{
  "node": {
    "id": "term:bcu",
    "type": "Term",
    "label": "Battery control unit",
    "properties": {
      "id": "bcu",
      "name": "Battery control unit",
      "abbr": "BCU",
      "aka": [
        "battery junction controller"
      ],
      "section": "topic-data",
      "definition": "In layered battery systems, the controller between the module-level BMUs and the vehicle or site controller: it aggregates several strings or racks, decides which may connect, and presents one battery to the outside. Stationary storage usually calls the levels cell, module, rack and system.",
      "related": [
        "bmu",
        "bms",
        "battery-disconnect-unit",
        "stationary-storage",
        "energy-management-system"
      ],
      "url": "https://lemonergy.com/learn/glossary/bcu/",
      "mentions": [
        "power-plant-controller"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:3998",
      "source": "term:bcu",
      "target": "topic:topic-data",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:3999",
      "source": "term:bcu",
      "target": "term:bmu",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4000",
      "source": "term:bcu",
      "target": "term:bms",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4001",
      "source": "term:bcu",
      "target": "term:battery-disconnect-unit",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4002",
      "source": "term:bcu",
      "target": "term:stationary-storage",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4003",
      "source": "term:bcu",
      "target": "term:energy-management-system",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/bcu/power-plant-controller",
      "source": "term:bcu",
      "target": "term:power-plant-controller",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-data",
      "type": "Topic",
      "label": "Data, communication and electronics",
      "properties": {
        "id": "topic-data",
        "name": "Data, communication and electronics",
        "lede": "The control units, chips, protocols and file formats through which a battery is measured, controlled and logged.",
        "context": "Separate quantities from encoding and transport.",
        "example": "2500 in a log might mean 25.00 °C, 2.5 V or raw counts. Units and scale must accompany the value.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/battery-basics/",
        "lesson_label": "Open battery basics"
      }
    },
    {
      "id": "term:bmu",
      "type": "Term",
      "label": "Battery management unit",
      "properties": {
        "id": "bmu",
        "name": "Battery management unit",
        "abbr": "BMU",
        "aka": [
          "BMS master",
          "master BMS"
        ],
        "section": "topic-data",
        "definition": "The master controller of a battery management system: it collects cell voltages and temperatures from the monitoring boards, runs the state estimation and protection logic, drives the contactors and talks to the vehicle. In some architectures the same name is used for a per-module slave, so a datasheet’s block diagram is the safe reference.",
        "related": [
          "bms",
          "cell-supervision-circuit",
          "bcu",
          "contactor",
          "can-bus",
          "bms-power-modes"
        ],
        "url": "https://lemonergy.com/learn/glossary/bmu/",
        "mentions": [
          "datasheet"
        ]
      }
    },
    {
      "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:battery-disconnect-unit",
      "type": "Term",
      "label": "Battery disconnect unit",
      "properties": {
        "id": "battery-disconnect-unit",
        "name": "Battery disconnect unit",
        "abbr": "BDU",
        "aka": [
          "battery junction box"
        ],
        "section": "topic-hvsafety",
        "definition": "The box inside the pack that holds the contactors, pre-charge circuit, main fuse or pyrofuse and current sensor, where the pack’s high-voltage connections are made and broken.",
        "related": [
          "contactor",
          "pre-charge",
          "fuse",
          "pyrofuse",
          "current-sensor"
        ],
        "url": "https://lemonergy.com/learn/glossary/battery-disconnect-unit/",
        "mentions": []
      }
    },
    {
      "id": "term:stationary-storage",
      "type": "Term",
      "label": "Stationary storage",
      "properties": {
        "id": "stationary-storage",
        "name": "Stationary storage",
        "abbr": "BESS",
        "aka": [
          "battery energy storage system",
          "ESS"
        ],
        "section": "topic-applications",
        "definition": "Batteries installed in a fixed place — a container at a solar farm, a cabinet in a home — to shift energy in time or support the grid. LFP cells dominate because cost per cycle and safety matter more than mass.",
        "related": [
          "lfp",
          "energy-management-system",
          "inverter",
          "energy-arbitrage",
          "long-duration-storage",
          "ul-9540a"
        ],
        "url": "https://lemonergy.com/learn/glossary/stationary-storage/",
        "mentions": []
      }
    },
    {
      "id": "term:energy-management-system",
      "type": "Term",
      "label": "Energy management system",
      "properties": {
        "id": "energy-management-system",
        "name": "Energy management system",
        "abbr": "EMS",
        "section": "topic-pack",
        "definition": "The site-level controller of a storage system that decides when to charge and discharge according to prices, grid signals and the battery’s limits, and dispatches those commands to the BMS and inverters.",
        "related": [
          "bms",
          "inverter",
          "stationary-storage",
          "modbus",
          "energy-arbitrage"
        ],
        "url": "https://lemonergy.com/learn/glossary/energy-management-system/",
        "mentions": []
      }
    },
    {
      "id": "term:power-plant-controller",
      "type": "Term",
      "label": "Power plant controller",
      "properties": {
        "id": "power-plant-controller",
        "name": "Power plant controller",
        "abbr": "PPC",
        "aka": [
          "battery plant controller",
          "plant controller",
          "site controller"
        ],
        "section": "topic-data",
        "definition": "The fast closed-loop controller of a grid-connected battery plant that regulates active and reactive power, voltage and frequency response at the point of connection, dispatching setpoints to the inverters. It enforces the grid code, while the energy management system above it decides the schedule.",
        "related": [
          "energy-management-system",
          "inverter",
          "stationary-storage",
          "frequency-regulation",
          "string"
        ],
        "url": "https://lemonergy.com/learn/glossary/power-plant-controller/",
        "mentions": [
          "reactive-power-support"
        ]
      }
    }
  ]
}