Medical-device outage planning
How long will a 500Wh power station run a CPAP?
CPAP power use varies with pressure, heated humidification, heated tubing and the power adapter. Use the device maker's approved power options and measure your own setup before relying on an outage estimate.
Backup power runtime
Estimate steady-load runtime after inverter losses and a safety reserve.
Runtime = capacity × efficiency × usable battery share ÷ average load. Motor surge, temperature, battery age and device cycling can change real-world runtime.
What changes the answer?
Heated features can change runtime substantially
Humidifier heaters and heated tubing can draw more power than the blower alone. Calculate the exact configuration you intend to use during an outage, including the manufacturer-approved adapter.
Keep a reserve and a second plan
Do not plan to use every advertised watt-hour. Battery age, temperature and conversion losses reduce usable energy, and a critical medical device needs a backup plan if charging or the power station fails.
Test the complete setup before an emergency
Confirm that the power station provides stable output, does not shut off at a low load and supports the device for a full representative night. Follow the CPAP manufacturer's instructions.
Use this result as a planning range
This electrical estimate is not medical advice. If therapy is medically necessary, discuss outage planning with your clinician and device provider and follow FDA emergency guidance.
Review the formulas and public sources in our methodology.
Official references
- Analyzing household electricity loadsU.S. Department of Energy
- Food safety during a power outageFoodSafety.gov
- Generator and carbon-monoxide safetyU.S. Consumer Product Safety Commission
- Medical devices and emergency power planningU.S. Food and Drug Administration