{
  "schemaVersion": 1,
  "slug": "ev-charging-cost-calculator",
  "category": "automotive",
  "kind": "implementation",
  "independentValidation": false,
  "implementationHash": "7d4d848f4150394c9481a2c31b93165a83c290771e80698bf373ba0f2267e4b6",
  "provenance": "Generated from the calculation contract used by the published page. Publication is not external validation.",
  "sourceFiles": [
    "data/calculators/ev-charging-cost-calculator.json",
    "src/engine.js"
  ],
  "runtimeSource": "/sources/engine.txt",
  "runtimeHash": "5c888d8898afbdee36267bb9977829e1e2ac568f6677c8ee87469c139864645c",
  "scope": "The compute function records implemented equations, constants, lookup tables and custom rules. Inputs record defaults and allowed values; outputs record precision and units. Defaults are examples, not recommendations. General background references are not evidence for this specific algorithm.",
  "publishedFormula": {
    "formula": "C = B × (p_t − p_s) ÷ 100 ÷ η_c × r + f; C_100mi = 100 ÷ e ÷ η_c × r",
    "vars": [
      [
        "B",
        "Battery capacity (kWh)"
      ],
      [
        "p_s",
        "Start charge (%)"
      ],
      [
        "p_t",
        "Target charge (%)"
      ],
      [
        "r",
        "Electricity rate (per kWh)"
      ],
      [
        "f",
        "Session fee"
      ],
      [
        "η_c",
        "Entered charging efficiency (fraction)"
      ],
      [
        "e",
        "Vehicle efficiency (mi/kWh)"
      ]
    ],
    "note": "Use η ÷ 100 to convert the entered efficiency to a fraction. Grid energy = stored battery energy ÷ η. Actual charging losses vary; use measured or vehicle-specific data when available. Cost per 100 mi excludes session fees."
  },
  "externalEvidence": null,
  "contract": {
    "compute": "const eff=chargingEfficiency/100; if(targetPercent<startPercent) return {energyStored:null,energyDrawn:null,costPerSession:null,monthlyCost:null,costPer100Miles:null,__error:'invalidChargeRange'}; const energyStored=batteryKwh*(targetPercent-startPercent)/100; const energyDrawn=energyStored/eff; const costPerSession=energyDrawn*rate+extraFee; return {energyStored,energyDrawn,costPerSession,monthlyCost:costPerSession*monthlyCharges,costPer100Miles:efficiency>0?100/efficiency/eff*rate:0};",
    "inputs": [
      {
        "name": "batteryKwh",
        "type": "number",
        "default": 75,
        "min": 5,
        "max": 500,
        "step": 1,
        "slider": true
      },
      {
        "name": "startPercent",
        "type": "number",
        "default": 20,
        "min": 0,
        "max": 100,
        "step": 1,
        "slider": true
      },
      {
        "name": "targetPercent",
        "type": "number",
        "default": 80,
        "min": 0,
        "max": 100,
        "step": 1,
        "slider": true
      },
      {
        "name": "rate",
        "type": "number",
        "default": 0.17,
        "min": 0,
        "max": 5,
        "step": 0.001,
        "slider": true
      },
      {
        "name": "chargingEfficiency",
        "type": "number",
        "default": 90,
        "min": 50,
        "max": 100,
        "step": 1,
        "slider": true
      },
      {
        "name": "monthlyCharges",
        "type": "number",
        "default": 8,
        "min": 0,
        "max": 100,
        "step": 1,
        "slider": true
      },
      {
        "name": "extraFee",
        "type": "number",
        "default": 0,
        "min": 0,
        "max": 100,
        "step": 0.5,
        "slider": true
      },
      {
        "name": "efficiency",
        "type": "number",
        "default": 3.3,
        "min": 0.5,
        "max": 10,
        "step": 0.1,
        "slider": true
      }
    ],
    "outputs": [
      {
        "name": "costPerSession",
        "precision": 2,
        "unit": "$"
      },
      {
        "name": "energyStored",
        "precision": 2,
        "unit": "kWh"
      },
      {
        "name": "energyDrawn",
        "precision": 2,
        "unit": "kWh"
      },
      {
        "name": "monthlyCost",
        "precision": 2,
        "unit": "$"
      },
      {
        "name": "costPer100Miles",
        "precision": 2,
        "unit": "$"
      }
    ],
    "interpret": null
  }
}