Guide

CPAP on DC vs AC from a power station

Portable power station powering a cooler beside a tent at a forest campsite

Running a CPAP from a power station's 12 V port with the maker's DC cord skips the station's inverter, so it usually lasts longer than the AC estimates on this site.

Medical safety notice: Will It Run? gives general power estimates only, not medical advice. Power draw varies by model, settings, pressure, humidifier and altitude. Before relying on any battery, power station, inverter or generator for a medical device, confirm approved power sources with the device manufacturer and your doctor or equipment supplier, and test your setup before an emergency. Never change prescribed settings to extend battery life. If your therapy is life-sustaining, keep the backup your supplier provides, register with your utility's medical-needs program, and have an evacuation plan. Run generators outdoors only, at least 20 ft from windows and doors, because of carbon monoxide risk. In an emergency, call 911.

Willrun's CPAP runtimes now show AC and DC separately (see the methodology). AC nights take off 15% for conversion loss and also add about 15 W for the inverter's own draw: BLUETTI counts about 15 W of self-consumption in its AC180 runtime formula, and an owner test measured about 17.5 W idle on a DELTA 3 Plus. DC nights skip the inverter and are a best case: manufacturers do not publish a separate DC consumption figure, so we use the same machine watts and the same 15% allowance. With the humidifier off the gap is large. On a 1,024 Wh station an AirSense 11 (7 W) gets about 4.9 nights on AC versus up to 15.5 on DC. With a heated tube (55 W) it narrows to about 1.6 versus 2.0. The CPAP power station guide shows nights both ways for each pick, plus the 12 V current each ResMed DC converter needs.

What the manuals say

Philips says to use only a Philips Respironics DC power cord and battery adapter cable, and not to run the device from a vehicle battery while the engine is running (DreamStation manual).
The DreamStation 2 manual says its battery pack does not support humidification, and an 80 W supply is needed for the humidifier (DreamStation 2 manual).
Use the DC converter made for your exact model. Ask your equipment supplier.

ResMed DC converters on Amazon Philips DC cords on AmazonAs an Amazon Associate we earn from qualifying purchases.

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Questions

Is DC better for a CPAP on a power station?

Usually yes, because it skips the inverter's conversion loss and its own idle draw (about 15 W on a BLUETTI AC180). Use only the manufacturer DC cord or converter for your model.