{ "node": { "id": "term:coulomb", "type": "Term", "label": "Coulomb", "properties": { "id": "coulomb", "name": "Coulomb", "abbr": "C", "section": "topic-units", "definition": "The SI unit of electric charge; one ampere flowing for one second. Battery engineers prefer the ampere-hour, which is 3600 coulombs, because cells deliver their charge over hours.", "unit": "C", "related": [ "ampere-hour", "faradays-constant" ], "url": "https://lemonergy.com/learn/glossary/coulomb/", "mentions": [ "ampere", "electric-charge" ] } }, "edges": [ { "id": "edge:200", "source": "term:coulomb", "target": "topic:topic-units", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:201", "source": "term:coulomb", "target": "term:ampere-hour", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:202", "source": "term:coulomb", "target": "term:faradays-constant", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:mentions/coulomb/ampere", "source": "term:coulomb", "target": "term:ampere", "type": "mentions", "properties": { "sourceFile": "terms.json", "method": "build_glossary.mention_index + mentions", "field": "definition", "meaning": "Text mention; not a causal claim" } }, { "id": "edge:mentions/coulomb/electric-charge", "source": "term:coulomb", "target": "term:electric-charge", "type": "mentions", "properties": { "sourceFile": "terms.json", "method": "build_glossary.mention_index + mentions", "field": "definition", "meaning": "Text mention; not a causal claim" } }, { "id": "edge:205", "source": "term:coulomb", "target": "visual:capacity", "type": "illustratedBy", "properties": { "sourceFile": "visual-pages.json" } }, { "id": "edge:206", "source": "term:coulomb", "target": "reference:bipm-si", "type": "cites", "properties": { "sourceFile": "wiki-references.json", "scope": "direct technical reference" } } ], "neighbors": [ { "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: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:faradays-constant", "type": "Term", "label": "Faraday’s constant", "properties": { "id": "faradays-constant", "name": "Faraday’s constant", "abbr": "F", "section": "topic-electrochemistry", "definition": "The charge carried by one mole of electrons, 96 485 coulombs or 26.8 ampere-hours. It links the moles of lithium that move in a reaction to the ampere-hours a cell delivers.", "unit": "C/mol", "related": [ "faradays-law", "theoretical-capacity", "coulomb", "ampere-hour" ], "url": "https://lemonergy.com/learn/glossary/faradays-constant/", "mentions": [] } }, { "id": "term:ampere", "type": "Term", "label": "Ampere", "properties": { "id": "ampere", "name": "Ampere", "abbr": "A", "section": "topic-units", "definition": "The SI unit of electric current: one coulomb of charge passing a point per second. Cell currents are quoted in amperes, or as a C-rate so cells of different size can be compared.", "unit": "A", "related": [ "coulomb", "c-rate", "current" ], "url": "https://lemonergy.com/learn/glossary/ampere/", "mentions": [] } }, { "id": "term:electric-charge", "type": "Term", "label": "Electric charge", "properties": { "id": "electric-charge", "name": "Electric charge", "abbr": "Q", "section": "topic-units", "definition": "The quantity a battery’s capacity actually counts: how many electrons, or lithium ions, have passed. It is measured in coulombs or ampere-hours and is conserved, which is why charge in must equal charge out plus losses.", "unit": "C, Ah", "related": [ "ampere-hour", "coulomb", "coulombic-efficiency", "nominal-capacity" ], "url": "https://lemonergy.com/learn/glossary/electric-charge/", "mentions": [] } }, { "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: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" } } ] }