{
  "node": {
    "id": "term:iu-charging-characteristics",
    "type": "Term",
    "label": "IU, IUoU and IUI charging",
    "properties": {
      "id": "iu-charging-characteristics",
      "name": "IU, IUoU and IUI charging",
      "aka": [
        "IUoU",
        "IUI",
        "IUIa",
        "three-stage charging",
        "W characteristic",
        "DIN 41772"
      ],
      "section": "topic-charging",
      "definition": "The letter code, set out in DIN 41772, for a charger’s profile: I for a constant-current stage, U for constant voltage and W for current that falls as voltage rises. IUoU charges lead–acid at constant current, then at a raised voltage, then at a lower float voltage; IUI ends with a small constant current that finishes flooded traction cells and stirs their acid by gassing.",
      "related": [
        "lead-acid",
        "cc-cv-charging",
        "trickle-charge",
        "equalization-charge",
        "flooded-lead-acid"
      ],
      "url": "https://lemonergy.com/learn/glossary/iu-charging-characteristics/",
      "mentions": [
        "constant-current",
        "constant-voltage",
        "charger",
        "gas-generation"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:belongsTo/term:iu-charging-characteristics/topic:topic-charging",
      "source": "term:iu-charging-characteristics",
      "target": "topic:topic-charging",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:relatedTo/term:iu-charging-characteristics/term:lead-acid",
      "source": "term:iu-charging-characteristics",
      "target": "term:lead-acid",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:iu-charging-characteristics/term:cc-cv-charging",
      "source": "term:iu-charging-characteristics",
      "target": "term:cc-cv-charging",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:iu-charging-characteristics/term:trickle-charge",
      "source": "term:iu-charging-characteristics",
      "target": "term:trickle-charge",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:iu-charging-characteristics/term:equalization-charge",
      "source": "term:iu-charging-characteristics",
      "target": "term:equalization-charge",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:relatedTo/term:iu-charging-characteristics/term:flooded-lead-acid",
      "source": "term:iu-charging-characteristics",
      "target": "term:flooded-lead-acid",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/iu-charging-characteristics/constant-current",
      "source": "term:iu-charging-characteristics",
      "target": "term:constant-current",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/iu-charging-characteristics/constant-voltage",
      "source": "term:iu-charging-characteristics",
      "target": "term:constant-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/iu-charging-characteristics/charger",
      "source": "term:iu-charging-characteristics",
      "target": "term:charger",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/iu-charging-characteristics/gas-generation",
      "source": "term:iu-charging-characteristics",
      "target": "term:gas-generation",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    }
  ],
  "neighbors": [
    {
      "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:lead-acid",
      "type": "Term",
      "label": "Lead–acid battery",
      "properties": {
        "id": "lead-acid",
        "name": "Lead–acid battery",
        "section": "topic-other-chemistries",
        "definition": "The oldest rechargeable chemistry, lead and lead dioxide electrodes in sulfuric acid, at 2 V per cell. Heavy and short-lived in deep cycling but cheap, recyclable and good at cold cranking, it still starts most cars and backs up most telecom sites.",
        "related": [
          "nominal-voltage",
          "recycling",
          "specific-energy"
        ],
        "lesson": "labs/battery-materials-lab/#bml-market",
        "url": "https://lemonergy.com/learn/glossary/lead-acid/",
        "mentions": []
      }
    },
    {
      "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:trickle-charge",
      "type": "Term",
      "label": "Trickle and float charging",
      "properties": {
        "id": "trickle-charge",
        "name": "Trickle and float charging",
        "aka": [
          "float charge",
          "float charging",
          "trickle charge"
        ],
        "section": "topic-charging",
        "definition": "Holding a battery at a small current, or a fixed voltage, to keep it full. It is standard for lead–acid and NiMH but harmful for lithium-ion, which should be left to rest once charged; lithium-ion chargers instead top up when the voltage sags.",
        "related": [
          "lead-acid",
          "overcharge",
          "calendar-aging",
          "slow-charging",
          "oxygen-recombination"
        ],
        "url": "https://lemonergy.com/learn/glossary/trickle-charge/",
        "mentions": [
          "nickel-metal-hydride"
        ]
      }
    },
    {
      "id": "term:equalization-charge",
      "type": "Term",
      "label": "Equalization charge",
      "properties": {
        "id": "equalization-charge",
        "name": "Equalization charge",
        "section": "topic-charging",
        "definition": "A deliberate, controlled overcharge of a lead–acid battery that brings weaker cells up to full and stirs the electrolyte. It must never be applied to lithium-ion cells, which are equalised electronically by the BMS instead.",
        "related": [
          "lead-acid",
          "cell-balancing",
          "overcharge",
          "trickle-charge"
        ],
        "url": "https://lemonergy.com/learn/glossary/equalization-charge/",
        "mentions": [
          "electrolyte",
          "bms"
        ]
      }
    },
    {
      "id": "term:flooded-lead-acid",
      "type": "Term",
      "label": "Flooded lead–acid",
      "properties": {
        "id": "flooded-lead-acid",
        "name": "Flooded lead–acid",
        "aka": [
          "vented lead–acid",
          "wet cell"
        ],
        "section": "topic-other-chemistries",
        "definition": "The traditional lead–acid construction with free liquid electrolyte, vents and removable caps for topping up with water. It is cheap and tolerant of overcharge but must stay upright and be maintained.",
        "related": [
          "lead-acid",
          "vrla",
          "equalization-charge",
          "sulfation"
        ],
        "url": "https://lemonergy.com/learn/glossary/flooded-lead-acid/",
        "mentions": [
          "electrolyte",
          "overcharge"
        ]
      }
    },
    {
      "id": "term:constant-current",
      "type": "Term",
      "label": "Constant current",
      "properties": {
        "id": "constant-current",
        "name": "Constant current",
        "abbr": "CC",
        "section": "topic-charging",
        "definition": "A charge or discharge at a fixed current, so capacity is simply current times time. It is the first stage of a CC-CV charge and the normal way to run a capacity test.",
        "related": [
          "cc-cv-charging",
          "constant-voltage",
          "c-rate",
          "capacity-test"
        ],
        "example": {
          "title": "Compare two cell capacities",
          "text": "A 2 A current is 1C for a 2 Ah cell and 0.4C for a 5 Ah cell. A constant-current step holds amperes fixed, so a fair comparison between differently sized cells also records C-rate."
        },
        "url": "https://lemonergy.com/learn/glossary/constant-current/",
        "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: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": "term:gas-generation",
      "type": "Term",
      "label": "Gas generation",
      "properties": {
        "id": "gas-generation",
        "name": "Gas generation",
        "aka": [
          "gassing"
        ],
        "section": "topic-aging",
        "definition": "Formation of gases — ethylene, hydrogen, carbon monoxide and carbon dioxide — by electrolyte decomposition, mostly during formation and later under high voltage or temperature. In a pouch cell it shows as swelling; in a can it raises pressure until the vent opens.",
        "related": [
          "swelling",
          "degassing",
          "electrolyte-decomposition",
          "vent",
          "formation"
        ],
        "lesson": "fundamentals/battery-aging/#gas",
        "url": "https://lemonergy.com/learn/glossary/gas-generation/",
        "mentions": [
          "electrolyte",
          "pouch-cell"
        ]
      }
    }
  ]
}