{ "node": { "id": "term:kilowatt-hour", "type": "Term", "label": "Kilowatt-hour", "properties": { "id": "kilowatt-hour", "name": "Kilowatt-hour", "abbr": "kWh", "section": "topic-units", "definition": "One thousand watt-hours, the unit for pack and system energy. An electric car carries 40–100 kWh; grid storage is quoted in megawatt-hours (1000 kWh) and factory output in gigawatt-hours per year.", "unit": "kWh", "related": [ "watt-hour", "nominal-energy", "cost-per-kwh", "gigafactory" ], "url": "https://lemonergy.com/learn/glossary/kilowatt-hour/", "mentions": [] } }, "edges": [ { "id": "edge:14", "source": "term:kilowatt-hour", "target": "workflow:nominal-energy", "type": "usedIn", "properties": { "sourceFile": "wiki-blocks.json" } }, { "id": "edge:245", "source": "term:kilowatt-hour", "target": "topic:topic-units", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:246", "source": "term:kilowatt-hour", "target": "term:watt-hour", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:247", "source": "term:kilowatt-hour", "target": "term:nominal-energy", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:248", "source": "term:kilowatt-hour", "target": "term:cost-per-kwh", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:249", "source": "term:kilowatt-hour", "target": "term:gigafactory", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:250", "source": "term:kilowatt-hour", "target": "visual:energy", "type": "illustratedBy", "properties": { "sourceFile": "visual-pages.json" } }, { "id": "edge:251", "source": "term:kilowatt-hour", "target": "reference:bipm-si", "type": "cites", "properties": { "sourceFile": "wiki-references.json", "scope": "direct technical reference" } } ], "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-units", "type": "Topic", "label": "Units and electrical basics", "properties": { "id": "topic-units", "name": "Units and electrical basics", "lede": "The quantities every datasheet is written in, and how they relate.", "context": "Use consistent units and cell/pack basis.", "example": "10 A for 30 min transfers 5 Ah. At constant 3.6 V this is 18 Wh; varying voltage requires integration.", "lesson_url": "https://lemonergy.com/learn/fundamentals/capacity-and-c-rate/", "lesson_label": "Open capacity and C-rate" } }, { "id": "term:watt-hour", "type": "Term", "label": "Watt-hour", "properties": { "id": "watt-hour", "name": "Watt-hour", "abbr": "Wh", "section": "topic-units", "definition": "A unit of energy: one watt for one hour, or 3600 joules. A cell’s nominal energy in watt-hours is its capacity in ampere-hours times its nominal voltage — 20 Ah at 3.65 V is 73 Wh.", "formula": "E = Q × V", "unit": "Wh", "related": [ "nominal-energy", "kilowatt-hour", "ampere-hour", "nominal-voltage" ], "lesson": "fundamentals/capacity-and-c-rate/#energy", "example": { "title": "Compare a Wh rating with Ah", "text": "A nominal 3.6 V, 5 Ah cell is rated at approximately 18 Wh. Watt-hours measure energy, while ampere-hours measure charge; the voltage is needed to convert between them." }, "url": "https://lemonergy.com/learn/glossary/watt-hour/", "mentions": [ "watt" ] } }, { "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:cost-per-kwh", "type": "Term", "label": "Cost per kilowatt-hour", "properties": { "id": "cost-per-kwh", "name": "Cost per kilowatt-hour", "section": "topic-applications", "definition": "The headline price of cells or packs per unit of nominal energy. Pack prices fell by about 90 % between 2010 and the mid-2020s to roughly 100 US dollars per kWh, with LFP cells in China well below that.", "unit": "$/kWh", "related": [ "kilowatt-hour", "yield", "levelized-cost-of-storage", "lfp" ], "url": "https://lemonergy.com/learn/glossary/cost-per-kwh/", "mentions": [ "nominal-energy" ] } }, { "id": "term:gigafactory", "type": "Term", "label": "Gigafactory", "properties": { "id": "gigafactory", "name": "Gigafactory", "section": "topic-manufacturing", "definition": "A cell plant with an annual output of at least a few gigawatt-hours, enough for tens of thousands of electric cars. The term began as one company’s name for its plant and is now used for any large battery factory.", "unit": "GWh/year", "related": [ "cell-production", "kilowatt-hour", "yield", "cost-per-kwh" ], "url": "https://lemonergy.com/learn/glossary/gigafactory/", "mentions": [] } }, { "id": "visual:energy", "type": "Visual", "label": "From charge to energy", "properties": { "title": "From charge to energy", "summary": "Voltage connects capacity in ampere-hours to nominal energy in watt-hours.", "readout": "5 Ah × 12 V = 60 Wh nominal energy.", "formula": "E_nominal = Q_nominal V_nominal; actual energy = ∫ VI dt", "note": "Specific energy divides energy by mass; energy density divides it by volume.", "software": { "status": "implemented", "label": "Implemented in battery-core", "body": "nominal_energy_wh multiplies nominal voltage by capacity. Actual discharge energy requires the integral of voltage × current.", "href": "../fundamentals/capacity-and-c-rate/" }, "html": "
Nominal energy versus capacity
Nominal energy versus capacityCapacity (Ah) versus Energy (Wh). 12 V rating. Interpretation follows the graphs.00605120101801524020Capacity (Ah)Energy (Wh)
12 V rating
" } }, { "id": "reference:bipm-si", "type": "Reference", "label": "The International System of Units (SI), 9th edition", "properties": { "title": "The International System of Units (SI), 9th edition", "publisher": "Bureau International des Poids et Mesures", "url": "https://doi.org/10.59161/AUEZ1291", "type": "Metrology reference", "scope": "Definitions of SI units and coherent derived units; 2026 revision.", "year": 2026, "accessed": "2026-10-27" } } ] }