If you use a CPAP, a power outage is not a minor inconvenience, it is a night without therapy. A portable power station fixes that, and the same unit covers you for camping, an RV, or anywhere off the grid. But CPAP backup has two quirks that ordinary “how big a battery do I need” advice misses, and getting them wrong is how people end up with a unit that dies at 2 a.m.
The first quirk is the humidifier. A CPAP motor by itself sips power, often only 30 to 60 watts. But the heated humidifier and heated hose are resistive heaters, and they can triple or quadruple the draw. The single biggest lever on how many nights a battery gives you is simply turning the humidifier and heated hose off. With them off, a small battery can run a CPAP all night; with them on, the same battery might not last until morning. Most people are fine without the humidifier for a night or two, and it roughly doubles to quadruples your runtime.
The second quirk is power compatibility. A CPAP is sensitive electronics, and cheap modified-sine car inverters can make a machine run hot or behave oddly. Use only an AC output, DC cord, and adapter that your CPAP manufacturer accepts for your exact machine.
I picked five units across the range, from an 8-pound travel battery that handles a dry night to a unit that covers two to three nights, so you can match the capacity to how you will use it: an occasional outage, regular camping, or a multi-day backup.
How Long Will a CPAP Run on a Battery?
This is the question everyone asks, and the honest answer is: it depends almost entirely on the humidifier. Here is the math, using realistic figures.
A CPAP with the heated humidifier and hose OFF draws roughly 40 watts, so over an 8-hour night it uses about 320 watt-hours. With the humidifier ON, the draw jumps to around 80 watts or more, so a night uses about 640 watt-hours, double. After accounting for the inverter’s conversion losses (roughly 15 percent), here is what each unit’s usable capacity translates to:
| Unit | Battery | Humidifier OFF | Humidifier ON |
|---|---|---|---|
| Bluetti EB3A | 268Wh | About 0.7 night | About 0.4 night |
| Jackery 300 Plus / Anker C300 | 288Wh | About 0.8 night | About 0.4 night |
| EcoFlow RIVER 2 Max | 512Wh | About 1.4 nights | About 0.7 night |
| EcoFlow DELTA 3 | 1024Wh | About 2.7 nights | About 1.4 nights |
The lesson jumps off the page: the small 288Wh units cover one night with the humidifier off, and only the DELTA 3 comfortably reaches two to three dry nights or more than one humidifier-on night in this estimate. If you need multiple nights, size up; if you turn the humidifier off, a small unit gets you through.
EcoFlow RIVER 2 Max
The RIVER 2 Max is the best all-around CPAP pick because it is the smallest unit that comfortably covers a full night even with the humidifier running. At 512Wh it gives you about one humidifier-on night or close to two dry nights per charge, which is the sweet spot for most people who want real outage backup without hauling a 27-pound unit. It is pure sine wave with a LiFePO4 battery rated for thousands of cycles, and it recharges fully in about an hour, so you can top it off fast before a storm.
The port selection helps with CPAP specifically. It has a 100-watt USB-C and a 12-volt DC output, which matters because many CPAPs can run directly off DC, skipping the AC inverter entirely (more on that below) for a meaningful runtime gain.
The trade-offs are modest. A single night with the humidifier on is about the limit per charge, so for multi-day outages you will recharge it (from a wall, a car, or a solar panel) or step up to the DELTA 3. It is more of a home-and-car-trip unit than the little travel batteries. For the most common need, one to two nights of reliable CPAP backup, it is the right size.
EcoFlow DELTA 3
The DELTA 3 is the pick when one night is not enough. In the estimate above, its 1024Wh capacity works out to roughly two to three nights with the humidifier off, or more than one full night with it on. Its 1800-watt continuous output is far above the CPAP loads used in that estimate. For a multi-day outage, a long off-grid stay, or anyone who relies on the humidifier and refuses to give it up, this is the capacity class that lasts.
It uses LiFePO4 cells, reaches 80 percent charge in 30 minutes and a full charge in 56 minutes, and expands up to 5kWh using compatible EcoFlow battery packs.
The trade-off is that 1024Wh is more battery than a single dry night needs, while solar input tops out at 500W. But if your honest requirement is “I must have CPAP therapy through a two- or three-day outage,” the capacity estimate gives you useful margin.
Jackery Explorer 300 Plus
The Explorer 300 Plus is the travel pick. At just 8.3 pounds it is genuinely packable, small and light enough to take on a plane or toss in a weekend bag, and it is pure sine wave with a LiFePO4 battery. With 288Wh it covers about one full night with the humidifier off, which is exactly what most travel and camping CPAP use needs: run the machine dry for the night and recharge during the day.
It has a 100-watt USB-C and a 12-volt DC output, so you can use the efficient DC-direct trick to stretch the runtime further, which matters a lot on a small battery.
Set expectations correctly: 288Wh is one dry night, not a humidifier night and not a multi-night unit. If you need the humidifier or more than one night, this is not the one, step up to the RIVER 2 Max or DELTA 3. But for the traveler who wants the lightest reliable way to run a CPAP for a night away from power, it is ideal.
Anker SOLIX C300
The SOLIX C300 is the other excellent compact option, and the one I would pick if DC-direct power is your plan. It is the same 8.3-pound, 288Wh travel class as the Jackery, pure sine wave and LiFePO4, but its standout feature is dual 140-watt USB-C ports, which give you flexible, high-output DC charging that suits running a CPAP off DC and topping off other devices at the same time. It also recharges in about an hour.
Like all the 288Wh units, it covers roughly one night with the humidifier off, and it is carry-on friendly for travel.
The honest limits are the same as its size class: one dry night, no humidifier night, and a slim 300-watt output ceiling that is fine for a CPAP but not for high-draw appliances. As a compact, well-built travel battery with the best USB-C setup here, it is a strong pick for the buyer who wants to run the machine efficiently off DC.
Bluetti EB3A
The EB3A is the budget weekend unit. It is a 268Wh pure sine wave battery, the smallest capacity here, but it carries the most surge headroom in its class (a 600-watt output with a 1200-watt surge), which gives it a comfortable margin to start the CPAP and run other small devices. It recharges quickly and has a 100-watt USB-C and a 12-volt DC port for the DC-direct trick.
For weekend camping or an occasional short outage, where you will run the CPAP dry for a night and recharge, it covers the job at the lowest cost.
Two honest notes. At 268Wh it is the smallest battery on the list, so it is a one-dry-night unit, full stop. And its cooling fan can be audible, which matters more than usual here because the whole point is to run it next to your bed while you sleep, so a light sleeper may notice it. For a budget buyer who wants surge headroom and only needs occasional single-night backup, it is a sensible pick.
How We Picked These
CPAP backup is a specific job, so the criteria are specific:
Power compatibility. A CPAP’s maker decides which AC output, DC cord, and adapter are safe for that machine. We treated that exact-model compatibility as non-negotiable.
Honest runtime. We did the actual watt-hour math for humidifier-on and humidifier-off nights rather than repeating marketing claims, so you can match capacity to how many nights you need.
DC output for efficiency. Running a CPAP off DC instead of AC can nearly double runtime, so we favored units with usable 12-volt DC or high-output USB-C ports.
The right size for the use. Travel, occasional outage, and multi-day backup are different needs. We covered 8-pound travel units through a multi-night unit so you do not overbuy or underbuy.
Frequently Asked Questions
Before You Buy
A CPAP battery is one use of a power station, and the sizing logic overlaps with general backup:
- What size power station do I need. The full sizing method for any load, not just a CPAP.
- Best portable power stations. The general home-backup roundup if you also want to run a fridge and lights.
- Jackery vs EcoFlow. If you are choosing between the two brands featured here.
If the CPAP is only one of several things you need to keep running in an outage, size for the whole load, not just the machine.
Bottom Line
For most people who want reliable CPAP backup, the EcoFlow RIVER 2 Max is the right size: it covers a full humidifier-on night or close to two dry nights, recharges fast, and is not too heavy to move. If you need multiple nights or refuse to give up the humidifier, the DELTA 3 gives you the larger capacity. For travel, the Jackery 300 Plus and Anker C300 are light enough to fly with and cover a dry night, with the Bluetti EB3A as the budget weekend option.
Whatever you choose, use a power path your CPAP manufacturer accepts, turn the humidifier off to stretch your nights, and use the DC input if your machine supports it. Those three habits matter more than buying a bigger battery.
