fridge runtime calculator
Fridge Runtime Calculator
Fridges are tricky because compressor surge and cycling matter more than the simple label wattage.
Calculator
Start with a quick estimate, then switch to Advanced if you need multiple devices, startup surge, battery health, or cold-weather loss.
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Power station model
Device scenario
Output path
Fridges cycle on and off. The calculator treats the entered wattage as compressor running wattage and applies a duty-cycle estimate.
Estimated runtime
4h 58mThis setup is tight. Reduce load, use DC where possible, or choose a larger station.
Usable energy819 Wh
Average load165 W
Running watts500 W
Max surge1500 W
Conservative3h 6m
Estimated4h 58m
Optimistic6h 10m
- 1070 Wh nominal battery capacity
- AC inverter output path
- 85% conversion efficiency
- 10% reserve kept unused
- 165 W average load from 1 load
- 100% battery health
- 0% temperature loss
- This is an estimate. Real runtime changes with load, temperature, battery age, AC/DC output, and device behavior.
Source-Backed Next Steps
Smallest matching recordPecron E2000LFPBest for
Estimate outage runtime for refrigerator backup.
Inputs to check
- Battery capacity in watt-hours.
- Measured or realistic device watts.
- Efficiency, reserve, duty cycle, and output path.
Before relying on it
- Check startup surge for motors and compressors.
- Use a watt meter for critical outage or medical-adjacent loads.
- Keep source confidence visible when comparing models.
This calculator gives a planning estimate. Treat the result as a starting point, then refine it with measured watts, the device manual, and the station's current output limits.
Related Calculators
Use the related tools when charging, sizing, surge, or power path changes the answer.
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FAQ
These answers keep the estimate grounded in assumptions instead of pretending runtime is exact.
How do you calculate portable power station runtime?
Use usable watt-hours divided by average load watts. For AC loads, a practical first-pass formula is battery Wh x efficiency x reserve factor divided by device watts.
Why is real runtime lower than the label capacity?
Battery label capacity is nominal. Inverter losses, DC conversion losses, reserve settings, cold weather, battery age, and changing device loads all reduce real runtime.
What efficiency should I use for AC devices?
Use 80% to 90% for most AC inverter loads unless you have measured data. The default calculator value is 85%.
What efficiency should I use for DC devices?
DC loads can often do better than AC because the inverter stays off. Use 88% to 95% only when the voltage path is appropriate and the device is stable.
Can a power station run a refrigerator overnight?
Often yes, but the answer depends on battery Wh, fridge running watts, compressor duty cycle, room temperature, and startup surge. Always check surge capability.
Why does the fridge setting use a duty cycle?
Refrigerator compressors cycle on and off. The calculator uses duty cycle to convert running watts into a more realistic average load.
How many watt-hours does a CPAP need overnight?
A CPAP without heated humidification may use roughly 240 to 480 Wh over eight hours. Heated humidifiers and tubes can raise that substantially.
Can I use this for medical backup planning?
Use it only as a planning estimate. For medical devices, follow the manufacturer guidance and keep a tested backup plan.