{ "node": { "id": "term:power", "type": "Term", "label": "Power", "properties": { "id": "power", "name": "Power", "section": "topic-units", "definition": "The rate at which a cell delivers or absorbs energy: voltage times current, in watts. Power is limited by internal resistance and temperature long before capacity runs out.", "formula": "P = V × I", "unit": "W", "related": [ "watt", "specific-power", "state-of-power", "internal-resistance" ], "example": { "title": "Separate power from energy", "text": "A 100 W load running for 30 min uses 50 Wh. Power tells you how fast energy is transferred; the duration determines how much energy is transferred." }, "url": "https://lemonergy.com/learn/glossary/power/", "mentions": [] } }, "edges": [ { "id": "edge:56", "source": "term:power", "target": "workflow:loss-accounting", "type": "usedIn", "properties": { "sourceFile": "wiki-blocks.json" } }, { "id": "edge:229", "source": "term:power", "target": "topic:topic-units", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:230", "source": "term:power", "target": "term:watt", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:231", "source": "term:power", "target": "term:specific-power", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:232", "source": "term:power", "target": "term:state-of-power", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:233", "source": "term:power", "target": "term:internal-resistance", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:234", "source": "term:power", "target": "visual:energy", "type": "illustratedBy", "properties": { "sourceFile": "visual-pages.json" } }, { "id": "edge:235", "source": "term:power", "target": "reference:bipm-si", "type": "cites", "properties": { "sourceFile": "wiki-references.json", "scope": "direct technical reference" } } ], "neighbors": [ { "id": "workflow:loss-accounting", "type": "Workflow", "label": "Compare grid and battery energy", "properties": { "id": "loss-accounting", "title": "Compare grid and battery energy", "kind": "studio", "summary": "Separate energy and loss signals make efficiency visible.", "steps": [ "Keep battery settings fixed.", "Change converter efficiency." ], "example": "7 kW battery-side power at 95% efficiency requires about 7.37 kW grid power and produces about 0.37 kW converter loss.", "observe": "Battery I²R loss differs from converter loss.", "limits": "A loss signal is not a predicted temperature. This network takes external temperature.", "url": "https://design.lemonergy.com/cosim.html?example=charging-home", "label": "Open the Studio example", "evidence": [ "js/charging-control.js", "js/charging-scenarios.js", "docs/CHARGING_BLOCKS_SPEC.md" ] } }, { "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", "type": "Term", "label": "Watt", "properties": { "id": "watt", "name": "Watt", "abbr": "W", "section": "topic-units", "definition": "The SI unit of power: one joule per second, or in a circuit, volts times amperes. A cell delivering 20 A at 3.6 V is supplying 72 W.", "formula": "P = V × I", "unit": "W", "related": [ "power", "watt-hour", "specific-power" ], "example": { "title": "Calculate electrical power", "text": "At a particular instant, a terminal voltage of 12 V and current magnitude of 3 A correspond to 36 W. State whether the battery is receiving or supplying that power." }, "url": "https://lemonergy.com/learn/glossary/watt/", "mentions": [ "joule" ] } }, { "id": "term:specific-power", "type": "Term", "label": "Specific power", "properties": { "id": "specific-power", "name": "Specific power", "aka": [ "power density" ], "section": "topic-ratings", "definition": "Deliverable power per unit mass, in watts per kilogram; power density is the same per litre. A cell is designed for energy or for power, rarely both: thin electrodes give power, thick ones give energy.", "unit": "W/kg", "related": [ "power", "specific-energy", "ragone-plot", "areal-loading", "power-cell-energy-cell" ], "url": "https://lemonergy.com/learn/glossary/specific-power/", "mentions": [] } }, { "id": "term:state-of-power", "type": "Term", "label": "State of power", "properties": { "id": "state-of-power", "name": "State of power", "abbr": "SOP", "section": "topic-state", "definition": "The maximum charge or discharge power a battery can deliver for the next few seconds without breaking a voltage, current or temperature limit. The BMS recomputes it continuously from SOC, temperature and resistance and sends it to the motor controller.", "unit": "W", "related": [ "power", "state-of-charge", "continuous-current", "derating", "bms", "state-of-function" ], "url": "https://lemonergy.com/learn/glossary/state-of-power/", "mentions": [] } }, { "id": "term:internal-resistance", "type": "Term", "label": "Internal resistance", "properties": { "id": "internal-resistance", "name": "Internal resistance", "abbr": "IR", "aka": [ "DC resistance", "DCIR" ], "section": "topic-units", "definition": "The resistance a cell presents to current, from its foils, electrolyte, interfaces and the reactions themselves. It converts part of the delivered energy into heat, sets the voltage drop under load, and rises as the cell ages; a large automotive cell has about a milliohm, a small cylindrical cell tens.", "unit": "mΩ", "related": [ "ohms-law", "ir-drop", "impedance-rise", "dcir", "area-specific-resistance", "resistance-capacity-product" ], "lesson": "fundamentals/battery-basics/#datasheet", "url": "https://lemonergy.com/learn/glossary/internal-resistance/", "mentions": [ "electrolyte", "cylindrical-cell" ] } }, { "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" } } ] }