Power Station Battery Runtime Calculator
A 1000 Wh pack at 0.85 efficiency estimates to 12.1 hours on EIA’s 70 W most-used refrigerator average: 1000 × 0.85 ÷ 70 ≈ 12.1 hours. That assumes the inverter can start and run the fridge; we have not tested this combination.
Runtime (hours) ≈ battery capacity (Wh) × inverter efficiency ÷ load (W)
Default efficiency is 0.85, a planning assumption used on this site when a maker does not publish one. These are estimates from published inputs, not a lab test.
Estimate hours from your battery and load
Use the published battery capacity and average load for an AC-outlet estimate. This does not check startup, voltage, or continuous inverter limits.
Your runtime estimate
Check capacity and load: both must be finite numbers greater than zero. Efficiency must be between 0.1 and 1. The calculated result must be finite.
- Estimated runtime
- Enable JavaScript
- Capacity for target duration
- Optional stricter illustration
Target hours must be a finite number greater than zero and produce a finite capacity.
For the optional check, DoD and η must be greater than zero and no more than 1. Self-consumption must be zero or more. All inputs and results must be finite.
This is compressor-on or running watts, not a cycling average, so these hours are a shorter bound if the appliance cycles off. The estimate assumes the listed draw continues.
CPAP estimate: not medical advice or a UPS rating. Use your own manual and plan backup with your clinician.
Estimates only, not a lab test. Temperature, battery age, inverter overhead, and actual load change the hours. Enough stored energy does not prove that the inverter can start or power the appliance.
Inputs stay in this page’s URL, not an account. Copying a link shares the numbers and selected presets. Do not include private or medical details.
The same 70 W load, three calculations
The 1000 Wh capacity is a worked example, not a measured usable-energy figure. The 70 W preset rounds EIA’s 617 kWh/year: 617 ÷ 8,760 × 1,000 ≈ 70 W.
- Estimated runtime: 1000 × 0.85 ÷ 70 ≈ 12.1 hours.
- Capacity needed for a target duration: Wh ≈ hours × load W ÷ 0.85. For eight hours: 8 × 70 ÷ 0.85 ≈ 659 Wh. The calculator uses your edited efficiency if you change it and rounds required capacity up to a whole Wh.
- Optional stricter illustration: 1000 × 0.90 × 0.85 ÷ (70 + 15) ≈ 9.0 hours.
The stricter line uses BLUETTI’s published AC180 form: hours = Wh × DoD × η ÷ (load + self-consumption), with default DoD 0.90, η 0.85, and a 15 W planning allowance. The 15 W is not a measured standby figure for your pack. BLUETTI excludes inductive compressor loads such as refrigerators, so this fridge line illustrates arithmetic only. Prefer the maker’s formula when it covers the load.
The 1000 Wh outage guide works through the AC180 form, and the CPAP guide shows how overhead changes an overnight energy budget.
Average watts set hours; starting watts check the inverter
A compressor’s running watts apply while it is on. Its starting watts are a brief higher demand. Neither is automatically the cycling average that sets runtime. Use the generator and power station wattage calculator for the separate running and startup checks, and the refrigerator guide for the difference between these wattages.
Cycling loads need annual kWh or an energy meter over a useful period to get a useful average. Convert annual energy with average W ≈ annual kWh ÷ 8,760 × 1,000. Annual kWh already include cycling under the rating conditions; do not divide by a second guessed duty cycle. Heat, defrost, and door openings can change the actual outage load.
The 0.85 factor is an assumption, not an efficiency measurement for every station. Low loads can spend a larger share of energy on inverter overhead. Cold, aging, and reserved battery capacity also reduce available energy. A DC or USB path has different losses from the AC inverter modeled here.
Do not backfeed a wall outlet
Plug appliances into the station’s rated outlets. Do not feed building wiring through a wall receptacle. CPSC’s Portable Generator Hazards warns that backfeeding can electrocute utility workers and neighbors and bypass household protection. A battery inverter does not make that connection safe.
Any connection to building wiring needs an approved transfer arrangement and a qualified electrician. See backup power for renters and apartments for connection limits. CPAP estimates are not medical advice or a UPS rating; plan backup with your clinician and equipment provider.
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Sources for presets and limits
- EIA 2020 RECS Table CE5.3b, revised March 2024. Installed-base refrigerator and separate-freezer annual energy.
- ENERGY STAR Certified Residential Refrigerators dataset. The top-freezer median used in the refrigerator guide’s November 10, 2026 query.
- ENERGY STAR Certified Residential Freezers dataset. Chest and upright medians from the freezer guide’s November 11, 2026 query.
- ResMed AirSense 11 Americas user guide. Published typical and peak power, not a promise about your overnight settings.
- Honda wattage estimation guide and tailgating wattage notes. Running-watt presets, not cycling averages.
- BLUETTI AC180. Published runtime form, DoD and inverter efficiency, self-consumption allowance, and compressor exclusion.
- CPSC Portable Generator Hazards, Publication 5123. Backfeeding warning.
The load picker shows the source note for each preset. Optional station rows cite their published capacities, not our measurements. The LED preset is a label example, not a tested lamp.
Apply the estimate to your load
- Refrigerator runtime: average energy versus compressor starts.
- Chest-freezer runtime: low loads and inverter overhead.
- CPAP overnight planning: published watts and medical backup limits.
- What a 1000 Wh station can run during an outage: energy and output limits.
- Window AC and space-heater runtime: minutes under a high sustained load.
- Solar recharge planning: replenishing energy after the battery drains.
- Generator and power station wattage calculator: running and starting demand.
Frequently asked questions
How long will a 1000 Wh battery run a refrigerator?
At EIA’s 70 W most-used refrigerator average and an assumed 0.85 conversion factor, 1000 × 0.85 ÷ 70 ≈ 12.1 hours. That is an energy estimate, not a test of your fridge. The inverter must also handle compressor starts. Use your EnergyGuide annual kWh or an energy-meter average instead of the preset when you have it.
How many watt-hours do I need for eight hours?
At a 70 W average load and the default 0.85 efficiency, required Wh ≈ 8 × 70 ÷ 0.85 ≈ 659 Wh. This is a first energy budget, not a purchase recommendation. Leave margin for battery age, temperature, inverter overhead, and a higher actual load. Changing the efficiency input changes the required capacity.
Why is the optional stricter runtime shorter?
BLUETTI’s published AC180 form includes depth of discharge and the station’s own consumption: hours = Wh × DoD × η ÷ (load + self-consumption). At the default illustration, 1000 × 0.90 × 0.85 ÷ (70 + 15) = 9.0 hours. The 15 W is a planning allowance, not a measured standby figure for your pack. BLUETTI excludes inductive compressor loads such as refrigerators from this formula. Prefer your maker’s formula when it covers your load.