{ "node": { "id": "term:e-rate", "type": "Term", "label": "E-rate", "properties": { "id": "e-rate", "name": "E-rate", "aka": [ "P-rate" ], "section": "topic-ratings", "definition": "Power divided by nominal energy, the energy-based cousin of the C-rate: a 1E discharge empties a cell’s watt-hours in one hour. Grid-storage contracts are often written in E-rates or hours of discharge rather than in amperes.", "formula": "E-rate = P / E_nominal", "unit": "h⁻¹", "related": [ "c-rate", "nominal-energy", "stationary-storage" ], "example": { "title": "Convert energy rating to power", "text": "A 20 kWh battery delivering 10 kW operates at 0.5 h⁻¹, conventionally 0.5E. At constant power with ideal full energy availability, the corresponding duration is 2 h." }, "url": "https://lemonergy.com/learn/glossary/e-rate/", "mentions": [] } }, "edges": [ { "id": "edge:903", "source": "term:e-rate", "target": "topic:topic-ratings", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:904", "source": "term:e-rate", "target": "term:c-rate", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:905", "source": "term:e-rate", "target": "term:nominal-energy", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:906", "source": "term:e-rate", "target": "term:stationary-storage", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:907", "source": "term:e-rate", "target": "visual:energy", "type": "illustratedBy", "properties": { "sourceFile": "visual-pages.json" } } ], "neighbors": [ { "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: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: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:stationary-storage", "type": "Term", "label": "Stationary storage", "properties": { "id": "stationary-storage", "name": "Stationary storage", "abbr": "BESS", "aka": [ "battery energy storage system", "ESS" ], "section": "topic-applications", "definition": "Batteries installed in a fixed place — a container at a solar farm, a cabinet in a home — to shift energy in time or support the grid. LFP cells dominate because cost per cycle and safety matter more than mass.", "related": [ "lfp", "energy-management-system", "inverter", "energy-arbitrage", "long-duration-storage", "ul-9540a" ], "url": "https://lemonergy.com/learn/glossary/stationary-storage/", "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
" } } ] }