{ "node": { "id": "term:nominal-voltage", "type": "Term", "label": "Nominal voltage", "properties": { "id": "nominal-voltage", "name": "Nominal voltage", "section": "topic-ratings", "definition": "A representative average voltage of a cell over a full discharge, such as 3.6–3.7 V for an oxide/graphite cell or about 3.2 V for LFP/graphite. Multiplied by capacity, it gives nominal energy.", "unit": "V", "related": [ "nominal-energy", "open-circuit-voltage", "voltage-window", "lfp" ], "lesson": "fundamentals/capacity-and-c-rate/#energy", "url": "https://lemonergy.com/learn/glossary/nominal-voltage/", "mentions": [ "graphite" ] } }, "edges": [ { "id": "edge:12", "source": "term:nominal-voltage", "target": "workflow:nominal-energy", "type": "usedIn", "properties": { "sourceFile": "wiki-blocks.json" } }, { "id": "edge:908", "source": "term:nominal-voltage", "target": "topic:topic-ratings", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:909", "source": "term:nominal-voltage", "target": "term:nominal-energy", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:910", "source": "term:nominal-voltage", "target": "term:open-circuit-voltage", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:911", "source": "term:nominal-voltage", "target": "term:voltage-window", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:912", "source": "term:nominal-voltage", "target": "term:lfp", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:mentions/nominal-voltage/graphite", "source": "term:nominal-voltage", "target": "term:graphite", "type": "mentions", "properties": { "sourceFile": "terms.json", "method": "build_glossary.mention_index + mentions", "field": "definition", "meaning": "Text mention; not a causal claim" } }, { "id": "edge:914", "source": "term:nominal-voltage", "target": "lesson:fundamentals/capacity-and-c-rate/", "type": "explainedIn", "properties": { "sourceFile": "terms.json", "url": "https://lemonergy.com/learn/fundamentals/capacity-and-c-rate/#energy" } }, { "id": "edge:915", "source": "term:nominal-voltage", "target": "visual:voltage", "type": "illustratedBy", "properties": { "sourceFile": "visual-pages.json" } } ], "neighbors": [ { "id": "workflow:nominal-energy", "type": "Workflow", "label": "Estimate nominal energy", "properties": { "id": "nominal-energy", "title": "Estimate nominal energy", "kind": "core", "summary": "Lemonergy Core evaluates this relation.", "steps": [ "Open the lesson and inspect the equation.", "Change one input while holding the others fixed." ], "example": "A 5 Ah cell rated 3.6 V has 18 Wh nominal energy. Ten identical cells contain 180 Wh nominally.", "observe": "Compare the result with the equation and units.", "limits": "This is a rating estimate, not integrated delivered terminal energy.", "url": "https://lemonergy.com/learn/fundamentals/capacity-and-c-rate/#energy", "label": "Open the worked lesson", "evidence": [ "src/battery_core/capacity.py" ] } }, { "id": "topic:topic-ratings", "type": "Topic", "label": "Capacity, energy, power and ratings", "properties": { "id": "topic-ratings", "name": "Capacity, energy, power and ratings", "lede": "The numbers that size a cell and let two cells be compared.", "context": "Separate nameplate ratings from test results.", "example": "5 Ah at 3.6 V gives 18 Wh nominally. Integrated measured terminal power may give a different result.", "lesson_url": "https://lemonergy.com/learn/fundamentals/capacity-and-c-rate/", "lesson_label": "Open capacity and C-rate" } }, { "id": "term:nominal-energy", "type": "Term", "label": "Nominal energy", "properties": { "id": "nominal-energy", "name": "Nominal energy", "section": "topic-ratings", "definition": "Nominal capacity times nominal voltage, in watt-hours: the headline energy figure on a datasheet. The energy actually delivered depends on the load, the temperature and how the voltage curve is weighted.", "formula": "E = Q × V_nominal", "unit": "Wh", "related": [ "nominal-capacity", "nominal-voltage", "watt-hour", "energy-density" ], "lesson": "fundamentals/capacity-and-c-rate/#energy", "example": { "title": "Turn capacity into a nominal energy", "text": "A 5 Ah cell with a nominal voltage of 3.6 V has 18 Wh of nominal energy. This estimate uses the nominal voltage; delivered energy is the integral of measured terminal voltage multiplied by current." }, "url": "https://lemonergy.com/learn/glossary/nominal-energy/", "mentions": [ "datasheet", "discharge-curve" ] } }, { "id": "term:open-circuit-voltage", "type": "Term", "label": "Open-circuit voltage", "properties": { "id": "open-circuit-voltage", "name": "Open-circuit voltage", "abbr": "OCV", "section": "topic-state", "definition": "The voltage across a cell’s terminals when no current flows and the cell has rested long enough for the voltage to settle. It depends on state of charge and temperature, and a cell whose open-circuit voltage falls unusually fast in storage may have an internal short.", "unit": "V", "related": [ "ocv-soc-curve", "relaxation", "voltage-hysteresis", "k-value", "internal-short-circuit" ], "lesson": "fundamentals/cell-production/#finishing", "url": "https://lemonergy.com/learn/glossary/open-circuit-voltage/", "mentions": [ "state-of-charge" ] } }, { "id": "term:voltage-window", "type": "Term", "label": "Voltage window", "properties": { "id": "voltage-window", "name": "Voltage window", "aka": [ "operating voltage range" ], "section": "topic-ratings", "definition": "The range between a cell’s lower and upper cutoff voltages, such as 2.5–4.2 V for an NMC/graphite cell. Staying inside it is what keeps the electrodes and electrolyte from degrading quickly.", "unit": "V", "related": [ "cutoff-voltage", "overcharge", "over-discharge", "electrochemical-stability-window" ], "url": "https://lemonergy.com/learn/glossary/voltage-window/", "mentions": [ "graphite", "electrolyte" ] } }, { "id": "term:lfp", "type": "Term", "label": "LFP", "properties": { "id": "lfp", "name": "LFP", "aka": [ "lithium iron phosphate", "LiFePO₄" ], "section": "topic-chemistries", "definition": "A positive electrode material, LiFePO₄, giving cells a nominal voltage around 3.2 V, long cycle life and good thermal stability, but less energy per kilogram than nickel-rich oxides. Its flat voltage curve makes state of charge hard to read from voltage alone.", "related": [ "cathode-active-material", "nmc", "lmfp", "ocv-soc-curve", "cycle-life" ], "lesson": "fundamentals/cell-anatomy/#voltage", "example": { "title": "Chemistry is not the whole datasheet", "text": "Two LFP products can differ in format, loading, capacity and current limits. Their cathode family alone does not make them interchangeable." }, "url": "https://lemonergy.com/learn/glossary/lfp/", "mentions": [ "electrode", "positive-electrode", "nominal-voltage", "discharge-curve", "state-of-charge" ] } }, { "id": "term:graphite", "type": "Term", "label": "Graphite", "properties": { "id": "graphite", "name": "Graphite", "section": "topic-components", "definition": "Layered carbon, the negative active material of nearly all lithium-ion cells. Lithium intercalates between its layers up to LiC₆, a theoretical 372 mAh/g, at a potential about 0.1 V above lithium metal.", "related": [ "anode-active-material", "intercalation", "natural-graphite", "synthetic-graphite", "lithium-plating" ], "lesson": "fundamentals/cell-anatomy/#components", "example": { "title": "Compare matching mass bases", "text": "A graphite value per gram of active material cannot be directly compared with a value including binder, additive and foil." }, "url": "https://lemonergy.com/learn/glossary/graphite/", "mentions": [ "milliampere-hour", "active-material" ] } }, { "id": "lesson:fundamentals/capacity-and-c-rate/", "type": "Lesson", "label": "Lesson 2 · Capacity and C-rate", "properties": { "url": "https://lemonergy.com/learn/fundamentals/capacity-and-c-rate/" } }, { "id": "visual:voltage", "type": "Visual", "label": "Voltage under load", "properties": { "title": "Voltage under load", "summary": "Discharge current creates an ohmic drop below open-circuit voltage.", "readout": "5 A through 20 mΩ gives 0.1 V ohmic drop.", "formula": "V_terminal = OCV − I_discharge R", "note": "Chosen OCV curve; no chemistry calibration, hysteresis or voltage cutoff.", "software": { "status": "studio", "label": "Voltage relationship in Studio", "body": "The native battery calculates terminal voltage from OCV and resistance. The curve here is an illustrative OCV relationship, not a fitted cell dataset.", "href": "https://design.lemonergy.com/cosim.html?example=charging-home" }, "html": "
Illustrative OCV and loaded voltage
Illustrative OCV and loaded voltageSOC (%) versus Voltage (V). Open circuit; Under load. Interpretation follows the graphs.1.802.42253.05503.67754.3100SOC (%)Voltage (V)
Open circuitUnder load (dashed)
" } } ] }