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Your CPAP Sips 10 Watts. So Why Does It Kill a Battery in One Night?

The humidifier does. On a ResMed AirSense 11 the blower draws 10 W and the heater plate and heated hose 47 W, so heat is 82% of the draw: a 500 Wh station runs the heated setup about 6 hours and the dry one about 3 nights. We modeled 61 stations, heat on and off, AC and 12 V DC, to find the ones that reach morning.

See the picks Plan your nights

Researched & scored by Brennan Noailles·Written by Ian Schneider·Our method →

UPS mode on every pickEvery assumption disclosedNo sponsored rankings
The short list

Where most people should start

I picked these on paper, from the specs that decide a night. How fast the station switches to battery. How loud it is next to a pillow. A LiFePO4 pack (lithium iron phosphate, the chemistry that takes years of nightly cycling). One is for a weekend away, one lives by the bed, one is for a long outage. The planner below sizes your exact machine and settings.

Explorer 300 v2

Travel & weekends

Jackery Explorer 300 v2

The one you actually pack.

288 Wh · 8 lb · 10 ms cutover · 12 V/10 A socket · LiFePO4

Eight pounds, with a 12 V car socket we checked against Jackery’s spec sheet. Your machine’s DC cord plugs straight into it. On that silent path it carries about three heat-off nights, or half of a humidified one. Jackery doesn’t publish a noise figure. If you sleep light, Anker rates its SOLIX C300 at 25 dB, for a pound more and about $60 more.

DELTA 3 Classic

The nightly bedside UPSwhat most readers need

EcoFlow DELTA 3 Classic

Plugged in, forgotten, ready.

1,024 Wh · 10 ms cutover · 30 dB · LiFePO4

It sits between the wall and your machine. When the grid fails it takes over in 10 milliseconds, a gap your machine is built to ride through. You will be asleep for it. A night and a half with the humidifier on, six with the heat off.

Elite 200 V2

Long outages & off-grid

BLUETTI Elite 200 V2

Quieter than your fridge, for nights on end.

≈2 kWh · 10 ms cutover · 16 dB · solar-ready

BLUETTI rates it at 16 dB, which is close to silent beside a bed. Two kilowatt-hours is three humidified nights. Or it is the CPAP plus the fridge through a long outage.

How a night is lost

The science of a reliable night

Some batteries carry you to morning without a sound. Others wake you at 3 a.m. Here is one night, hour by hour. Four things decide how it goes, and capacity is only one of them.

11:04 PM

The humidifier is a small kettle

The blower that pushes your air is a tiny brushless motor. It sips around 10 watts. The battery goes on heat. The humidifier's heater plate and the heated hose are plain resistive elements, so electrically you are running a small kettle all night. Warming water takes far more energy than moving air. Together they pull 30–45 watts of pure heat. That is why the humidifier and tube account for up to ~80% of a running machine's draw. Left on, they turn a four-night battery into a one-night battery.

So size the battery on the watts with the humidifier on. Switching the heat off in an outage can stretch the same battery roughly five times further. It is worth finding that setting in daylight, before the night you need it.

Where a CPAP's watts go

Heat on
heat ≈ 80% of the draw
≈ 55 W
Heat off
≈ 10 W
Blower 10 WHumidifier ~30 WHeated tube ~15 WHeat off: the same battery lasts roughly 5× longer
Fig. 1 · The blower barely sips. The heater plate and heated hose do the draining. The humidifier switch is your biggest runtime lever.

Worth knowing

In an outage, turn off the heated humidifier and tube first. It is the biggest lever you have, often 3–5× the runtime, and ResMed's own manual says to turn the humidifier off on an external battery. Keep a model-specific DC converter cable in the drawer as well. It lets you skip the inverter and the fan that comes with it.

12:52 AM

Your CPAP already runs on DC

Look at your power brick. It turns wall AC into low-voltage DC before a single breath. On most ResMed machines that is 24 V. Run the machine off a power station's AC outlet and the energy gets converted twice. The station's inverter (the part that makes wall-style power) lifts the battery's DC up to 120 V AC. Then the brick turns it straight back into DC. The round trip loses 15–25%.

The inverter also has a cooling fan, and it runs all night about a foot from your head. A model-specific DC converter cable into the station's 12 V port skips both conversions. You get 15–25% more runtime and the fan stays off. If I slept on a CPAP, I'd run it from that cable and leave the AC outlet to the phone chargers.

The cable for your machine:ResMed AirSense 10/11 →Philips DreamStation →

3:17 AM

The grid fails. The next 17 milliseconds are the ones CPAP makers test.

CPAP makers test their machines against a complete loss of mains power for one cycle: about 17 ms on US power. ResMed lists that test for its AirSense 10 and 11, Philips for the DreamStation 2, and both recommend a UPS if the machine has to keep running through anything longer. A power station with a true UPS mode sits between the wall and the machine and takes over the moment the wall stops. Some makers call it EPS. One that switches to battery in 10 ms stays inside that tested window.

Past 17 ms, no maker publishes what happens. A machine may ride through a 20–30 ms switch, or it may stop. If it stops, ResMed's AirSense 10 restarts therapy by itself when power returns. You lose a moment of pressure and keep the night. A station with no UPS mode does nothing when the wall fails. The machine stays off until the power comes back, or until you wake up, find the plug in the dark and move it. For a CPAP, the switchover is the feature you are paying for.

When the grid blinks: does your CPAP notice?

UPS 10 ms
UPS 20–30 ms
No UPS mode
grid failstested
✓ tested window
may stop, then restart
✕ off
0 ms40 ms60 ms≈17 ms
Fig. 2 · ResMed and Philips test their CPAPs against a full loss of mains for one cycle, about 17 ms on US power. A 10 ms switch sits inside that window. No maker publishes what happens at 20–30 ms: the machine may ride through or stop, and ResMed's AirSense 10 restarts therapy by itself when power returns. With no UPS mode, nothing switches at all.

The spec that matters

For medical backup, read the switchover time before the capacity. A true UPS rated 10 ms or less sits inside the dropout CPAP makers test their machines against.

6:41 AM

Sizing for the whole night

The arithmetic is short. Battery capacity is counted in watt-hours (Wh): one watt for one hour. Take your average watts, multiply by the hours you sleep, and divide by the efficiency. On the 12 V DC path about 95% of the battery’s energy reaches the machine. Through the inverter it is about 80% at CPAP-sized loads, once you count the inverter’s own draw. A humidified 55 W setup over 8 hours takes about 460 Wh from the battery on DC and 550 Wh through an inverter. Only about nine tenths of a station’s rated capacity is usable. So one humidified night needs roughly 520 Wh rated on DC and 610 Wh on AC, and a “500 Wh” station runs out before morning: about 6½ hours through the AC outlet, 7½ on a DC cord.

Two wrinkles. At altitude the blower spins faster to hold your prescribed pressure, so the draw creeps up. Up here in Truckee I'd leave a little extra margin for that. And running with the heat off buys runtime with comfort. Expect a dry throat, or "rainout", which is condensation collecting in the hose. It is a fine emergency move. I wouldn't make a habit of it.

Sources: ResMed’s power measurements of its Air10 machines, where the humidifier and heated tube make up about four fifths of the draw, and its AirCurve 10 user guide (humidifier off on an external battery); CPAP component power breakdown (Enticare ENT); the one-cycle dropout test from ResMed’s EMC declaration for its Air10 and Air11 machines and the DreamStation 2 manual; the automatic restart from ResMed’s AirSense 10 and AirStart 10 user guides. Figures are typical ranges. Check your machine's label and manual.

Plan your nights

The CPAP backup planner

Tell it your machine and how many nights you need covered. Add your partner's if there are two of you. It answers with the stations that last that long, and the outlet each machine plugs into.

Heat off ≈ 3–5× the nights12 V DC is silent, +15–25%10 ms switchover sits inside the makers' test

Start with your machine

Choose the model. Every number below follows from its draw.

Your machine
≈57W
Nights it must cover

The link reopens this planner with your exact setup.

Your answer

To sleep 1 night, you need

630Wh rated

≈566 Wh per night as configured

heat off: ≈139 Wh, your biggest lever

DELTA 3 Classic

Our pick for this setup

EcoFlow DELTA 3 Classic

1,024 Wh · 10 ms cutover · 30 dB · $479

Check price at EcoFlow
  • ResMed AirSense 11AC outlet (pure sine wave)

Charge left, hour by hour

as configuredheat off
100%10% reserve
45%86%
11 PM7:00 AM

Reaches 7:00 AM with ≈45% left · heat off: ≈86% left.

4 more that fit · of 36

Estimates, not guarantees. Assumes 90% of rated capacity usable, 88% inverter efficiency plus ~6W inverter overhead on the AC path, 95% on the DC path. Typical draws from manufacturer power-supply ratings (e.g. ResMed 90W PSU ceiling) and owner-reported overnight measurements: an AirSense 11 with heated humidifier + tube averages ~50–57W (85W peaks) and ~10–15W with heat off. Check the label on your own power brick — pressure and humidity level move the real number.

Look it up later

CPAP nights per station: quick reference

Nights of ResMed AirSense 11 runtime (8-hour nights) on stations that cut over in 15 ms or less and stay at or under 40 dB. A machine with a similar draw lands close. The planner above models your exact setup, including two machines.

StationHumidifier on · ACHeat off · ACHeat off · 12V DC
EcoFlow RIVER 3 PLUS$299≈0.5≈1.9no 12V socket
Anker SOLIX C300$429.99≈0.5≈1.9≈3.1
BLUETTI Elite 30 V2$289.99≈0.5≈1.9≈3.1
Anker SOLIX C300X$299.99≈0.5≈1.9no 12V socket
Jackery Explorer 300 v2$279≈0.5≈1.9≈3.1
EcoFlow RIVER 3 MAX$319≈0.9≈3.7no 12V socket
Goal Zero Yeti 1000 (6th Gen)$1,199.95≈1.6≈6.4no 12V socket
Jackery HomePower 1000 Plus v2$749≈1.6≈6.6no 12V socket
BLUETTI Elite 100 V2$499≈1.6≈6.6≈10.9
EcoFlow DELTA 3 Classic$479≈1.6≈6.6no 12V socket
Fig. 3 · Nights (8h) of ResMed AirSense 11 runtime per station. Assumes 90% of rated capacity usable; AC path at 88% inverter efficiency + ~6W inverter overhead; DC path at 95%. AirSense 11 draws ≈57W with heated humidifier + tube, ≈10W without. "No 12V socket" reflects the manufacturer's published port list.
Still awake?

Common questions

Short answers to the questions people ask before they buy.

Generally, no. TSA and FAA regulations strictly limit lithium batteries to 100Wh (or 160Wh with airline pre-approval). A typical humidified CPAP needs roughly 520 Wh of rated capacity on a 12 V DC cord, or 610 Wh through the AC outlet, to last a full 8-hour night, so most power stations are legally grounded. The best strategy is to carry a flight-approved 'travel battery' like the Medistrom Pilot-24 for the flight itself, and have your larger power station waiting at your destination or shipped ahead.

Worth knowing

If you must travel frequently, consider buying multiple 100Wh modular batteries. Some companies make flight-approved battery banks that link together once you reach your destination to create a larger capacity.

Yes, if the unit has a true UPS (EPS) mode that switches over inside the dropout CPAP makers test against: about 17 ms on US power, and 10 ms on this guide's short-list picks. Units built for this sit plugged in between the wall and the machine, and the wall runs your CPAP until the power fails. Two checks before you rely on one: ask your CPAP's maker whether it can run on a battery or inverter, and sleep one full night on the battery at home so you know your real margin.

Worth knowing

To maximize the lifespan of your unit in UPS mode, check the app settings to see if you can limit the max charge to 85% or 90%. Keeping lithium batteries slightly below 100% reduces cell stress.

Makers rate this guide's bedside picks at 16dB to 30dB, and the reference table only lists stations rated 40dB or less. However, the fan kicks in when the internal inverter gets hot. The key to silence is bypassing the AC inverter completely by using a DC-to-DC cable.

Worth knowing

If you use a DC power cord for your CPAP instead of the standard AC wall plug, the power station's inverter stays off. This generates almost zero heat, keeps the fan completely silent, and buys you 15–25% more runtime.

It depends almost entirely on the humidifier. A typical humidified setup runs about 6½ hours on a 500 Wh station through the AC outlet and 7½ on a 12 V DC cord, so not quite a full 8-hour night. With the heat off it is about 3 nights on AC and 5 on DC. Leave some headroom for battery ageing; the planner above sizes your own machine and settings.

Yes, this is non-negotiable. Medical devices are sensitive electronics. A 'Modified Sine Wave' (found in cheap, generic batteries or old vehicle inverters) provides choppy power that can cause motor hum, excess heat, or permanently damage your machine’s motherboard. All major brands we recommend (EcoFlow, Bluetti, Jackery) use Pure Sine Wave inverters that cleanly mimic the power from your home wall outlet.

Yes, as long as each day of sun puts back what a night takes out. A 100W panel in good sun delivers well under 100W once heat, angle and wiring losses take their share, so refilling a 500Wh station takes most of a sunny day or more. A bigger panel refills it sooner, and cloud slows everything down. Check that the station's solar input accepts your panel's voltage before you plug it in.

Yes. Two machines draw 20–120W combined, well within any station's AC rating. For capacity, add both machines' draws and size for your target nights. Two heated ResMed setups need roughly 1,000Wh per 8-hour night, or around 200Wh with both humidifiers off. Ports are the catch. Most stations have only ONE 12V car socket, and CPAP DC converters plug into a car socket, not the DC5521 barrel outlets. The cleanest two-machine layout is one machine on the 12V socket and the second on an AC outlet.

Worth knowing

Don't split a single 12V socket between two heated machines. A 12V/10A (120W) socket can't safely feed two humidified setups at their peaks. Use the planner above with a second machine added. It assigns each machine to a specific outlet for any station whose ports we've checked against the maker's spec sheet.

This is the biggest efficiency lever in CPAP camping. Using the AC outlet wastes about 15–25% of your battery's energy just converting the DC battery power into AC wall power, only for your CPAP power brick to convert it back to DC. Buying a specific DC power cord for your CPAP (e.g., ResMed AirSense 10/11 DC Cable) allows you to plug directly into the 12V port, skipping the conversion and giving you significantly more runtime.

⚡ CPAP Backup Power Rankings

Top 3 per price range · Ranked by Sleep Therapy Reliability

Best Under $800Top 3
1

Anker SOLIX S2000

2,009.6 Wh · 1,500W

4,891

Price
2

Jackery HomePower 1000 v2

1,024 Wh · 1,500W

3,785

Price
3

Jackery HomePower 1000 Plus v2

1,024 Wh · 1,800W

3,745

Price
Best $800 – $2,000Top 3
1

BLUETTI Elite 200 V2

2,073.6 Wh · 2,600W

4,334

Price
2

Jackery HomePower 2000 Plus v2

2,048 Wh · 2,400W

4,164

Price
3

Anker SOLIX C2000 Gen 2

2,048 Wh · 2,400W

4,003

Price
Power Score is our proprietary benchmark across 14 spec dimensions. Higher = better. Value = score per $100 spent.How we score →

Pairs naturally with

The same battery, in the other situations it has to keep running.

🧮 Tool
Power Station Calculator

The planner here sizes the machine on its own. When the same battery also has to run a fridge, the Wi-Fi and phones, this sizes all of it together.

Size the whole list →
🩺 Tool
Medical Equipment Outage Plan

Oxygen, a ventilator or insulin in the house as well? The outage plan works out how long each device lasts on the battery and on its own backups, and when to switch to plan B.

Make an outage plan →
🔌 Guide
Best UPS Power Stations

Switchover speed is the spec that decides both. A CPAP is simply the highest-stakes thing you can put behind a UPS.

See UPS picks →
🚨 Guide
Emergency & Outage Backup

A CPAP through a multi-day outage stops being a switchover question and becomes a capacity one.

Read the outage guide →
⛺ Guide
Best for Camping

Same machine, different problem — overnight power where there is no outlet within a mile.

See camping picks →
Before the first night

Run the rehearsal

Whichever station you pick, prove it on a night that doesn't matter. One quiet weeknight is enough.

  1. 1

    Buy the DC cable the same day as the battery. The model-specific 12 V converter cable is what lets the machine run with the inverter off. Put it in the drawer now. Nobody sells one at 2 a.m.

  2. 2

    Sleep one full night on battery alone, at home. Charge to 100% and unplug it from the wall. Use your normal settings, humidifier and all. Then go to bed.

  3. 3

    Read the percentage in the morning. That number is your real margin. Trust it over every calculator, including ours. If it makes you nervous, so will the third night of an outage.

Compare CPAP-ready stations

Every spec on one grid: cutover, noise, capacity, ports.

Head to head

The picks, decided in pairs

Three picks for three different nights. If you are between two of them, read the pair.

Each pick on its own page: Jackery Explorer 300 v2 · EcoFlow DELTA 3 Classic · BLUETTI Elite 200 V2

Same units, different job