{ "node": { "id": "term:bms-architecture", "type": "Term", "label": "BMS architecture", "properties": { "id": "bms-architecture", "name": "BMS architecture", "aka": [ "centralised BMS", "centralized BMS", "distributed BMS", "modular BMS", "master–slave BMS", "rack BMS" ], "section": "topic-pack", "definition": "How a BMS’s electronics are divided across the pack. A centralised BMS wires every cell to one board, suiting small packs; a modular or master–slave design puts a monitoring board on each module reporting to one controller; a distributed design puts electronics on each cell. Stationary systems add tiers: module, rack and system-level BMS.", "related": [ "bms", "cell-supervision-circuit", "bmu", "wireless-bms", "string", "redundant-bms" ], "url": "https://lemonergy.com/learn/glossary/bms-architecture/", "mentions": [] } }, "edges": [ { "id": "edge:4987", "source": "term:bms-architecture", "target": "topic:topic-pack", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:4988", "source": "term:bms-architecture", "target": "term:bms", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:4989", "source": "term:bms-architecture", "target": "term:cell-supervision-circuit", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:4990", "source": "term:bms-architecture", "target": "term:bmu", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:4991", "source": "term:bms-architecture", "target": "term:wireless-bms", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:4992", "source": "term:bms-architecture", "target": "term:string", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:4993", "source": "term:bms-architecture", "target": "term:redundant-bms", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:4994", "source": "term:bms-architecture", "target": "visual:balancing", "type": "illustratedBy", "properties": { "sourceFile": "visual-pages.json" } } ], "neighbors": [ { "id": "topic:topic-pack", "type": "Topic", "label": "Modules, packs and battery management", "properties": { "id": "topic-pack", "name": "Modules, packs and battery management", "lede": "From a single cell to a working battery system, and the electronics that keep it safe.", "context": "Make series/parallel architecture explicit.", "example": "Twelve 3.6 V, 5 Ah cells in 6s2p give 21.6 V, 10 Ah and 216 Wh nominally before other restrictions.", "lesson_url": "https://lemonergy.com/learn/fundamentals/cell-architecture/", "lesson_label": "Open cell architecture" } }, { "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: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:wireless-bms", "type": "Term", "label": "Wireless BMS", "properties": { "id": "wireless-bms", "name": "Wireless BMS", "abbr": "wBMS", "section": "topic-pack", "definition": "A pack architecture in which each cell supervision circuit talks to the controller by radio instead of a wiring harness, saving cable, connectors and assembly time. It needs its own redundancy and security design to reach the same safety level.", "related": [ "cell-supervision-circuit", "bms", "isospi" ], "url": "https://lemonergy.com/learn/glossary/wireless-bms/", "mentions": [ "wiring-harness" ] } }, { "id": "term:string", "type": "Term", "label": "String", "properties": { "id": "string", "name": "String", "aka": [ "battery string", "series string" ], "section": "topic-pack", "definition": "A chain of cells or modules connected in series to reach the system voltage, the basic electrical unit of a large battery. In stationary storage each rack is usually one string of about 1000–1500 V with its own contactors and BMS, and many strings are paralleled on a common DC bus.", "related": [ "series-parallel", "pack-voltage", "stationary-storage", "parallel-string-current-sharing", "bms-architecture", "contactor" ], "url": "https://lemonergy.com/learn/glossary/string/", "mentions": [ "bms" ] } }, { "id": "term:redundant-bms", "type": "Term", "label": "Redundant BMS architecture", "properties": { "id": "redundant-bms", "name": "Redundant BMS architecture", "aka": [ "redundant BMS", "secondary safety monitor" ], "section": "topic-pack", "definition": "A BMS design that duplicates safety-critical functions so no single failure can hide a hazard: an independent second voltage monitor beside the main measurement chip, two current sensors of different principle, a watchdog or second processor, and two separate paths to open the contactors. It is how BMS hardware reaches ASIL C or D.", "related": [ "functional-safety", "bms-architecture", "hardware-safety-metrics", "lockstep-core", "current-sensor", "diagnostic-coverage" ], "url": "https://lemonergy.com/learn/glossary/redundant-bms/", "mentions": [ "bms" ] } }, { "id": "visual:balancing", "type": "Visual", "label": "The limiting cell matters", "properties": { "title": "The limiting cell matters", "summary": "A pack average can hide a cell that reaches its voltage limit first.", "readout": "Average: 3.93 V. Highest cell: 4.02 V. The highest cell can reach the charge limit first.", "formula": "V_max = max(V₁, V₂, …); V_average = ΣV_i / N", "note": "The 4.2 V ceiling is an example, not universal. Voltage alone does not uniquely determine SOC.", "software": { "status": "reference", "label": "Reference concept", "body": "Cell supervision uses individual voltages. The native Studio battery is an aggregate model; this chart does not claim it simulates cell balancing.", "href": "https://design.lemonergy.com/cosim.html?example=charging-home" }, "html": "
Four cells before balancing
Four cells before balancingCell number versus Cell voltage (V). Individual voltages; Average; Example ceiling. Interpretation follows the graphs.3.713.851.7542.54.153.254.34Cell numberCell voltage (V)
Individual voltagesAverage (dashed)Example ceiling
" } } ] }