{
"node": {
"id": "term:pre-charge",
"type": "Term",
"label": "Pre-charge circuit",
"properties": {
"id": "pre-charge",
"name": "Pre-charge circuit",
"section": "topic-hvsafety",
"definition": "A resistor and small contactor that charge the inverter’s capacitors slowly before the main contactor closes. Without it the inrush into empty capacitors can reach thousands of amperes and weld the main contactor shut.",
"related": [
"contactor",
"battery-disconnect-unit",
"inverter"
],
"url": "https://lemonergy.com/learn/glossary/pre-charge/",
"mentions": [
"inrush-current"
]
}
},
"edges": [
{
"id": "edge:2886",
"source": "term:pre-charge",
"target": "topic:topic-hvsafety",
"type": "belongsTo",
"properties": {
"sourceFile": "terms.json"
}
},
{
"id": "edge:2887",
"source": "term:pre-charge",
"target": "term:contactor",
"type": "relatedTo",
"properties": {
"sourceFile": "terms.json",
"meaning": "Related context; not a causal claim"
}
},
{
"id": "edge:2888",
"source": "term:pre-charge",
"target": "term:battery-disconnect-unit",
"type": "relatedTo",
"properties": {
"sourceFile": "terms.json",
"meaning": "Related context; not a causal claim"
}
},
{
"id": "edge:2889",
"source": "term:pre-charge",
"target": "term:inverter",
"type": "relatedTo",
"properties": {
"sourceFile": "terms.json",
"meaning": "Related context; not a causal claim"
}
},
{
"id": "edge:mentions/pre-charge/inrush-current",
"source": "term:pre-charge",
"target": "term:inrush-current",
"type": "mentions",
"properties": {
"sourceFile": "terms.json",
"method": "build_glossary.mention_index + mentions",
"field": "definition",
"meaning": "Text mention; not a causal claim"
}
},
{
"id": "edge:2891",
"source": "term:pre-charge",
"target": "visual:capacitor",
"type": "illustratedBy",
"properties": {
"sourceFile": "visual-pages.json"
}
}
],
"neighbors": [
{
"id": "topic:topic-hvsafety",
"type": "Topic",
"label": "High-voltage and functional safety",
"properties": {
"id": "topic-hvsafety",
"name": "High-voltage and functional safety",
"lede": "Keeping people safe from the pack’s voltage and keeping its electronics safe when they fail: insulation, switching, fusing and the functional-safety process.",
"context": "Relate protection to faults, detection and response.",
"example": "Normal-operation current limits do not demonstrate correct contactor behavior under a welded-contact or sensor fault.",
"lesson_url": "https://lemonergy.com/learn/fundamentals/battery-basics/",
"lesson_label": "Open battery basics"
}
},
{
"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: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:inverter",
"type": "Term",
"label": "Inverter",
"properties": {
"id": "inverter",
"name": "Inverter",
"aka": [
"power conversion system",
"PCS"
],
"section": "topic-pack",
"definition": "The power electronics that turn the battery’s DC into AC for a motor or the grid, and back again for charging. In stationary storage it is called the power conversion system and its rating in kW or MW sets the system’s power independently of the battery’s energy.",
"related": [
"pre-charge",
"dc-dc-converter",
"stationary-storage",
"energy-management-system",
"direct-current",
"iec-62477-1"
],
"url": "https://lemonergy.com/learn/glossary/inverter/",
"mentions": []
}
},
{
"id": "term:inrush-current",
"type": "Term",
"label": "Inrush current",
"properties": {
"id": "inrush-current",
"name": "Inrush current",
"aka": [
"inrush",
"surge current",
"switch-on surge"
],
"section": "topic-hvsafety",
"definition": "The brief current peak when a circuit is first energised, before its capacitors have charged or its magnetic parts have settled. Connected straight to a pack, an inverter’s empty DC-link capacitors would draw thousands of amperes, so a pre-charge circuit brings them to about 95% of pack voltage before the main contactor closes.",
"related": [
"pre-charge",
"contactor",
"inverter",
"blanking-delay",
"fuse-coordination"
],
"url": "https://lemonergy.com/learn/glossary/inrush-current/",
"mentions": [
"pack-voltage"
]
}
},
{
"id": "visual:capacitor",
"type": "Visual",
"label": "Capacitor charge and energy",
"properties": {
"title": "Capacitor charge and energy",
"summary": "Charge rises linearly with voltage; energy rises with voltage squared.",
"readout": "At 5 V: 25 C and 62.5 J.",
"formula": "Q = CV; E = ½CV²",
"note": "Ideal constant capacitance; leakage, series resistance and voltage rating excluded.",
"software": {
"status": "reference",
"label": "Reference concept",
"body": "Q = CV and E = ½CV² explain capacitor storage. The battery nominal-energy helper alone does not simulate capacitor precharge.",
"href": "../fundamentals/battery-basics/"
},
"html": "Stored charge