{
  "node": {
    "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"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:3990",
      "source": "term:bmu",
      "target": "topic:topic-data",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:3991",
      "source": "term:bmu",
      "target": "term:bms",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3992",
      "source": "term:bmu",
      "target": "term:cell-supervision-circuit",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3993",
      "source": "term:bmu",
      "target": "term:bcu",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3994",
      "source": "term:bmu",
      "target": "term:contactor",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3995",
      "source": "term:bmu",
      "target": "term:can-bus",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3996",
      "source": "term:bmu",
      "target": "term:bms-power-modes",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/bmu/datasheet",
      "source": "term:bmu",
      "target": "term:datasheet",
      "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: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:cell-supervision-circuit",
      "type": "Term",
      "label": "Cell supervision circuit",
      "properties": {
        "id": "cell-supervision-circuit",
        "name": "Cell supervision circuit",
        "abbr": "CSC",
        "aka": [
          "cell monitoring unit",
          "CMU",
          "slave BMS"
        ],
        "section": "topic-pack",
        "definition": "The board on each module that measures its cell voltages and temperatures and switches its balancing resistors, reporting to the central BMS controller. It is usually built around a dedicated monitoring chip and linked by isoSPI or CAN.",
        "related": [
          "bms",
          "cell-balancing",
          "isospi",
          "voltage-sense",
          "afe",
          "wireless-bms"
        ],
        "url": "https://lemonergy.com/learn/glossary/cell-supervision-circuit/",
        "mentions": []
      }
    },
    {
      "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"
        ]
      }
    },
    {
      "id": "term:contactor",
      "type": "Term",
      "label": "Contactor",
      "properties": {
        "id": "contactor",
        "name": "Contactor",
        "section": "topic-hvsafety",
        "definition": "A heavy-duty electrically operated switch that connects the pack to the vehicle or inverter and opens it on fault or shutdown. Packs use at least two, one per pole, plus a pre-charge path to avoid welding them on the first connection.",
        "related": [
          "pre-charge",
          "battery-disconnect-unit",
          "pyrofuse",
          "bms"
        ],
        "url": "https://lemonergy.com/learn/glossary/contactor/",
        "mentions": [
          "inverter"
        ]
      }
    },
    {
      "id": "term:can-bus",
      "type": "Term",
      "label": "CAN bus",
      "properties": {
        "id": "can-bus",
        "name": "CAN bus",
        "aka": [
          "Controller Area Network",
          "ISO 11898"
        ],
        "section": "topic-pack",
        "definition": "The serial network over which a BMS talks to the vehicle or inverter: a two-wire differential bus, defined in ISO 11898, carrying short prioritised messages at up to 1 Mbit/s, or faster with CAN FD. Every node hears every message, and a dominant bit wins arbitration without any collision.",
        "related": [
          "can-high-low",
          "can-fd",
          "termination-resistor",
          "bms",
          "lin-bus",
          "fms-interface"
        ],
        "url": "https://lemonergy.com/learn/glossary/can-bus/",
        "mentions": [
          "inverter"
        ]
      }
    },
    {
      "id": "term:bms-power-modes",
      "type": "Term",
      "label": "BMS power modes",
      "properties": {
        "id": "bms-power-modes",
        "name": "BMS power modes",
        "aka": [
          "sleep mode",
          "active mode",
          "standby mode",
          "wake-up"
        ],
        "section": "topic-data",
        "definition": "The states a BMS moves between to save energy. In active mode it measures, estimates and drives the contactors; asleep it draws microamperes to a few milliamperes from the auxiliary battery and wakes on CAN traffic, ignition, a charger plug or a timer to check cells and balance. Sleep current decides how long a parked vehicle can stand.",
        "related": [
          "bms",
          "auxiliary-battery",
          "can-bus",
          "cell-balancing",
          "self-discharge"
        ],
        "url": "https://lemonergy.com/learn/glossary/bms-power-modes/",
        "mentions": [
          "charger"
        ]
      }
    },
    {
      "id": "term:datasheet",
      "type": "Term",
      "label": "Datasheet",
      "properties": {
        "id": "datasheet",
        "name": "Datasheet",
        "section": "topic-ratings",
        "definition": "The manufacturer’s specification sheet for a cell: nominal capacity, nominal voltage, voltage window, continuous and peak currents, operating temperatures, dimensions, mass and cycle life, each tied to the test conditions it was measured under.",
        "related": [
          "nominal-capacity",
          "nominal-voltage",
          "operating-temperature",
          "cycle-life",
          "iec-62620"
        ],
        "lesson": "fundamentals/battery-basics/#datasheet",
        "url": "https://lemonergy.com/learn/glossary/datasheet/",
        "mentions": [
          "voltage-window"
        ]
      }
    }
  ]
}