{ "node": { "id": "term:cp-cv", "type": "Term", "label": "Constant-power charging", "properties": { "id": "cp-cv", "name": "Constant-power charging", "abbr": "CP-CV", "section": "topic-charging", "definition": "Charging with a fixed-power stage, so current falls as voltage rises because current equals power divided by voltage. In a CP-CV protocol, a constant-voltage stage follows when the voltage limit is reached. A power rating alone does not establish that a charger implements this sequence.", "related": [ "cc-cv-charging", "constant-voltage", "e-rate", "charger" ], "example": { "title": "See why current falls at constant power", "text": "An illustrative 20 W constant-power stage requires 5 A at 4 V and 4 A at 5 V. At the chosen voltage ceiling, the profile changes to CV and power tapers with current." }, "notes": [ "This arithmetic illustrates P = VI; these voltages are not recommendations for a lithium-ion cell." ], "url": "https://lemonergy.com/learn/glossary/cp-cv/", "mentions": [] } }, "edges": [ { "id": "edge:123", "source": "term:cp-cv", "target": "workflow:constant-power", "type": "usedIn", "properties": { "sourceFile": "wiki-blocks.json" } }, { "id": "edge:4466", "source": "term:cp-cv", "target": "topic:topic-charging", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:4467", "source": "term:cp-cv", "target": "term:cc-cv-charging", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:4468", "source": "term:cp-cv", "target": "term:constant-voltage", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:4469", "source": "term:cp-cv", "target": "term:e-rate", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:4470", "source": "term:cp-cv", "target": "term:charger", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:4471", "source": "term:cp-cv", "target": "visual:charging-cp", "type": "illustratedBy", "properties": { "sourceFile": "visual-pages.json" } }, { "id": "edge:4472", "source": "term:cp-cv", "target": "reference:tomaszewska-charging", "type": "cites", "properties": { "sourceFile": "wiki-references.json", "scope": "direct technical reference" } } ], "neighbors": [ { "id": "workflow:constant-power", "type": "Workflow", "label": "Program constant power", "properties": { "id": "constant-power", "title": "Program constant power", "kind": "protocol", "summary": "Positive power magnitude and explicit direction define CP.", "steps": [ "Select CP and duration.", "Inspect current as voltage changes." ], "example": "2 kW at 100 V implies 20 A; at 120 V it implies about 16.7 A.", "observe": "Current follows I = P/V.", "limits": "This is CP only, not a combined CP–CV controller. CC and CP cannot share a protocol.", "url": "https://design.lemonergy.com/", "label": "Open Design → Protocol bench", "evidence": [ "js/test-protocol.js" ] } }, { "id": "topic:topic-charging", "type": "Topic", "label": "Charging and discharging", "properties": { "id": "topic-charging", "name": "Charging and discharging", "lede": "How current goes in and comes out, and the limits that stop it.", "context": "Separate regulation from availability.", "example": "The same CC–CV law can operate overnight or during a short depot stop.", "lesson_url": "https://lemonergy.com/learn/fundamentals/capacity-and-c-rate/", "lesson_label": "Open charging quantities" } }, { "id": "term:cc-cv-charging", "type": "Term", "label": "CC-CV charging", "properties": { "id": "cc-cv-charging", "name": "CC-CV charging", "aka": [ "constant current constant voltage" ], "section": "topic-charging", "definition": "The standard lithium-ion charge protocol: constant current until the cell reaches its upper cutoff voltage, then that voltage held constant while the current tapers. The charge ends when the current falls to a set fraction, often C/20.", "related": [ "constant-current", "constant-voltage", "cutoff-voltage", "taper-current", "fast-charging", "cp-cv" ], "lesson": "fundamentals/capacity-and-c-rate/#real-cells", "example": { "title": "Follow a two-stage charge", "text": "For an illustrative 5 Ah cell, a 2.5 A current request is 0.5C. During CC the voltage rises. At the selected upper voltage, CV regulation holds voltage while current tapers. Completion requires the taper current to fall below the selected cutoff for the configured dwell." }, "notes": [ "Choose voltage, current and temperature limits from the actual cell specification. These example values do not define a charging recipe." ], "url": "https://lemonergy.com/learn/glossary/cc-cv-charging/", "mentions": [] } }, { "id": "term:constant-voltage", "type": "Term", "label": "Constant voltage", "properties": { "id": "constant-voltage", "name": "Constant voltage", "abbr": "CV", "section": "topic-charging", "definition": "A charge stage in which the terminal voltage is held at a selected limit while the current is allowed to fall. The charge added during this stage and its duration depend on the cell, initial state, voltage limit and termination current.", "related": [ "cc-cv-charging", "constant-current", "taper-current", "cutoff-voltage" ], "example": { "title": "Read the taper correctly", "text": "In a hypothetical CV stage with a 4.0 V ceiling, the controller holds terminal voltage at that ceiling while current tapers as the cell state changes and its OCV rises. A voltage plateau does not mean the charge session has completed; the current cutoff and dwell still matter." }, "url": "https://lemonergy.com/learn/glossary/constant-voltage/", "mentions": [ "voltage" ] } }, { "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": [] } }, { "id": "term:charger", "type": "Term", "label": "Charger", "properties": { "id": "charger", "name": "Charger", "section": "topic-charging", "definition": "The power electronics that convert mains or DC supply into the controlled current and voltage a battery needs. For lithium-ion it runs the CC-CV profile within the limits the BMS communicates, and stops rather than floats when the cell is full.", "related": [ "cc-cv-charging", "bms", "onboard-charger", "dc-fast-charging" ], "url": "https://lemonergy.com/learn/glossary/charger/", "mentions": [] } }, { "id": "visual:charging-cp", "type": "Visual", "label": "Compare charging profiles", "properties": { "title": "Compare charging profiles", "summary": "See which quantity is held constant, when the phase changes and how charging ends.", "readout": "Power holds at 16.25 W during CP. Current falls as voltage rises (I = P/V). At the example 4.15 V threshold, CV begins: voltage stays fixed while current and power taper.", "formula": "P = VI; I = P/V", "note": "Positive current charges the cell. Time is normalized; selected thresholds are not cell-specific recommendations. The voltage trace ends at termination; post-stop relaxation is excluded.", "software": { "status": "studio", "label": "Test protocol in Lemonergy", "body": "Sim → Open the protocol bench supports constant-power blocks. A CP block does not automatically become a CP-CV session. The combined CP-to-CV profile shown here is a reference illustration.", "href": "https://design.lemonergy.com/" }, "html": "
Current profile
Current profileRelative elapsed time versus Current (A). Charge current. Interpretation follows the graphs.CPCVStop001.440.252.880.54.310.755.751Relative elapsed timeCurrent (A)
Charge current
\n
Voltage profile
Voltage profileRelative elapsed time versus Cell voltage (V). Cell voltage. Interpretation follows the graphs.CPCVStop303.350.253.70.54.050.754.41Relative elapsed timeCell voltage (V)
Cell voltage
\n
Power: constant phase, then taper
Power: constant phase, then taperRelative elapsed time versus Power (W). Charge power. Interpretation follows the graphs.CPCVStop0050.25100.5150.75201Relative elapsed timePower (W)
Charge power
" } }, { "id": "reference:tomaszewska-charging", "type": "Reference", "label": "Lithium-ion battery fast charging: A review", "properties": { "title": "Lithium-ion battery fast charging: A review", "publisher": "eTransportation", "url": "https://doi.org/10.1016/j.etran.2019.100011", "type": "Review article", "scope": "CC-CV and alternative charging protocols, transport limitations, degradation and thermal implications; results depend on cell and test conditions. Software behavior is documented separately in Lemonergy block references.", "year": 2019, "authors": [ "Anna Tomaszewska et al." ], "accessed": "2026-10-27" } } ] }