{ "node": { "id": "term:nominal-capacity", "type": "Term", "label": "Nominal capacity", "properties": { "id": "nominal-capacity", "name": "Nominal capacity", "aka": [ "rated capacity" ], "section": "topic-ratings", "definition": "The charge a cell is rated to deliver under specified test conditions — current, temperature, rest and voltage limits — usually in ampere-hours.", "unit": "Ah", "related": [ "ampere-hour", "c-rate", "capacity-test", "usable-capacity", "state-of-health" ], "lesson": "fundamentals/capacity-and-c-rate/#nominal-capacity", "url": "https://lemonergy.com/learn/glossary/nominal-capacity/", "mentions": [] } }, "edges": [ { "id": "edge:3", "source": "term:nominal-capacity", "target": "workflow:c-rate", "type": "usedIn", "properties": { "sourceFile": "wiki-blocks.json" } }, { "id": "edge:854", "source": "term:nominal-capacity", "target": "topic:topic-ratings", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:855", "source": "term:nominal-capacity", "target": "term:ampere-hour", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:856", "source": "term:nominal-capacity", "target": "term:c-rate", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:857", "source": "term:nominal-capacity", "target": "term:capacity-test", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:858", "source": "term:nominal-capacity", "target": "term:usable-capacity", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:859", "source": "term:nominal-capacity", "target": "term:state-of-health", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:860", "source": "term:nominal-capacity", "target": "lesson:fundamentals/capacity-and-c-rate/", "type": "explainedIn", "properties": { "sourceFile": "terms.json", "url": "https://lemonergy.com/learn/fundamentals/capacity-and-c-rate/#nominal-capacity" } }, { "id": "edge:861", "source": "term:nominal-capacity", "target": "visual:capacity", "type": "illustratedBy", "properties": { "sourceFile": "visual-pages.json" } }, { "id": "edge:862", "source": "term:nominal-capacity", "target": "reference:inl-ev-tests", "type": "cites", "properties": { "sourceFile": "wiki-references.json", "scope": "direct technical reference" } }, { "id": "edge:863", "source": "term:nominal-capacity", "target": "reference:sandia-performance", "type": "cites", "properties": { "sourceFile": "wiki-references.json", "scope": "direct technical reference" } } ], "neighbors": [ { "id": "workflow:c-rate", "type": "Workflow", "label": "Convert C-rate into current", "properties": { "id": "c-rate", "title": "Convert C-rate into current", "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 at 0.5C corresponds to 2.5 A. At 2C it corresponds to 10 A.", "observe": "Compare the result with the equation and units.", "limits": "Current magnitudes do not establish safe charge rates.", "url": "https://lemonergy.com/learn/fundamentals/capacity-and-c-rate/", "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:ampere-hour", "type": "Term", "label": "Ampere-hour", "properties": { "id": "ampere-hour", "name": "Ampere-hour", "abbr": "Ah", "aka": [ "amp-hour" ], "section": "topic-units", "definition": "A unit of electric charge: one ampere flowing for one hour, or 3600 coulombs. Battery capacity is rated in ampere-hours, which measure charge, not energy.", "unit": "Ah", "related": [ "nominal-capacity", "milliampere-hour", "watt-hour" ], "lesson": "fundamentals/capacity-and-c-rate/#nominal-capacity", "url": "https://lemonergy.com/learn/glossary/ampere-hour/", "mentions": [ "ampere", "electric-charge" ] } }, { "id": "term:c-rate", "type": "Term", "label": "C-rate", "properties": { "id": "c-rate", "name": "C-rate", "section": "topic-ratings", "definition": "Current divided by nominal capacity, in reciprocal hours. 1C on a 20 Ah cell is 20 A; 2C is 40 A. C-rate lets you compare loads on cells of different sizes.", "formula": "C-rate = I / Q_nominal", "unit": "h⁻¹", "related": [ "nominal-capacity", "ideal-duration", "current", "e-rate", "fast-charging" ], "lesson": "fundamentals/capacity-and-c-rate/#c-rate", "example": { "title": "Convert a rating into amperes", "text": "For a 5 Ah cell, 0.5C means 2.5 A, 1C means 5 A and 2C means 10 A. Dividing 2.5 A by 5 Ah returns 0.5 h⁻¹, conventionally written 0.5C." }, "url": "https://lemonergy.com/learn/glossary/c-rate/", "mentions": [] } }, { "id": "term:capacity-test", "type": "Term", "label": "Capacity test", "properties": { "id": "capacity-test", "name": "Capacity test", "section": "topic-testing", "definition": "A defined capacity test with specified charge, rest, discharge and cutoff conditions, usually a full CC-CV charge, a rest, and a C/3 or lower discharge to the lower cutoff at 25 °C. The delivered ampere-hours are the cell’s measured capacity.", "related": [ "nominal-capacity", "cc-cv-charging", "cutoff-voltage", "reference-performance-test", "rate-test" ], "lesson": "fundamentals/capacity-and-c-rate/#nominal-capacity", "url": "https://lemonergy.com/learn/glossary/capacity-test/", "mentions": [] } }, { "id": "term:usable-capacity", "type": "Term", "label": "Usable capacity", "properties": { "id": "usable-capacity", "name": "Usable capacity", "aka": [ "available capacity" ], "section": "topic-ratings", "definition": "The part of a cell’s capacity that a system actually lets it use, after the BMS reserves margins at the top and bottom of the state-of-charge window. An electric-car pack may use 90–95 % of its gross capacity.", "related": [ "nominal-capacity", "depth-of-discharge", "state-of-charge", "bms" ], "url": "https://lemonergy.com/learn/glossary/usable-capacity/", "mentions": [] } }, { "id": "term:state-of-health", "type": "Term", "label": "State of health", "properties": { "id": "state-of-health", "name": "State of health", "abbr": "SOH", "section": "topic-state", "definition": "A summary of how far a cell has aged, often expressed through remaining capacity or increased resistance compared with when it was new. By convention a cell has reached end of life at 80 % of its rated capacity.", "unit": "%", "related": [ "capacity-fade", "impedance-rise", "end-of-life", "remaining-useful-life", "state-of-charge", "state-of-certified-energy" ], "lesson": "fundamentals/capacity-and-c-rate/#real-cells", "url": "https://lemonergy.com/learn/glossary/state-of-health/", "mentions": [ "nominal-capacity" ] } }, { "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:capacity", "type": "Visual", "label": "C-rate, current and duration", "properties": { "title": "C-rate, current and duration", "summary": "A C-rate becomes an actual current only when capacity is known.", "readout": "5 Ah × 1C = 5 A. Ideal duration: 1 h (60 min).", "formula": "I = Q × C-rate; t_ideal = 1 / C-rate", "note": "Voltage cutoff, losses, temperature and rate-dependent capacity are excluded.", "software": { "status": "implemented", "label": "Implemented in battery-core", "body": "current_from_c_rate calculates I = Q × C-rate; ideal_duration_hours calculates 1 / C-rate. Neither predicts voltage-cutoff time or real usable capacity.", "href": "../fundamentals/capacity-and-c-rate/" }, "html": "
Ideal remaining charge
Ideal remaining chargeTime (h) versus Remaining charge (Ah). 1C. Interpretation follows the graphs.001.2512.523.75354Time (h)Remaining charge (Ah)
1C
" } }, { "id": "reference:inl-ev-tests", "type": "Reference", "label": "Battery Test Manual For Electric Vehicles, Revision 3", "properties": { "title": "Battery Test Manual For Electric Vehicles, Revision 3", "publisher": "Idaho National Laboratory", "url": "https://inldigitallibrary.inl.gov/sites/sti/sti/6492291.pdf", "type": "Test manual", "scope": "Performance characterization, pulse resistance/power, life testing and reference performance tests; historical 2015 edition.", "year": 2015, "authors": [ "Jon P. Christopherson" ], "accessed": "2026-10-27" } }, { "id": "reference:sandia-performance", "type": "Reference", "label": "DOE Energy Storage Handbook, Chapter 16: Energy Storage Performance Testing", "properties": { "title": "DOE Energy Storage Handbook, Chapter 16: Energy Storage Performance Testing", "publisher": "Sandia National Laboratories", "url": "https://www.sandia.gov/app/uploads/sites/163/2021/09/ESHB_Ch16_Testing_Rosewater.pdf", "type": "Technical handbook chapter", "scope": "Section 2.1.2.1 explains capacity, C-rate and the distinction between capacity and energy; also covers pulse characterization.", "accessed": "2026-10-27" } } ] }