{
"node": {
"id": "term:pack-voltage",
"type": "Term",
"label": "Pack voltage",
"properties": {
"id": "pack-voltage",
"name": "Pack voltage",
"aka": [
"400 V system",
"800 V system"
],
"section": "topic-pack",
"definition": "The nominal voltage of the full series string, about 400 V in most electric cars and 800 V in newer ones. Doubling the voltage halves the current for the same power, so cables, connectors and losses shrink and charging can be faster.",
"unit": "V",
"related": [
"series-parallel",
"dc-fast-charging",
"high-voltage-interlock",
"insulation-resistance"
],
"url": "https://lemonergy.com/learn/glossary/pack-voltage/",
"mentions": [
"nominal-voltage",
"string"
]
}
},
"edges": [
{
"id": "edge:2825",
"source": "term:pack-voltage",
"target": "topic:topic-pack",
"type": "belongsTo",
"properties": {
"sourceFile": "terms.json"
}
},
{
"id": "edge:2826",
"source": "term:pack-voltage",
"target": "term:series-parallel",
"type": "relatedTo",
"properties": {
"sourceFile": "terms.json",
"meaning": "Related context; not a causal claim"
}
},
{
"id": "edge:2827",
"source": "term:pack-voltage",
"target": "term:dc-fast-charging",
"type": "relatedTo",
"properties": {
"sourceFile": "terms.json",
"meaning": "Related context; not a causal claim"
}
},
{
"id": "edge:2828",
"source": "term:pack-voltage",
"target": "term:high-voltage-interlock",
"type": "relatedTo",
"properties": {
"sourceFile": "terms.json",
"meaning": "Related context; not a causal claim"
}
},
{
"id": "edge:2829",
"source": "term:pack-voltage",
"target": "term:insulation-resistance",
"type": "relatedTo",
"properties": {
"sourceFile": "terms.json",
"meaning": "Related context; not a causal claim"
}
},
{
"id": "edge:mentions/pack-voltage/nominal-voltage",
"source": "term:pack-voltage",
"target": "term:nominal-voltage",
"type": "mentions",
"properties": {
"sourceFile": "terms.json",
"method": "build_glossary.mention_index + mentions",
"field": "definition",
"meaning": "Text mention; not a causal claim"
}
},
{
"id": "edge:mentions/pack-voltage/string",
"source": "term:pack-voltage",
"target": "term:string",
"type": "mentions",
"properties": {
"sourceFile": "terms.json",
"method": "build_glossary.mention_index + mentions",
"field": "definition",
"meaning": "Text mention; not a causal claim"
}
},
{
"id": "edge:2832",
"source": "term:pack-voltage",
"target": "visual:pack",
"type": "illustratedBy",
"properties": {
"sourceFile": "visual-pages.json"
}
}
],
"neighbors": [
{
"id": "topic:topic-pack",
"type": "Topic",
"label": "Modules, packs and battery management",
"properties": {
"id": "topic-pack",
"name": "Modules, packs and battery management",
"lede": "From a single cell to a working battery system, and the electronics that keep it safe.",
"context": "Make series/parallel architecture explicit.",
"example": "Twelve 3.6 V, 5 Ah cells in 6s2p give 21.6 V, 10 Ah and 216 Wh nominally before other restrictions.",
"lesson_url": "https://lemonergy.com/learn/fundamentals/cell-architecture/",
"lesson_label": "Open cell architecture"
}
},
{
"id": "term:series-parallel",
"type": "Term",
"label": "Series and parallel connection",
"properties": {
"id": "series-parallel",
"name": "Series and parallel connection",
"aka": [
"xSyP"
],
"section": "topic-pack",
"definition": "Cells in series add their voltages; cells in parallel add their capacities and share current. A pack is described as, for example, 96s4p: 96 groups in series, each of 4 cells in parallel. Series strings need balancing; parallel groups self-balance through their shared terminals.",
"formula": "V = n_s·V_cell, Q = n_p·Q_cell",
"related": [
"module",
"cell-balancing",
"pack-voltage",
"volt",
"fuse"
],
"lesson": "fundamentals/battery-basics/#cell-module-pack",
"example": {
"title": "Assemble an ideal 4s2p pack",
"text": "Eight identical 3.6 V, 5 Ah cells arranged as four series groups with two cells in parallel give 14.4 V nominal, 10 Ah and 144 Wh. Interconnect losses, cell variation and usable voltage limits are additional constraints."
},
"url": "https://lemonergy.com/learn/glossary/series-parallel/",
"mentions": []
}
},
{
"id": "term:dc-fast-charging",
"type": "Term",
"label": "DC fast charging",
"properties": {
"id": "dc-fast-charging",
"name": "DC fast charging",
"abbr": "DCFC",
"aka": [
"rapid charging",
"HPC"
],
"section": "topic-infrastructure",
"definition": "Charging from a station that supplies DC straight to the pack, bypassing the car’s onboard charger, at 50 kW to over 350 kW. The BMS, not the charger, sets the current from moment to moment, which is why the charge curve tapers as the pack fills.",
"related": [
"fast-charging",
"onboard-charger",
"pack-voltage",
"preconditioning",
"charging-curve",
"evse"
],
"url": "https://lemonergy.com/learn/glossary/dc-fast-charging/",
"mentions": [
"charger",
"bms"
]
}
},
{
"id": "term:high-voltage-interlock",
"type": "Term",
"label": "High-voltage interlock loop",
"properties": {
"id": "high-voltage-interlock",
"name": "High-voltage interlock loop",
"abbr": "HVIL",
"section": "topic-hvsafety",
"definition": "A low-voltage signal loop threaded through every high-voltage connector and cover. Opening any of them breaks the loop and the BMS drops the contactors, so a technician cannot reach a live conductor.",
"related": [
"contactor",
"pack-voltage",
"insulation-resistance",
"functional-safety"
],
"url": "https://lemonergy.com/learn/glossary/high-voltage-interlock/",
"mentions": [
"bms"
]
}
},
{
"id": "term:insulation-resistance",
"type": "Term",
"label": "Insulation resistance",
"properties": {
"id": "insulation-resistance",
"name": "Insulation resistance",
"aka": [
"isolation resistance",
"IMD"
],
"section": "topic-hvsafety",
"definition": "The resistance between the high-voltage circuit and the vehicle chassis, which must stay above about 100 Ω per volt of pack voltage so a person touching the chassis is safe. An insulation monitoring device measures it continuously.",
"unit": "Ω/V",
"related": [
"pack-voltage",
"high-voltage-interlock",
"functional-safety",
"insulation-test"
],
"url": "https://lemonergy.com/learn/glossary/insulation-resistance/",
"mentions": [
"volt"
]
}
},
{
"id": "term:nominal-voltage",
"type": "Term",
"label": "Nominal voltage",
"properties": {
"id": "nominal-voltage",
"name": "Nominal voltage",
"section": "topic-ratings",
"definition": "A representative average voltage of a cell over a full discharge, such as 3.6–3.7 V for an oxide/graphite cell or about 3.2 V for LFP/graphite. Multiplied by capacity, it gives nominal energy.",
"unit": "V",
"related": [
"nominal-energy",
"open-circuit-voltage",
"voltage-window",
"lfp"
],
"lesson": "fundamentals/capacity-and-c-rate/#energy",
"url": "https://lemonergy.com/learn/glossary/nominal-voltage/",
"mentions": [
"graphite"
]
}
},
{
"id": "term:string",
"type": "Term",
"label": "String",
"properties": {
"id": "string",
"name": "String",
"aka": [
"battery string",
"series string"
],
"section": "topic-pack",
"definition": "A chain of cells or modules connected in series to reach the system voltage, the basic electrical unit of a large battery. In stationary storage each rack is usually one string of about 1000–1500 V with its own contactors and BMS, and many strings are paralleled on a common DC bus.",
"related": [
"series-parallel",
"pack-voltage",
"stationary-storage",
"parallel-string-current-sharing",
"bms-architecture",
"contactor"
],
"url": "https://lemonergy.com/learn/glossary/string/",
"mentions": [
"bms"
]
}
},
{
"id": "visual:pack",
"type": "Visual",
"label": "Series voltage and parallel capacity",
"properties": {
"title": "Series voltage and parallel capacity",
"summary": "Count series and parallel connections separately.",
"readout": "4S2P: 8 cells, 14.8 V, 10 Ah, 148 Wh.",
"formula": "V_pack = Ns V_cell; Q_pack = Np Q_cell",
"note": "Identical 3.7 V, 5 Ah cells; ideal equal current sharing and no losses.",
"software": {
"status": "reference",
"label": "Reference concept",
"body": "Ideal pack ratings use V_pack = Ns V_cell and Q_pack = Np Q_cell. The core energy helper can multiply these ratings. Imbalance and current sharing require additional models.",
"href": "../fundamentals/capacity-and-c-rate/"
},
"html": "Voltage along one series string