-of-ownership",
          "opportunity-charging"
        ],
        "url": "https://lemonergy.com/learn/glossary/electric-bus/",
        "mentions": [
          "kilowatt-hour"
        ]
      }
    },
    {
      "id": "term:48v-system",
      "type": "Term",
      "label": "48 V system",
      "properties": {
        "id": "48v-system",
        "name": "48 V system",
        "aka": [
          "mild hybrid"
        ],
        "section": "topic-applications",
        "definition": "A vehicle electrical architecture at 48 V, used for mild hybrids and heavy accessories. It stays below the 60 V threshold at which high-voltage safety rules begin, so it needs no orange cables or interlocks.",
        "related": [
          "hybrid-vehicle",
          "auxiliary-battery",
          "pack-voltage",
          "24v-system"
        ],
        "url": "https://lemonergy.com/learn/glossary/48v-system/",
        "mentions": []
      }
    },
    {
      "id": "term:extra-low-voltage",
      "type": "Term",
      "label": "Extra-low voltage",
      "properties": {
        "id": "extra-low-voltage",
        "name": "Extra-low voltage",
        "abbr": "ELV",
        "aka": [
          "SELV",
          "PELV",
          "FELV",
          "safety extra-low voltage",
          "protective extra-low voltage"
        ],
        "section": "topic-hvsafety",
        "definition": "Voltage low enough to need reduced shock protection: at most 50 V AC rms or 120 V ripple-free DC under IEC 61140. SELV is separated from higher voltages and from earth; PELV is separated but earthed; FELV is low in value only, without protective separation, so it is protected like the circuit feeding it. Vehicle rules draw their line lower, at 60 V DC.",
        "related": [
          "voltage-class",
          "insulation-resistance",
          "equipotential-bonding",
          "48v-system"
        ],
        "url": "https://lemonergy.com/learn/glossary/extra-low-voltage/",
        "mentions": []
      }
    },
    {
      "id": "term:lead-acid",
      "type": "Term",
      "label": "Lead–acid battery",
      "properties": {
        "id": "lead-acid",
        "name": "Lead–acid battery",
        "section": "topic-other-chemistries",
        "definition": "The oldest rechargeable chemistry, lead and lead dioxide electrodes in sulfuric acid, at 2 V per cell. Heavy and short-lived in deep cycling but cheap, recyclable and good at cold cranking, it still starts most cars and backs up most telecom sites.",
        "related": [
          "nominal-voltage",
          "recycling",
          "specific-energy"
        ],
        "lesson": "labs/battery-materials-lab/#bml-market",
        "url": "https://lemonergy.com/learn/glossary/lead-acid/",
        "mentions": []
      }
    }
  ]
}