What Is a CPAP Backup Battery? Everything You Need to Know
A CPAP backup battery is a portable lithium power source designed to run your CPAP or BiPAP machine when wall power isn't available — during power outages, camping trips, air travel, or off-grid living. With the right battery, you can sleep through the night without missing a single breath of therapy.
How CPAP backup batteries work
Most modern CPAPs run on 12V or 24V DC power. Your wall adapter converts household AC power to DC. A backup battery skips the wall entirely — it stores DC energy in lithium-ion or lithium-iron-phosphate (LiFePO4) cells and feeds it directly to your CPAP through a DC output cable or a built-in inverter.
DC-direct batteries are the most efficient option. They connect straight to your CPAP's DC input port, avoiding the energy loss of converting DC → AC → DC. This means more runtime per charge and a smaller, lighter battery.
Portable power stations (like Jackery, EcoFlow, Bluetti) use a built-in AC inverter. They're more versatile — you can charge phones, laptops, and other gear — but they're heavier and waste 10–15% of capacity in the DC-to-AC conversion.
Key specs to understand
Battery shopping is confusing if you don't know what the numbers mean. Here are the only specs that matter:
Watt-hours (Wh)
The total energy stored. A 150 Wh battery running a 30 W CPAP lasts roughly 5 hours (150 ÷ 30 = 5). This is the single most important number.
Voltage (V)
Must match your CPAP. Most use 12V or 24V DC. ResMed AirSense 10/11 uses 24V; many others use 12V. Wrong voltage = won't work or could damage your machine.
Battery chemistry
LiFePO4 lasts 2,000+ cycles and is safer. Li-ion is lighter per Wh but degrades faster (~500 cycles). For nightly CPAP use, LiFePO4 offers better long-term value.
FAA limit (100 Wh)
Airlines allow batteries under 100 Wh in carry-on without approval. 100–160 Wh requires airline approval. Over 160 Wh is banned on flights.
How much power does a CPAP actually use?
This varies significantly based on your pressure settings and whether you use a heated humidifier or heated tube:
| Configuration | Typical draw | Notes |
|---|---|---|
| CPAP only (no humidifier) | 15–30 W | Best battery runtime; fine for most travel |
| CPAP + heated humidifier | 40–60 W | Roughly doubles power consumption |
| CPAP + humidifier + heated tube | 50–80 W | Maximum comfort; needs a bigger battery |
| BiPAP / auto-titrating | 30–90 W | Higher pressures = more power; check your model |
For a detailed walkthrough on calculating your exact needs, see our CPAP battery sizing guide.
Types of CPAP backup batteries
Purpose-built CPAP batteries
Compact, lightweight, designed specifically for CPAP DC power. Examples: Medistrom Pilot-24 Lite, Freedom V² CPAP Battery. Typically 97–99 Wh to stay under FAA limits.
Portable power stations
Multi-purpose batteries with AC outlets, USB, and 12V ports. Brands like Jackery, EcoFlow, Bluetti. Heavier but can power multiple devices. Great for camping and home backup.
DIY LiFePO4 packs
Custom-assembled battery packs using LiFePO4 cells. Maximum value per watt-hour but requires electrical knowledge. Not FAA-approved for air travel.
Car/RV batteries + inverter
Use your vehicle's 12V system with a cigarette lighter adapter or DC-DC converter. Works for car camping but drains your vehicle battery — a battery isolator is recommended.
CPAP brand compatibility
Not every battery works with every CPAP. Voltage, connector type, and power delivery all vary by brand:
| CPAP Brand / Model | Input voltage | DC connector | Compatible batteries |
|---|---|---|---|
| ResMed AirSense 10 | 24V DC | 3-pin proprietary | Medistrom Pilot-24 Lite, Freedom V² |
| ResMed AirSense 11 | 24V DC | USB-C PD (65W+) | Any 65W+ USB-C PD battery |
| ResMed AirMini | 24V DC | Micro USB-shaped | Medistrom Pilot-24 Lite, purpose-built |
| Philips DreamStation 2 | 12V DC | Barrel connector | Most 12V batteries + correct cable |
For a complete compatibility matrix, see our CPAP battery compatibility guide.
Flying with a CPAP battery
CPAP machines are FAA-approved medical devices and don't count toward carry-on limits. But the battery has separate rules:
- Under 100 Wh: Allowed in carry-on. No airline approval needed. Most purpose-built CPAP batteries are designed to stay under this limit.
- 100–160 Wh: Allowed in carry-on with airline approval. Call ahead. Some larger portable power stations fall in this range.
- Over 160 Wh: Banned from all commercial flights. This rules out most large portable power stations.
- Checked bags: Lithium batteries are never allowed in checked luggage. Always carry on.
For airline-specific rules and packing tips, see our CPAP battery travel checklist.
How long will a battery run my CPAP?
The formula is simple: Runtime (hours) = Battery Wh ÷ CPAP wattage. But real-world numbers are always lower due to conversion losses and variable pressure:
| Battery size | CPAP only (25W) | CPAP + humidifier (50W) | Full setup (70W) |
|---|---|---|---|
| 97 Wh (travel) | ~3.5 hrs | ~1.7 hrs | ~1.2 hrs |
| 240 Wh (mid-range) | ~8.5 hrs | ~4.3 hrs | ~3 hrs |
| 500 Wh (large) | ~18 hrs | ~9 hrs | ~6.3 hrs |
| 1,000 Wh (home backup) | ~36 hrs | ~18 hrs | ~12.5 hrs |
These are estimates using DC-direct power. AC inverter setups lose 10–15% efficiency. For exact calculations, see our battery sizing guide.
Frequently asked questions
Can I use any portable battery with my CPAP?
Not safely. You need the correct voltage (12V or 24V depending on your CPAP model) and a compatible connector cable. Using an AC power station with the stock wall charger works universally but wastes 10–15% of battery capacity. A DC-direct connection is more efficient but requires model-specific cables.
Do I need to turn off my humidifier when using a battery?
You don't have to, but it roughly doubles your power consumption. If battery runtime is a concern (like air travel or a small battery), turning off the heated humidifier and heated tube is the quickest way to extend runtime. Many people use an HME (heat-moisture exchanger) filter as a no-power alternative.
Will my CPAP battery charge while I'm using it?
Some batteries support pass-through charging (charge and discharge simultaneously), but this generates extra heat and can reduce battery lifespan. Most purpose-built CPAP batteries recommend charging during the day and running the CPAP at night.
How many nights can I get from one charge?
That depends entirely on your CPAP's power draw and the battery's capacity. A 240 Wh battery with a CPAP drawing 25 W (no humidifier) can last about 8–9 hours — roughly one full night. For multiple nights, you either need a larger battery, solar charging, or the ability to recharge between nights.
Are CPAP batteries covered by insurance?
Generally no. Most insurance plans don't cover portable batteries. However, some DME suppliers offer them, and HSA/FSA funds may be used with a letter of medical necessity from your doctor. Check with your insurance provider.
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