CPAP Backup Power: How to Sleep Through Any Outage

The Load Everyone Gets Wrong

A CPAP machine itself is a small, friendly load: about 40W. Turn on the heated humidifier and heated tube, and the same machine draws about 120W — triple the energy, one third the nights per charge. Most "my battery died at 2 AM" stories trace back to this single setting.

This guide covers the real math: nights-per-charge for every station in our database, why the humidifier is optional in an outage, the DC adapter trick that stretches runtime further, and the safety caveats that belong in any article about powering a medical device.

First, the obligatory note, stated plainly: a power station is not a medical device, and nothing here is a guarantee of uninterrupted therapy. Spec-sheet modeling can't account for your specific machine, pressure settings, or altitude. If your therapy is critical, talk to your provider about battery backup designed and rated for your device, and treat a power station as a margin layer — sized with headroom, not to the decimal.

The Math

An 8-hour night at each setting:

CPAP alone:        40W × 8h  = 320Wh per night
CPAP + humidifier: 120W × 8h = 960Wh per night

Usable battery energy = rated Wh × 0.85 (inverter and conversion losses). Nights per charge = usable Wh ÷ nightly Wh.

Nights-Per-Charge Table

Modeled for every station in our spec database, 8-hour nights:

Station	Wh	Nights @ 40W (no humidifier)	Nights @ 120W (humidifier on)
EcoFlow RIVER 3	245	0.7	0.2
Bluetti EB3A	268	0.7	0.2
Anker SOLIX C300	288	0.8	0.3
Jackery Explorer 300	293	0.8	0.3
Goal Zero Yeti 500X	505	1.3	0.4
EcoFlow DELTA 2	1,024	2.7	0.9
EcoFlow DELTA 3 Plus	1,024	2.7	0.9
Anker SOLIX C1000	1,056	2.8	0.9
Jackery Explorer 1000 v2	1,070	2.8	0.9
Bluetti AC180	1,152	3.1	1.0
Jackery Explorer 2000 Plus	2,042	5.4	1.8
Anker SOLIX F2000	2,048	5.4	1.8
EcoFlow DELTA Pro 3	4,096	10.9	3.6

Read the right-hand column first. With the humidifier on, no sub-$300 station survives a third of one night, and even the 1kWh class doesn't reliably finish a full night. With the humidifier off, the picture flips: the small stations cover most of a night and the 1kWh class covers a long weekend. Model your own machine's wattage at the runtime calculator, and see the appliance profile on the CPAP can-it-run page.

Trick 1: Kill the Humidifier (You'll Be Fine for a Few Nights)

In an outage, turn the humidifier and heated tube off. Therapy pressure — the part that treats the apnea — is unaffected; you lose comfort features. Most machines also support passover humidification (water in the tank, heater off) at zero added wattage. Dry mouth for two nights is a fair trade for therapy that lasts the whole outage. If congestion makes the humidifier non-negotiable for you, that's a sizing input, not a footnote: budget 960Wh per night and shop the 2kWh tier and up.

Trick 2: The DC Adapter

Running a CPAP on the station's AC outlet pays the conversion tax twice: the station inverts battery DC to 120V AC, then your machine's power brick converts it straight back to low-voltage DC. The inverter also burns idle overhead all night just by being on — a fixed cost that's proportionally brutal under a 40W load.

Most major CPAP machines accept a manufacturer 12V/24V DC power cable that plugs into a power station's car-socket (12V) output, bypassing the AC inverter entirely. The double conversion and inverter idle drain disappear, and more of the rated watt-hours become therapy hours — meaningfully so on small stations, where inverter overhead is a large slice of a 320Wh night. The cable is machine-specific and costs far less than the next battery size up. One caveat: humidifier performance on DC varies by machine (some disable or limit heating on DC) — check your machine's documentation.

The Picks

Best dedicated CPAP battery: Anker SOLIX C300

The Anker SOLIX C300 (288Wh, 9.3 lbs, LFP, WattScore 80) covers ~0.8 of a night on AC — and a DC cable closes most of that gap to a full night. LFP chemistry matters here: a CPAP backup sits charged and idle for months, the exact condition that degrades the NMC-based Jackery Explorer 300 (293Wh, WattScore 74) fastest. It recharges 0–80% in 50 minutes, so a daytime grid window resets you for the next night.

Verdict: the right buy for travel and bedside outage duty, humidifier off, DC cable in the bag. Skip it if you won't give up the humidifier — no sub-300Wh unit works at 120W.

Best value with a margin: Bluetti EB3A

The Bluetti EB3A (268Wh, 600W/1,200W, 10.1 lbs, WattScore 81) gives up 20Wh to the C300 but carries a 600W inverter — double the C300's 300W — which makes it the small unit that can also run a fan, charge phones, and absorb whatever else gets plugged in at 2 AM without faulting. Also LFP, also fast to recharge (0–80% in 45 minutes).

Verdict: buy it if the CPAP battery will inevitably become the family's outage outlet strip. Skip it for strict single-device duty where the C300's extra capacity wins. Numbers side by side: EB3A vs SOLIX C300.

Whole-night humidifier, multi-night therapy: EcoFlow DELTA 2

The EcoFlow DELTA 2 (1,024Wh, 27 lbs, WattScore 88) models 2.7 nights without the humidifier and ~0.9 of a night with it — the practical floor for anyone unwilling to sleep dry. It's also a fridge-capable station (1,800W/2,700W), so it doubles as general home backup, and 0–80% takes 50 minutes.

Verdict: the right size if CPAP is one of several loads, or the humidifier is staying on. Skip it if you want grab-and-go portable; 27 lbs isn't a nightstand unit. The Goal Zero Yeti 500X (505Wh, 1.3 nights) sits between the classes, but its NMC chemistry and 300W inverter make it hard to recommend over spending slightly more for the DELTA 2.

Sizing Rule of Thumb

• 1 night, no humidifier: ~375Wh rated minimum (320Wh ÷ 0.85). Any 300Wh-class unit plus a DC cable gets there.
• 3 nights, no humidifier: ~1,130Wh rated → the 1kWh class.
• Per night with humidifier: ~1,130Wh rated per night → 2kWh class for a weekend, the DELTA Pro 3's 4,096Wh for 3.6 nights.
• Always size with a margin night. Batteries age, nights run long, and pressure settings vary. Full ranked list at /stations.

FAQ

How many watt-hours do I need to run a CPAP for one night?

About 320Wh of delivered energy for an 8-hour night at 40W — roughly 375Wh of rated capacity after the 0.85 conversion derate. With a heated humidifier (120W total), it's 960Wh delivered, or about 1,130Wh of rated capacity per night.

Does the humidifier really triple CPAP power draw?

Per our appliance model, yes: ~40W for the blower alone versus ~120W with the heated humidifier and tube running. It is the single largest factor in CPAP backup sizing — larger than the choice between any two stations in the same class.

Can I run a CPAP off a power station's 12V car port?

Most major machines offer a manufacturer DC cable for exactly this. It bypasses the AC inverter and its idle overhead, delivering more therapy hours from the same battery. Verify your machine's cable and whether humidifier function is limited on DC power.

Will a power station switch over automatically if the grid fails at night?

Stations with passthrough/UPS-style charging keep the CPAP powered from the wall and switch to battery when the grid drops. Switchover times vary by model and are not medical-UPS rated — another reason to size with margin and discuss critical therapy with your provider.