{
  "name": "Furnace battery drain JSON endpoint",
  "description": "Returns overnight RV furnace blower watt-hours, battery nights before stop-SOC, furnace propane use, propane nights before reserve, and the first winter-stay limiter.",
  "publisher": {
    "name": "OffGridRVHub",
    "url": "https://www.offgridrvhub.com"
  },
  "source": {
    "endpoint": "https://www.offgridrvhub.com/tools/api/furnace-battery-drain.json",
    "fullCalculator": "https://www.offgridrvhub.com/tools/furnace-battery-drain-calculator",
    "assumptions": "https://www.offgridrvhub.com/tools/calculator-assumptions",
    "documentation": "https://www.offgridrvhub.com/tools/calculator-api"
  },
  "caveat": "This is a planning estimate for RV education and comparison. It is not electrical, plumbing, safety, or installation advice.",
  "input": {
    "furnaceBtuPerHour": 30000,
    "furnaceDutyCyclePercent": 35,
    "heatingHoursPerNight": 10,
    "blowerWatts": 95,
    "nights": 4,
    "batteryAh": 200,
    "batteryVoltage": 12,
    "batteryType": "lithium",
    "startingSocPercent": 100,
    "minimumSocPercent": 20,
    "otherNightlyWh": 450,
    "propaneCapacityPounds": 40,
    "propaneReservePercent": 15
  },
  "result": {
    "nightlyBlowerWh": 333,
    "nightlyOtherWh": 450,
    "nightlyTotalWh": 783,
    "tripTotalWh": 3132,
    "nightlyBatteryAh": 65.3,
    "usableBatteryWh": 1920,
    "batteryUsePercentPerNight": 41,
    "batteryNightsBeforeFloor": 2.5,
    "furnaceBtuPerNight": 105000,
    "propanePoundsPerNight": 4.86,
    "usablePropanePounds": 34,
    "propaneNightsBeforeReserve": 7,
    "firstLimiter": "battery",
    "requiredBatteryAhForTrip": 350,
    "recommendedBatteryAhForTrip": 400,
    "verdictTitle": "Battery is likely the winter-stay limiter",
    "verdictDetail": "The furnace blower and overnight loads use about 783Wh per night, or 65.3Ah at 12V. Battery reserve lasts roughly 2.5 nights, while furnace propane lasts roughly 7 nights before reserve.",
    "recommendedNextMove": "Add usable battery capacity, lower overnight loads, raise the stop-SOC only if chemistry allows, or plan generator/alternator recharge between cold nights.",
    "watchOuts": [
      "Furnace blower watts vary by furnace model, duct restriction, battery voltage, fan condition, and how clean the return-air path is.",
      "Duty cycle changes quickly with outside temperature, wind, insulation, slide-outs, thermostat setting, and how often doors open.",
      "Low battery voltage can make furnace boards and fans misbehave before the bank looks fully empty on a simple capacity estimate.",
      "The propane estimate covers furnace heat only. Add fridge, water heater, cooking, and generator propane use with the propane runtime calculator if those loads matter."
    ]
  }
}