{ "node": { "id": "term:resistance-capacity-product", "type": "Term", "label": "Resistance–capacity product", "properties": { "id": "resistance-capacity-product", "name": "Resistance–capacity product", "aka": [ "ohm-ampere-hour", "mΩ·Ah", "siemens per watt-hour", "S/Wh" ], "section": "topic-ratings", "definition": "A cell’s internal resistance multiplied by its capacity, which cancels out size: ten 5 Ah, 20 mΩ cells in parallel make 50 Ah at 2 mΩ, both 100 mΩ·Ah. Lower values mean more power per unit of stored energy. Conductance divided by energy, in siemens per watt-hour, expresses the same figure of merit the other way up.", "formula": "R·Q (mΩ·Ah); G/E = 1/(R·E) (S/Wh)", "unit": "mΩ·Ah", "related": [ "internal-resistance", "power-cell-energy-cell", "specific-power", "nominal-capacity", "siemens", "dcir" ], "example": { "title": "Compare two cell sizes", "text": "A 5 Ah cell with 20 mΩ resistance and a 10 Ah cell with 10 mΩ resistance both have RQ = 100 mΩ·Ah. Compare like test conditions; identical RQ does not imply identical chemistry or thermal behavior." }, "url": "https://lemonergy.com/learn/glossary/resistance-capacity-product/", "mentions": [ "watt-hour" ] } }, "edges": [ { "id": "edge:6136", "source": "term:resistance-capacity-product", "target": "topic:topic-ratings", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:6137", "source": "term:resistance-capacity-product", "target": "term:internal-resistance", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:6138", "source": "term:resistance-capacity-product", "target": "term:power-cell-energy-cell", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:6139", "source": "term:resistance-capacity-product", "target": "term:specific-power", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:6140", "source": "term:resistance-capacity-product", "target": "term:nominal-capacity", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:6141", "source": "term:resistance-capacity-product", "target": "term:siemens", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:6142", "source": "term:resistance-capacity-product", "target": "term:dcir", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:mentions/resistance-capacity-product/watt-hour", "source": "term:resistance-capacity-product", "target": "term:watt-hour", "type": "mentions", "properties": { "sourceFile": "terms.json", "method": "build_glossary.mention_index + mentions", "field": "definition", "meaning": "Text mention; not a causal claim" } }, { "id": "edge:6144", "source": "term:resistance-capacity-product", "target": "visual:parallel-normalization", "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: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": "term:power-cell-energy-cell", "type": "Term", "label": "Power cell and energy cell", "properties": { "id": "power-cell-energy-cell", "name": "Power cell and energy cell", "section": "topic-applications", "definition": "Two design points of the same chemistry: a power cell has thin, porous electrodes and many tabs for high current and fast charging; an energy cell has thick, dense electrodes for maximum watt-hours. A hybrid car wants the first, a long-range car the second.", "related": [ "specific-power", "specific-energy", "areal-loading", "cell-design" ], "url": "https://lemonergy.com/learn/glossary/power-cell-energy-cell/", "mentions": [ "fast-charging" ] } }, { "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: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": [] } }, { "id": "term:siemens", "type": "Term", "label": "Siemens", "properties": { "id": "siemens", "name": "Siemens", "abbr": "S", "section": "topic-units", "definition": "The SI unit of conductance, the reciprocal of the ohm. Electrolyte conductivity is quoted in millisiemens per centimetre; a good liquid electrolyte reaches about 10 mS/cm at room temperature.", "unit": "S", "related": [ "ionic-conductivity", "ohm" ], "url": "https://lemonergy.com/learn/glossary/siemens/", "mentions": [ "electrolyte" ] } }, { "id": "term:dcir", "type": "Term", "label": "DC internal resistance", "properties": { "id": "dcir", "name": "DC internal resistance", "abbr": "DCIR", "aka": [ "DC-IR", "pulse resistance" ], "section": "topic-testing", "definition": "Internal resistance measured from the voltage change during a current pulse of defined length, usually 10 s or 18 s. It is larger than the AC value because it includes charge-transfer and some diffusion, and it depends on SOC, temperature and pulse duration.", "unit": "mΩ", "related": [ "internal-resistance", "acir", "hppc", "impedance-rise" ], "url": "https://lemonergy.com/learn/glossary/dcir/", "mentions": [ "state-of-charge", "diffusion" ] } }, { "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": "visual:parallel-normalization", "type": "Visual", "label": "Parallel scaling preserves the resistance–capacity product", "properties": { "title": "Parallel scaling preserves the resistance–capacity product", "summary": "Identical parallel cells reduce resistance while adding capacity.", "readout": "R × Q remains 100 mΩ·Ah. Ten parallel cells give 2 mΩ and 50 Ah.", "formula": "R_parallel = R_cell/N; Q_parallel = N Q_cell; R_parallel Q_parallel = R_cell Q_cell", "note": "Only integer cell counts represent packs; lines show the scaling trend between them. Series resistance of busbars and joints is omitted.", "software": { "status": "reference", "label": "Reference concept", "body": "This is ideal electrical scaling, not a measured pack result. Real interconnects, mismatch, temperature and current sharing can break the simple scaling.", "href": "../fundamentals/capacity-and-c-rate/" }, "html": "
Resistance decreases with parallel count
Resistance decreases with parallel countIdentical cells in parallel versus Resistance (mΩ). Equivalent resistance. Interpretation follows the graphs.0155.751010.51515.32020Identical cells in parallelResistance (mΩ)
Equivalent resistance
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The capacity-normalized product
The capacity-normalized productIdentical cells in parallel versus Resistance × capacity (mΩ·Ah). R × Q. Interpretation follows the graphs.01305.756010.59015.312020Identical cells in parallelResistance × capacity(mΩ·Ah)
R × Q
" } } ] }