Runtime by power station size: CPAP machine (no humidifier)
| Power station size | Typical runtime | Realistic range |
|---|---|---|
| 300 Wh | 7 h 17 min | 5.1–12.8 h |
| 500 Wh | 12 h 9 min | 8.5–21.3 h |
| 1,000 Wh | 24 h 17 min | 17.0–42.5 h |
| 1,500 Wh | 36 h 26 min | 1.1–2.7 days |
| 2,000 Wh | 2.0 days (49 h) | 1.4–3.5 days |
| 3,000 Wh | 3.0 days (73 h) | 2.1–5.3 days |
Runtime by power station size: CPAP with heated humidifier
| Power station size | Typical runtime | Realistic range |
|---|---|---|
| 300 Wh | 4 h 15 min | 2.8–6.4 h |
| 500 Wh | 7 h 5 min | 4.7–10.6 h |
| 1,000 Wh | 14 h 10 min | 9.4–21.3 h |
| 1,500 Wh | 21 h 15 min | 14.2–31.9 h |
| 2,000 Wh | 28 h 20 min | 18.9–42.5 h |
| 3,000 Wh | 42 h 30 min | 1.2–2.7 days |
If you depend on your CPAP for a serious medical condition, agree a backup-power plan with your doctor or equipment supplier. Use this page for planning, not as medical advice.
The humidifier is the big power user
The blower in a modern CPAP is efficient. The heated humidifier and heated tubing are what drive power use up, especially in a cold bedroom. Turning heat off, or using passive (unheated) humidification, often doubles runtime. Check the power figures in your machine's manual: the brick's rating (often 65–90 W) is a maximum, not what it uses through the night.
Use the DC output if you can
A CPAP's power brick converts AC to DC. If you plug it into a power station's AC outlet, the station first converts its DC battery to AC, and then the brick converts it back. Each step wastes energy, and the station's inverter also draws power just by being switched on.
Most CPAP makers sell a DC power cord or converter for their machines. Running from the station's 12 V car-style socket skips the inverter, which typically adds 10–20% more runtime. Choose "DC / USB" in the calculator to see the difference.
How to work out your own CPAP's usage
- Plug the CPAP into a watt meter (or the power station itself, many show live watts).
- Use it normally for a full night with your usual pressure and humidity settings.
- Divide the Wh used by the hours slept to get your average watts.
Higher pressure settings, a leaky mask and a cold room all raise the number, so measure in conditions like the ones you're planning for.
Sizing for a multi-day outage
Multiply your nightly Wh by the number of nights, then divide by about 0.85 for AC (or 0.9 for DC) to get the station size. For example, 280 Wh a night (35 W × 8 hours) for 3 nights on AC needs about 990 Wh: a 1,000 Wh station is just enough, and a larger one gives a margin. A small folding solar panel can top it up during the day; see the solar recharge calculator.