{ "node": { "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" ] } }, "edges": [ { "id": "edge:128", "source": "term:dcir", "target": "workflow:hppc", "type": "usedIn", "properties": { "sourceFile": "wiki-blocks.json" } }, { "id": "edge:2646", "source": "term:dcir", "target": "topic:topic-testing", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:2647", "source": "term:dcir", "target": "term:internal-resistance", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:2648", "source": "term:dcir", "target": "term:acir", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:2649", "source": "term:dcir", "target": "term:hppc", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:2650", "source": "term:dcir", "target": "term:impedance-rise", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:mentions/dcir/state-of-charge", "source": "term:dcir", "target": "term:state-of-charge", "type": "mentions", "properties": { "sourceFile": "terms.json", "method": "build_glossary.mention_index + mentions", "field": "definition", "meaning": "Text mention; not a causal claim" } }, { "id": "edge:mentions/dcir/diffusion", "source": "term:dcir", "target": "term:diffusion", "type": "mentions", "properties": { "sourceFile": "terms.json", "method": "build_glossary.mention_index + mentions", "field": "definition", "meaning": "Text mention; not a causal claim" } }, { "id": "edge:2653", "source": "term:dcir", "target": "visual:voltage", "type": "illustratedBy", "properties": { "sourceFile": "visual-pages.json" } }, { "id": "edge:2654", "source": "term:dcir", "target": "reference:inl-ev-tests", "type": "cites", "properties": { "sourceFile": "wiki-references.json", "scope": "direct technical reference" } } ], "neighbors": [ { "id": "workflow:hppc", "type": "Workflow", "label": "Inspect pulse characterization", "properties": { "id": "hppc", "title": "Inspect pulse characterization", "kind": "protocol", "summary": "HPPC alternates pulses, moves SOC and includes long rests.", "steps": [ "Open HPPC pulse characterization.", "Compare immediate voltage change and recovery." ], "example": "0.2 V change after a 10 A step gives 20 mΩ by ΔV/ΔI on the same cell/pack basis.", "observe": "Long rests differ from the immediate resistive jump.", "limits": "The estimate depends on timing, temperature and state; this is not AC impedance spectroscopy.", "url": "https://design.lemonergy.com/", "label": "Open Design → Protocol bench", "evidence": [ "js/test-protocol.js" ] } }, { "id": "topic:topic-testing", "type": "Topic", "label": "Testing methods", "properties": { "id": "topic-testing", "name": "Testing methods", "lede": "The measurements and test procedures that characterise a cell or pack, from capacity and pulse tests to abuse and environmental tests.", "context": "Record specimen, state, instrument, temperature and timing.", "example": "Resistance immediately after a current step can differ from a ten-second value because slower polarization contributes.", "lesson_url": "https://lemonergy.com/learn/fundamentals/capacity-and-c-rate/", "lesson_label": "Open capacity measurements" } }, { "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:acir", "type": "Term", "label": "AC internal resistance", "properties": { "id": "acir", "name": "AC internal resistance", "abbr": "ACIR", "aka": [ "1 kHz impedance" ], "section": "topic-testing", "definition": "The magnitude of a cell’s impedance at one fixed frequency, usually 1 kHz, measured in a second with a small alternating signal. It captures mostly the ohmic resistance, so it is quick for production sorting but blind to interfaces and diffusion.", "unit": "mΩ", "related": [ "dcir", "internal-resistance", "electrochemical-impedance-spectroscopy", "end-of-line-testing" ], "url": "https://lemonergy.com/learn/glossary/acir/", "mentions": [ "impedance", "diffusion" ] } }, { "id": "term:hppc", "type": "Term", "label": "Hybrid pulse power characterisation", "properties": { "id": "hppc", "name": "Hybrid pulse power characterisation", "abbr": "HPPC", "section": "topic-testing", "definition": "A test that applies a short discharge pulse and a short charge pulse at each state of charge, from which resistance and power capability are read as a function of SOC. It is the standard source of equivalent-circuit parameters.", "related": [ "equivalent-circuit-model", "state-of-power", "internal-resistance", "dcir", "pulse-test" ], "url": "https://lemonergy.com/learn/glossary/hppc/", "mentions": [ "state-of-charge" ] } }, { "id": "term:impedance-rise", "type": "Term", "label": "Impedance rise", "properties": { "id": "impedance-rise", "name": "Impedance rise", "aka": [ "resistance growth", "power fade" ], "section": "topic-aging", "definition": "An increase in a cell’s internal resistance as it ages. It costs voltage under load and therefore power, even while the stored charge is still there.", "related": [ "internal-resistance", "sei", "cei", "state-of-power", "state-of-health" ], "lesson": "fundamentals/battery-aging/#crystals", "url": "https://lemonergy.com/learn/glossary/impedance-rise/", "mentions": [ "closed-circuit-voltage" ] } }, { "id": "term:state-of-charge", "type": "Term", "label": "State of charge", "properties": { "id": "state-of-charge", "name": "State of charge", "abbr": "SOC", "section": "topic-state", "definition": "How full a cell is, as a fraction of its available capacity. State of charge, like temperature, affects how fast a stored cell ages.", "unit": "%", "related": [ "depth-of-discharge", "ocv-soc-curve", "coulomb-counting", "state-of-health", "bms" ], "lesson": "fundamentals/battery-aging/#storage-soc", "example": { "title": "Interpret a charge inventory", "text": "If available capacity is 5 Ah and 3 Ah remains by the chosen estimator, SOC is 60%. A different estimate of available capacity changes this percentage, so compare SOC values only with the capacity convention recorded." }, "url": "https://lemonergy.com/learn/glossary/state-of-charge/", "mentions": [ "usable-capacity" ] } }, { "id": "term:diffusion", "type": "Term", "label": "Diffusion", "properties": { "id": "diffusion", "name": "Diffusion", "section": "topic-transport", "definition": "The net movement of a species from where it is concentrated to where it is scarce, driven by random thermal motion. In a cell lithium diffuses through the electrolyte in the pores and, far more slowly, through the solid particles themselves.", "related": [ "ficks-first-law", "diffusion-coefficient", "solid-state-diffusion", "concentration-gradient", "migration" ], "lesson": "transport/ficks-first-law/#in-a-cell", "url": "https://lemonergy.com/learn/glossary/diffusion/", "mentions": [ "electrolyte" ] } }, { "id": "visual:voltage", "type": "Visual", "label": "Voltage under load", "properties": { "title": "Voltage under load", "summary": "Discharge current creates an ohmic drop below open-circuit voltage.", "readout": "5 A through 20 mΩ gives 0.1 V ohmic drop.", "formula": "V_terminal = OCV − I_discharge R", "note": "Chosen OCV curve; no chemistry calibration, hysteresis or voltage cutoff.", "software": { "status": "studio", "label": "Voltage relationship in Studio", "body": "The native battery calculates terminal voltage from OCV and resistance. The curve here is an illustrative OCV relationship, not a fitted cell dataset.", "href": "https://design.lemonergy.com/cosim.html?example=charging-home" }, "html": "
Illustrative OCV and loaded voltage
Illustrative OCV and loaded voltageSOC (%) versus Voltage (V). Open circuit; Under load. Interpretation follows the graphs.1.802.42253.05503.67754.3100SOC (%)Voltage (V)
Open circuitUnder load (dashed)
" } }, { "id": "reference:inl-ev-tests", "type": "Reference", "label": "Battery Test Manual For Electric Vehicles, Revision 3", "properties": { "title": "Battery Test Manual For Electric Vehicles, Revision 3", "publisher": "Idaho National Laboratory", "url": "https://inldigitallibrary.inl.gov/sites/sti/sti/6492291.pdf", "type": "Test manual", "scope": "Performance characterization, pulse resistance/power, life testing and reference performance tests; historical 2015 edition.", "year": 2015, "authors": [ "Jon P. Christopherson" ], "accessed": "2026-10-27" } } ] }