Choose CPAP Backup Power by Compatibility, Runtime and Switchover

Choose a backup that supports your exact CPAP model and can cover your entire sleep period—with reserve. Battery capacity alone is not enough: the connection, humidifier settings and ability to switch automatically also matter.

If power has already failed and airflow stops, remove your mask while restoring power. ResMed’s AirSense 11 user guide warns that wearing the mask without airflow can cause rebreathing of exhaled air. If you have no working backup, contact your equipment supplier or prescribing clinician for your outage plan; do not assume skipping treatment is safe. The American Lung Association recommends discussing alternatives with your healthcare provider.

This guide covers sleep-apnea CPAP backup, not a life-support ventilation plan. If you depend on powered equipment to stay alive and it cannot operate, FDA guidance is to seek emergency services immediately.

Match the power source to the machine

Start with the model number—not just the brand. Ask your supplier to confirm the approved battery, cable or converter, and whether heated humidification is supported.

Backup option	What to verify before relying on it
Model-compatible CPAP battery	Correct cable and voltage; runtime at your settings; whether it supports automatic backup
Portable power station	Compatible AC output with the original power supply, or a supported DC port and model-specific converter; usable capacity
UPS	Permission for this use in both manufacturers’ instructions; output waveform; runtime at the actual load; transfer behavior

Do not connect a generic battery directly just because its plug fits. For example, ResMed’s Air10 converter takes a 12V or 24V DC source and supplies 24V/90W for AirSense 10 or AirCurve 10 devices. The AirSense 11 manual lists a separate Air11 DC/DC converter and warns against inserting a USB cable into the machine.

For models covered by its 2018 battery guide, ResMed favors its appropriate DC/DC converter over an inverter because the converter is more efficient. Do not apply that guide’s inverter recommendations to unlisted machines. If using AC backup, check your current device instructions for waveform and power requirements.

Calculate watt-hours, not just watts

Watts (W) describe the load the backup must supply. Watt-hours (Wh) describe stored energy and help estimate how long it can run. A large output rating does not establish overnight runtime.

The power brick’s rating is not a measurement of your nightly consumption. For example, the AirSense 11 specifications list a 65W power supply, 56.1W typical consumption and 73.2W peak consumption. Your own settings still need verification.

For an initial estimate:

Required delivered energy = average watts × hours of use

Estimated nameplate capacity = delivered energy ÷ usable fraction

These hypothetical loads assume eight hours of use and 80% usable energy after conversion losses and cutoff. That is an illustrative assumption, not a verified efficiency for any product. Reserve is not included.

Average load	Energy for 8 hours	Nameplate capacity at 80% usable
15W	120Wh	150Wh
30W	240Wh	300Wh
60W	480Wh	600Wh

At 60W, adding an illustrative 25% reserve raises the target from 600Wh to 750Wh for one eight-hour night, or 1,500Wh for two nights without recharging. Neither figure guarantees runtime. Use measured overnight consumption or the manufacturer’s model-specific runtime data to refine it. Measurements should include the power supply or converter you intend to use.

For broader system choices, see our home-outage battery guide.

Humidifier and heated tubing can change the answer

ResMed’s 2018 deep-cycle battery table gives a useful model-specific comparison. For listed AirSense 10 models at 10 cm H₂O, using the appropriate ResMed DC/DC converter, its eight-hour 12V deep-cycle battery sizes are:

• 12Ah with SlimLine tubing and no heated humidification listed.
• 28Ah with SlimLine tubing and humidifier setting 4.
• 46Ah with ClimateLineAir tubing and automatic humidification.

Those figures already include ResMed’s stated 50% safety margin. The guide uses the 95th-percentile pressure for AutoSet products; ask your supplier which pressure entry applies to your machine. These are deep-cycle battery recommendations—not universal lithium-battery or AirSense 11 specifications. An amp-hour rating cannot be compared across batteries without also checking voltage.

Ask your clinician or supplier whether reduced or disabled heating is appropriate for your backup plan. Change only permitted comfort settings, not prescribed pressure to save energy. The AirSense 11 manual provides separate humidity and tube-temperature controls, including off settings.

Prove the backup before bedtime

A battery that requires manual reconnection does not provide automatic overnight backup. Verify the manufacturer’s supported backup configuration; do not assume “pass-through charging” means uninterrupted operation.

Following the manufacturers’ instructions, test loss of wall power while awake, with the CPAP operating and someone able to intervene. Confirm airflow continues; if it stops, remove your mask and verify how to restart therapy. Check that prescribed settings remain correct after power returns, as the FDA recommends for medical devices.

Verify enough runtime for your full sleep period plus reserve using manufacturer data and a monitored trial. Do not deliberately run the battery to shutdown while asleep. The American Lung Association recommends practicing the plan and testing backup sources.

Keep a written record of the cable, settings, tested duration and recharge method. Follow the battery’s storage schedule and retest as it ages: ResMed’s compatibility guidance identifies settings, leaks, breathing pattern, environment and battery age as runtime variables.

Arrange a powered destination before the battery runs out; confirm it can accommodate your equipment. If using a portable generator to run or recharge the backup, keep it outdoors, at least 20 feet from doors, windows and vents, per CDC guidance—never inside a home or garage.

Reviewed October 9, 2026. No affiliate links or product rankings.