{
"node": {
"id": "term:split-pack",
"type": "Term",
"label": "Split pack",
"properties": {
"id": "split-pack",
"name": "Split pack",
"aka": [
"switchable pack",
"reconfigurable pack",
"400/800 V switching"
],
"section": "topic-pack",
"definition": "A pack built as two halves that contactors can connect in series or in parallel, so the same battery works at two voltages. GM’s Hummer EV drives at 400 V with its halves in parallel and switches them to series for 800 V fast charging; other designs split an 800 V pack to use 400 V chargers.",
"related": [
"pack-voltage",
"contactor",
"series-parallel",
"dc-fast-charging",
"battery-disconnect-unit",
"split-pack-charging"
],
"url": "https://lemonergy.com/learn/glossary/split-pack/",
"mentions": [
"fast-charging"
]
}
},
"edges": [
{
"id": "edge:4931",
"source": "term:split-pack",
"target": "topic:topic-pack",
"type": "belongsTo",
"properties": {
"sourceFile": "terms.json"
}
},
{
"id": "edge:4932",
"source": "term:split-pack",
"target": "term:pack-voltage",
"type": "relatedTo",
"properties": {
"sourceFile": "terms.json",
"meaning": "Related context; not a causal claim"
}
},
{
"id": "edge:4933",
"source": "term:split-pack",
"target": "term:contactor",
"type": "relatedTo",
"properties": {
"sourceFile": "terms.json",
"meaning": "Related context; not a causal claim"
}
},
{
"id": "edge:4934",
"source": "term:split-pack",
"target": "term:series-parallel",
"type": "relatedTo",
"properties": {
"sourceFile": "terms.json",
"meaning": "Related context; not a causal claim"
}
},
{
"id": "edge:4935",
"source": "term:split-pack",
"target": "term:dc-fast-charging",
"type": "relatedTo",
"properties": {
"sourceFile": "terms.json",
"meaning": "Related context; not a causal claim"
}
},
{
"id": "edge:4936",
"source": "term:split-pack",
"target": "term:battery-disconnect-unit",
"type": "relatedTo",
"properties": {
"sourceFile": "terms.json",
"meaning": "Related context; not a causal claim"
}
},
{
"id": "edge:4937",
"source": "term:split-pack",
"target": "term:split-pack-charging",
"type": "relatedTo",
"properties": {
"sourceFile": "terms.json",
"meaning": "Related context; not a causal claim"
}
},
{
"id": "edge:mentions/split-pack/fast-charging",
"source": "term:split-pack",
"target": "term:fast-charging",
"type": "mentions",
"properties": {
"sourceFile": "terms.json",
"method": "build_glossary.mention_index + mentions",
"field": "definition",
"meaning": "Text mention; not a causal claim"
}
},
{
"id": "edge:4939",
"source": "term:split-pack",
"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: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"
]
}
},
{
"id": "term:contactor",
"type": "Term",
"label": "Contactor",
"properties": {
"id": "contactor",
"name": "Contactor",
"section": "topic-hvsafety",
"definition": "A heavy-duty electrically operated switch that connects the pack to the vehicle or inverter and opens it on fault or shutdown. Packs use at least two, one per pole, plus a pre-charge path to avoid welding them on the first connection.",
"related": [
"pre-charge",
"battery-disconnect-unit",
"pyrofuse",
"bms"
],
"url": "https://lemonergy.com/learn/glossary/contactor/",
"mentions": [
"inverter"
]
}
},
{
"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:battery-disconnect-unit",
"type": "Term",
"label": "Battery disconnect unit",
"properties": {
"id": "battery-disconnect-unit",
"name": "Battery disconnect unit",
"abbr": "BDU",
"aka": [
"battery junction box"
],
"section": "topic-hvsafety",
"definition": "The box inside the pack that holds the contactors, pre-charge circuit, main fuse or pyrofuse and current sensor, where the pack’s high-voltage connections are made and broken.",
"related": [
"contactor",
"pre-charge",
"fuse",
"pyrofuse",
"current-sensor"
],
"url": "https://lemonergy.com/learn/glossary/battery-disconnect-unit/",
"mentions": []
}
},
{
"id": "term:split-pack-charging",
"type": "Term",
"label": "Split-pack charging",
"properties": {
"id": "split-pack-charging",
"name": "Split-pack charging",
"aka": [
"bank charging",
"pack splitting",
"series–parallel switching"
],
"section": "topic-charging",
"definition": "Reconfiguring a pack with contactors so that its two halves charge in parallel at half the drive voltage. An 800 V vehicle such as the Tesla Cybertruck can then use 400 V fast chargers without a DC/DC booster; GM’s Hummer EV does the reverse, driving at 400 V and switching the halves into series to charge at 800 V.",
"related": [
"pack-voltage",
"contactor",
"dc-fast-charging",
"series-parallel",
"dc-dc-converter",
"hpc"
],
"url": "https://lemonergy.com/learn/glossary/split-pack-charging/",
"mentions": []
}
},
{
"id": "term:fast-charging",
"type": "Term",
"label": "Fast charging",
"properties": {
"id": "fast-charging",
"name": "Fast charging",
"section": "topic-charging",
"definition": "Charging intended to replenish a specified amount of energy or state of charge in a short time. There is no universal C-rate threshold: performance depends on cell chemistry, temperature, starting state and power limits. High current can increase heating and lithium-plating risk, requiring appropriate limits.",
"related": [
"lithium-plating",
"c-rate",
"cc-cv-charging",
"dc-fast-charging",
"thermal-management",
"mscc"
],
"url": "https://lemonergy.com/learn/glossary/fast-charging/",
"mentions": [
"state-of-charge"
]
}
},
{
"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