Emily ParkerBy Emily Parker

Updated November 2026

An ecoflow delta 3 plus can keep a refrigerator, a CPAP machine and a sump pump running through a power outage, but only if the battery is sized correctly for those loads. This guide shows you how to total your critical devices, convert their power draw into watt-hours and estimate how long the station will last. You will finish with a realistic runtime estimate you can act on.

Step 1: List Only the Loads You Need to Run

Start by listing the devices you want to keep powered during an outage. Limit the list to essentials, because every extra device shortens runtime. Most households focus on a refrigerator, a CPAP machine, a sump pump, a few lights and a phone charger.

Shopping for one? See our guide: EcoFlow Delta 3 Max Plus Review: Features and Performance.

  • Refrigerator: typically 100 to 400 watts while the compressor runs, with a lower average draw over time
  • CPAP machine: often 30 to 90 watts while running, depending on the model and humidifier use
  • Sump pump: commonly 500 to 1,000 watts while running, with a high startup surge
  • LED lights and phone chargers: usually under 20 watts each

Check the nameplate label on each device or the manufacturer’s manual for exact wattage. These ranges are general, so your numbers may differ.

Step 2: Convert Power Draw Into Watt-Hours

Battery capacity is rated in watt-hours (Wh), so you need to convert each device’s usage into that unit. Multiply the device’s running watts by the hours you expect to use it, then add the results together. For example, a 60-watt CPAP running 8 hours uses 480 Wh per night.

Refrigerators cycle on and off, so their average consumption is far lower than their peak draw. Many owners estimate refrigerator use at roughly 1 to 2 kWh per day, though your appliance may differ. Sump pumps run only when water rises, so their daily energy use is usually small unless flooding is severe.

Step 3: Estimate Runtime and Add a Safety Margin

Divide the station’s usable watt-hours by your total daily load to estimate runtime. Power stations do not deliver their full rated capacity, because inverter conversion and battery management consume some energy. Plan for usable output below the rated figure, and keep a buffer of at least 20 percent for surprises such as longer outages or cloudy days if you plan to recharge with solar.

Load Estimated Daily Use
CPAP (60 W, 8 hours) About 480 Wh
Refrigerator (average) About 1,000 to 2,000 Wh
Sump pump (occasional) Varies widely with water events
LED lights and chargers About 100 to 200 Wh

The table above gives rough starting points only. Measure your own devices with a plug-in watt meter for the most reliable numbers.

Step 4: Plan Recharging and Priority Loads

Runtime is only half the picture. You also need a way to recharge if the outage lasts longer than the battery. Wall charging works when grid power returns, and solar input can extend operation during multi-day events. Check the input limits in the official manual before connecting panels.

If your total load exceeds what the station can supply continuously, prioritize. Run the CPAP and refrigerator first, and power the sump pump only during high-water events. Shifting loads this way often matters more than buying a larger battery.

  • A plug-in watt meter helps you measure real device consumption instead of relying on label estimates. View on Amazon
  • A heavy-duty extension cord rated for outdoor and generator use keeps connections safe when the station sits away from appliances. View on Amazon

Common mistakes to avoid

  • Using the rated battery capacity as your runtime without accounting for conversion losses.
  • Ignoring sump pump startup surges, which can briefly exceed the running wattage.
  • Forgetting that a refrigerator runs intermittently, so peak watts overstate daily energy use.
  • Running space heaters or electric dryers, which draw far more power than the essentials listed here.
  • Skipping a test run, so you learn the actual runtime only during a real outage.

For a deeper comparison of models and capacities, see EcoFlow Delta 3 vs Delta 3 Plus: Which Power Station Fits Your Backup Needs? and Ecoflow Delta 3 Series Smart Extra Battery: A Practical Guide (2026).

FAQ

Can an ecoflow delta 3 plus run a refrigerator overnight?

It often can, because refrigerators cycle and average far less energy than their peak draw. Your actual runtime depends on the appliance’s efficiency, room temperature and how often the door opens.

How do I know if the sump pump will overload the station?

Check the pump’s running watts and its startup surge rating in the manual, and confirm the station’s continuous output and surge limits. If the pump’s surge exceeds those limits, it will not run safely.

Should I consult a professional before wiring a power station into my home?

Yes. Transfer switches and wiring into household circuits should be installed by a licensed electrician to avoid backfeeding the grid and to meet local electrical codes.

Conclusion

To size an ecoflow delta 3 plus correctly, list only your essential loads, convert them into daily watt-hours and divide the usable capacity by that total. Build in a safety margin and plan how you will recharge. Test the setup once before you need it, and you will know your real backup window.

Ready to choose one?

Emily Parker

About Emily Parker

Emily Parker is part of our editorial team and reviews and edits our solar generators for home backup & emergencies guides, checking product details against manufacturer specifications and owner feedback.