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Portable Power Station for CPAP: How Many Wh You Need (With the Math)

By the Power Station Guide research desk · Updated · Specs from manufacturer sources

Quick verdict

For a full night with the humidifier and heated tube on, plan on about 500–700 Wh from the battery (a ~1,000 Wh station covers roughly two nights). With heat off, needs drop sharply, and a 300–500 Wh station can often cover a night. Measure your own machine first.

Medical note: this guide covers power math, not therapy advice. If you depend on CPAP, talk with your doctor or equipment provider about outage plans, and ask your utility about priority restoration for medical equipment, as Ready.gov recommends.

The short answer

A CPAP doesn't need a big inverter. It needs enough watt-hours (Wh) for a full night. The number that decides your station size is your machine's average draw multiplied by the hours you sleep, plus conversion losses:

Wh needed per night ≈ CPAP watts × hours ÷ 0.85 (when plugged into the station's AC outlet)

The 0.85 factor is the same conservative allowance for inverter and conversion losses we use in our power station sizing guide. Real efficiency varies by model and load.

These are the published power-supply figures from each manufacturer's user guide. They describe the whole system, so they're a sensible planning number for a night with comfort features on.

Machine Power supply Typical draw Peak draw 8-hour energy at typical draw From battery via AC (÷ 0.85)
ResMed AirSense 11 65 W, 24 V 56.1 W 73.2 W ~449 Wh ~528 Wh
ResMed AirSense 10 90 W, 24 V 53 W 104 W ~424 Wh ~499 Wh
Philips DreamStation 2 Not listed as watts in the user manual n/a n/a Measure yours Measure yours

Peak draw happens briefly (for example while the humidifier heats up), so don't multiply the peak by 8 hours unless you want an extreme worst case: for the AirSense 11 that would be ~586 Wh at the machine, or ~689 Wh from the battery.

Philips doesn't publish a typical wattage for the DreamStation 2 in its manual, but it does state that an 80 W power supply is required to support humidification, and that when running from a battery adapter the device may report that humidification isn't supported. If you use a DreamStation 2, plan on running dry from DC, or measure your AC draw.

The humidifier and heated tube are the big variables

The blower itself uses relatively little power. Heating water and the hose is where most of the energy goes. ResMed's AirSense 10 user guide says plainly: if you are using an external battery, turn off the humidifier to maximize battery life.

Manufacturers don't publish a "humidifier off" wattage, and it changes with your pressure setting, so measure it:

  1. Charge the power station fully and plug the CPAP into it (or use a plug-in watt meter at the wall).
  2. Run a normal night with your usual settings.
  3. In the morning, note the percentage used. Wh used ≈ station capacity × % used.
  4. Repeat one night with humidity and tube heat off if you plan to run dry during outages.

That one test replaces every estimate in this article, including ours.

Worked example: dry mode (illustrative number, not a spec)

Suppose your measurement shows an average of 20 W with heat off. Over 8 hours that's 160 Wh at the machine, or about 188 Wh from the battery on AC. Use your own measured figure in place of 20 W.

How many nights will a station last?

Nights ≈ (station Wh × 0.85) ÷ (CPAP W × 8 hours)

Station capacity At 56.1 W (AirSense 11 typical, on AC) At 20 W (illustrative dry mode, on AC)
300 Wh ~4.5 h (0.6 nights) ~12.8 h (1.6 nights)
500 Wh ~7.6 h (0.9 nights) ~21 h (2.7 nights)
1,024 Wh (EcoFlow DELTA 2) ~15.5 h (1.9 nights) ~43 h (5.4 nights)
1,070 Wh (Jackery Explorer 1000 v2) ~16 h (2.0 nights) ~45 h (5.7 nights)
2,000 Wh ~30 h (3.8 nights) ~85 h (10.6 nights)

Two takeaways:

  • Under 500 Wh is a "humidifier off" setup. At ResMed's typical figure, a 500 Wh station falls just short of an 8-hour night on AC.
  • The ~1 kWh class is the comfortable outage pick: about two full nights with heat on, or most of a week dry. If you expect multi-day outages, see our size tiers or a model that accepts an extra battery.

AC outlet or DC cable?

AC (plug in the normal power brick): simplest, works with any machine, but the station converts battery DC to AC and the brick converts it back to DC. That double conversion is what our 0.85 factor covers.

DC (12 V car-style port or a dedicated cable): skips the double conversion, so the same battery usually lasts longer. Stick to the cable your machine's maker supports:

  • ResMed lists the Air11 DC/DC converter as an AirSense 11 accessory (the AirSense 10 equivalent is the Air10 DC/DC converter).
  • Philips states: only use a Philips Respironics DC power cord and battery adapter cable; use of any other system may cause damage to the device. It also warns not to run the device from a vehicle battery while the engine is running.

Manufacturers don't publish an efficiency figure for their DC converters, so we don't assign one. Your measured percentage-per-night will tell you the real gain.

Features that matter for CPAP backup

  1. Automatic switchover (UPS/EPS mode). If the station sits between the wall and your CPAP, it can take over when the grid drops, so you don't have to wake up and re-plug. EcoFlow states the DELTA 2 switches to battery within 30 ms; Jackery states the Explorer 1000 v2 switches in under 20 ms. EcoFlow also notes its basic UPS isn't a 0 ms system and advises testing compatibility first. Test it while awake: start the CPAP, then unplug the station from the wall and confirm therapy continues.
  2. Pure sine wave AC output. Check that the station's spec sheet lists pure sine wave AC output before plugging in a medical device's power brick.
  3. Battery chemistry and cycle life. If the station also does daily duty (camping, solar), LiFePO4 cells hold up to far more cycles. See LiFePO4 vs lithium-ion.
  4. Quiet operation and a small footprint. It lives on your nightstand, so cooling-fan noise matters. Run it overnight once before an outage to make sure you can sleep next to it.
  5. Recharge options. For multi-day outages, being able to top up from solar or a car during the day matters more than raw capacity.

Our picks for heated-humidifier nights (~1 kWh class)

Both have roughly two nights of AirSense 11 typical draw on AC, LiFePO4 cells and automatic switchover. The full spec breakdown is in EcoFlow DELTA 2 vs Jackery Explorer 1000 v2.

Best for portability

Jackery Explorer 1000 v2

  • 1,070 Wh LiFePO4 battery
  • 1,500 W continuous / 3,000 W surge
  • 3 AC outlets
  • Not expandable
  • ~23.8 lb · 3+2-year warranty
Check price at JackeryCheck price on Amazon
Best for home backup & expansion

EcoFlow DELTA 2

  • 1,024 Wh LFP battery
  • 1,800 W continuous / 2,700 W surge
  • 6 AC outlets
  • Expandable to 3,072 Wh
  • ~27 lb · 5-year warranty
Check price at EcoFlowCheck price on Amazon

Which one for CPAP? The Jackery is lighter (~23.8 lb) and lists the faster switchover (under 20 ms). The DELTA 2 can add an extra battery (up to 3,072 Wh per EcoFlow), which roughly triples the nights covered for longer outages.

Checklist before an outage

  • Measure one real night (heat on and heat off).
  • Keep the station charged, and follow its manual's guidance on how often to top it up in storage.
  • Have the right DC cable for your machine if you plan to run on DC.
  • Keep distilled water and a plan for which comfort settings you'll turn off.
  • Talk to your doctor or provider, and register with your utility for medical priority if available.

Frequently asked questions

How many watt-hours does a CPAP use per night?

Multiply your machine's watts by hours of use. ResMed lists typical consumption of 56.1 W for the AirSense 11 and 53 W for the AirSense 10, which works out to about 449 Wh and 424 Wh over 8 hours. Allow about 15% more when running through the station's AC outlet.

Can a 300 Wh power station run a CPAP all night?

Only with the humidifier and heated tube off. At ResMed's typical 56.1 W figure for the AirSense 11, a 300 Wh station lasts about 4.5 hours on AC. With heat off, draw is much lower, but measure your own machine before relying on it.

How long will a 1,000 Wh power station run a CPAP?

At 56.1 W on AC, a 1,024 Wh EcoFlow DELTA 2 gives about 15.5 hours (roughly two 8-hour nights) and a 1,070 Wh Jackery Explorer 1000 v2 about 16 hours. With lower dry-mode draw, expect several nights.

Is DC or AC better for running a CPAP?

DC is usually more efficient because it skips the battery-to-AC-to-DC double conversion. Use only the DC cable or converter your CPAP's maker supports, such as ResMed's Air11 DC/DC converter or Philips Respironics DC cords.

Does the humidifier really matter that much?

Yes. Heated humidification and heated tubing are the biggest loads. ResMed's AirSense 10 guide says to turn the humidifier off when using an external battery to maximize battery life.

Sources

Sources

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