Why CPAPs Are Different From Every Other Device
Phone, camera, laptop — they all draw power in short bursts with idle time in between. A CPAP runs continuously for 7–8 hours. That changes the sizing equation completely. With a phone, a rough mAh estimate is good enough. With a CPAP, you need actual watt-hours, because the math doesn't forgive mistakes.
The confusion starts with the specs. CPAP manufacturers list a "power consumption" figure in watts — but that number varies depending on pressure setting, whether the heated humidifier and heated hose are on, and the ambient room temperature. A ResMed AirSense 10 draws 53W at maximum pressure with everything enabled, but drops to 30W at typical therapeutic settings. The specification sheet figure doesn't represent a real night. Your actual usage probably falls somewhere in between — but closer to the high end if you use a heated hose in a cold room.
Before buying any power bank for CPAP use, you need a realistic watt-hour target. Without that, you're guessing — and the power bank that looks adequate on paper will leave you waking up at 3am to a machine that's shut down.
CPAP Power Draw: What the Numbers Actually Mean
The CPAP itself is a small blower motor. It's the heated humidifier and heated hose that transform a CPAP from a low-draw device into something that needs serious battery capacity.
- CPAP motor only (no humidifier, no heated hose): 30–45W depending on pressure setting. Most users run at 8–12 cmH2O, drawing 30–35W.
- With standard heated humidifier (most common setup): adds 20–35W. The humidifier heater plate draws 25–50W on its own, though it cycles on and off. Net addition is roughly 20–30W average.
- With heated hose (ClimateLine or similar): adds 10–18W. The hose has a resistance wire that runs continuously.
- Full climate control mode (auto temp + humidity): draws 60–80W peak. This is the maximum-draw scenario.
For a typical user at 10 cmH2O with a heated humidifier on a medium setting, plan on 50–60W average. For a cold bedroom with the heated hose running full, 65–75W is realistic. The difference between these two scenarios is the difference between a power bank lasting 4 hours and lasting 2.5.
The Power Bank Capacity Math (Finally Explained Clearly)
Every power bank is rated in milliamp-hours (mAh) at a cell voltage of 3.7V. Your CPAP or CPAP power adapter delivers power at 5V, 9V, 12V, or 24V depending on the model. The mismatch is where the confusion starts — and where you lose capacity before the power ever reaches your machine.
Step 1: Convert labeled mAh to watt-hours at the cell level.
Wh (cell) = (mAh × 3.7V) ÷ 1000
A 26,800mAh power bank: (26,800 × 3.7) ÷ 1000 = 99.2Wh at the cells. A 20,000mAh bank: 74Wh. A 10,000mAh bank: 37Wh.
Step 2: Account for voltage conversion loss.
Power banks convert from 3.7V up to the output voltage using a boost converter. Efficiency runs 85–92% depending on the quality of the power bank and the load. At 90% efficiency: a 99.2Wh cell-capacity bank delivers ~89Wh at the USB output. This is before the CPAP's own power adapter converts USB voltage to whatever the machine needs internally — another 5–10% loss.
Step 3: Calculate usable runtime.
Runtime (hours) = Usable Wh ÷ CPAP watt draw
A 26,800mAh (99.2Wh cell) power bank at 90% efficiency delivers ~89Wh. At a CPAP draw of 55W: 89 ÷ 55 = 1.6 hours. Not a typo. At a CPAP draw of 30W: 89 ÷ 30 = 2.9 hours. Still not a full night.
The standard 26,800mAh power bank that looks generously sized will run a CPAP for 1.5–3 hours depending on settings. That's useful for a nap, a power outage, or a camping night where you have grid access the next morning. It's not useful for all-night operation away from power.
The Airline Problem: Why 100Wh Is the Real Ceiling
FAA and most international aviation authorities limit spare lithium batteries to 100Wh without airline approval. Most power banks with lithium cells sit in the 37–100Wh range. The practical result: the largest power bank you can carry onto a plane without special permission delivers roughly 89Wh usable after conversion losses — and that runs a CPAP for under 3 hours at typical settings.
Some CPAP manufacturers produce batteries specifically designed to be FAA-compliant. The ResMed AirCube Battery is 94Wh. The Medistrom Poweraddict is 94Wh. These are designed to work with specific CPAP models and include the correct barrel connectors and voltage profiles. They don't require USB-C PD negotiation and don't suffer from the voltage conversion losses of a generic power bank — because they connect directly at the battery voltage level. A 94Wh CPAP-specific battery runs a CPAP for roughly 6–7 hours at typical draw (94 × 0.90 efficiency ÷ 15W motor-only draw = 5.6 hours; with humidifier at 50W average = 1.7 hours). The point isn't raw Wh — it's direct connection to the machine's native voltage.
If you're flying with a CPAP and need battery backup, the FAA-compliant CPAP batteries exist precisely for this use case. General-purpose power banks aren't the right tool for air travel CPAP backup.
Portable Power Stations: The Only Real All-Night Option
For consistent all-night CPAP operation off-grid, you need a portable power station — a large lithium battery with AC output, not a USB power bank. The power station's AC inverter runs your CPAP's DC power adapter at full efficiency. The capacity math changes completely because there's no USB voltage conversion step.
For an 8-hour night at 55W average CPAP draw, you need 440Wh of capacity minimum (accounting for 90% inverter efficiency: 440 × 0.90 = 396Wh delivered). The practical minimum for reliable all-night operation is 500Wh. At 500Wh: 500 × 0.90 ÷ 55W = 8.2 hours — enough for a full night with margin.
Jackery Explorer 300 (293Wh): Not enough. Runs a CPAP for roughly 4–5 hours at typical settings — useful for naps or backup, not full nights.
Jackery Explorer 500 (518Wh): Minimum viable all-night option. At 55W average, 518 × 0.90 ÷ 55 = 8.5 hours. Works for most users at sea level in a temperate bedroom. At 65W with heated hose: 518 × 0.90 ÷ 65 = 7.2 hours. Acceptable but tight.
Jackery Explorer 1000 (1,002Wh): Comfortable margin for all-night plus phone charging, a light, and camera battery charging. At 55W, 1002 × 0.90 ÷ 55 = 16.4 hours — two full nights without solar assist.
BioLite BaseCharge 1500 (1,522Wh): For multi-night off-grid use — camping, overlanding, extended power outages. Handles CPAP plus a small fridge if needed.
The key distinction from USB power banks: portable power stations with AC output don't have the USB voltage conversion tax. A 518Wh station delivers roughly 466Wh to the CPAP's DC adapter, versus the same 518Wh cell capacity in a USB power bank delivering ~350Wh after USB boost conversion. The power station is more efficient for AC-device CPAP operation specifically because it skips the USB conversion stage entirely.
USB-C PD CPAPs: A Different Equation
Some newer CPAPs — ResMed AirSense 11, for example — support USB-C Power Delivery charging. This changes the math because USB-C PD has a defined voltage negotiation protocol (9V/3A = 27W, 15V/3A = 45W, 20V/3A = 60W). The CPAP will draw up to its PD request limit, and the power bank must support the required PD profile.
With USB-C PD, the conversion loss is different from traditional barrel-jack DC adapters. The USB-C PD controller in the power bank converts 3.7V cell voltage to the negotiated PD voltage (9V, 15V, or 20V) at 90–95% efficiency. Then the CPAP's internal AC/DC converter takes the DC input and converts it again to the voltages needed by the motor and humidifier — another 5–10% loss. Total conversion path: 3.7V cell → USB PD output (90%) → CPAP internal conversion (90%) = ~81% end-to-end efficiency.
The practical runtime for a USB-C PD CPAP on a power bank: Wh (cell) × 0.81 ÷ CPAP watt draw. A 99.2Wh cell-capacity bank: 99.2 × 0.81 = 80.3Wh delivered to the CPAP. At 55W: 80.3 ÷ 55 = 1.46 hours. At 30W (no humidifier): 80.3 ÷ 30 = 2.7 hours. Still not a full night.
Check your CPAP's manual before assuming USB-C PD will work reliably. Some CPAPs that have a USB-C port only use it for software updates, not for powering therapy. Others require a specific PD profile that not all power banks support. The ResMed AirSense 11 USB-C PD is confirmed at 9V/3A for data-only use in some firmware versions — confirm before relying on it.
Solar Augmentation: Extending Runtime in the Field
For camping or off-grid use, solar panels can extend CPAP runtime by recharging the battery during the day. The practical solar input for a 50W panel in good sun is 40–45W. If your CPAP draws 55W and runs 8 hours (440Wh per night), a 50W solar panel charging during 8 daylight hours delivers roughly 320Wh of recharge. Net daily deficit at 55W: 440 - 320 = 120Wh. Over two nights you'd accumulate a 240Wh deficit — enough to drain a 500Wh station by morning of day three.
The realistic solar + battery setup for multi-night off-grid CPAP use requires a panel rated at 80–100W and a station of at least 1,000Wh. Even then, weather and panel angle reduce output unpredictably. The math is tight enough that solar CPAP augmentation is only practical if you have significant capacity headroom and accept that cloudy days are charging deficit days.
For a detailed breakdown of how solar panels compare to power banks for field use, see our solar chargers vs power banks field guide.
The Calculation Checklist: Sizing Your CPAP Battery
Before buying anything, work through these four numbers:
1. Find your CPAP's watt draw. Check the specification sheet — it will list a watts figure, usually under "power consumption." If it gives amps and volts instead, multiply: watts = amps × volts. Typical range: 30–80W.
2. Estimate your real draw. If you always use the heated humidifier and hose, use the higher number. If you sometimes run without them (summer, humid climate), the lower number is your baseline. Calculate both scenarios.
3. Decide your required runtime. Full night (7–9 hours) or backup/nap (2–3 hours)? This determines whether you need a power station or a power bank.
4. Apply the conversion formula. For USB power banks: Runtime (hours) = (labeled mAh × 3.7V ÷ 1000 × 0.85) ÷ CPAP watts. For power stations: Runtime = (Wh capacity × 0.90) ÷ CPAP watts.
Example: 26,800mAh USB bank at 55W CPAP draw: (26.8 × 3.7 × 0.85) ÷ 55 = 84.2 ÷ 55 = 1.53 hours. If that disappoints you, it's because the math is real.
What We Recommend for Specific Use Cases
Power outage backup (CPAP-specific battery): Medistrom Poweraddict (94Wh, FAA compliant) is purpose-built for this — it connects directly to ResMed and other CPAP models, includes the correct barrel connector, and has an integrated UPS function that switches over without interrupting therapy. Price: ~$180. The wrong answer: a generic USB power bank, which won't connect without a USB-C PD adapter that your CPAP may not accept for therapy power.
Car camping / drive-in cinema / one-night off-grid: A 500–600Wh portable power station is the right tool. The Jackery Explorer 500 at $499 delivers 518Wh and runs most CPAPs for a full night. It recharges from a car cigarette lighter socket in about 7–8 hours if you're driving during the day. Budget option: a 300Wh station covers a 4–5 hour night if your CPAP draw is on the lower end and you don't use a heated hose.
Multi-night off-grid / camping: 1,000Wh+ portable power station minimum, ideally paired with an 80–100W solar panel. The Jackery Explorer 1000 at ~$1,000 handles two full nights. Add a 100W solar panel (~$150) and you extend indefinitely in decent weather. See our solar panels vs power banks field test for real-world solar charging data.
Air travel with CPAP backup: Buy the FAA-compliant CPAP battery designed for your specific machine. Don't try to substitute a power bank. Airlines require spare lithium batteries to be carried in carry-on, not checked luggage — the battery must also be protected against short circuit. Most CPAP-specific batteries are tested and approved for this use. Confirm with your airline before flying.
Budget CPAP backup under $100: If your CPAP has a USB-C PD port that accepts power delivery for therapy (check the manual — many don't), a 65W+ USB PD power bank like the Nitecore NFZ100 or Shargeek 170 delivers 1.5–2 hours of runtime at typical CPAP draw. That's useful for an afternoon nap or a short power outage while you locate your primary backup. If your CPAP doesn't support USB-C PD for therapy, this won't work.
The Bottom Line on CPAP Power Math
CPAPs draw more than most people expect, and power banks deliver less than their labels suggest. The 26,800mAh power bank that charges your phone five times will run your CPAP for 90–180 minutes. That's useful for specific scenarios — naps, short outages, brief off-grid stops — but it won't get you through a night. If all-night off-grid CPAP operation is the goal, budget for a 500Wh+ portable power station. If you're flying, buy a CPAP-specific FAA-compliant battery. The math doesn't lie: wrong battery type for the use case ends in a 3am wake-up call.
For a broader view of how power banks perform under real field conditions across different devices and capacities, see our camping power bank real-capacity analysis.