Powering a CPAP Off Grid

You are packing for a camping trip, a long road journey or a storm season, and your CPAP needs mains power you may not have. A small battery can fill the gap, but only if it matches what your machine really draws. This page walks through measuring that draw, stretching it, and working out how many nights each battery size gives you.

Step two: switch to DC and drop the humidifier

Most of your battery's losses come from converting power. A battery stores DC, and an AC outlet makes it go through an inverter, which wastes some energy. Many CPAP machines run on DC internally, so feeding them DC directly skips that step. Check your machine's manual for the right voltage and cable before plugging anything in.

The heated humidifier is the other big saver. It can use more than the blower itself. Switching it off, or turning the heating down, can stretch a night's energy a long way. In dry climates you may miss it, so try a night at home first. Batteries built for this job, with a DC output for CPAP use, make the direct route simple.

Some machines need a different DC voltage. The X30 and X60 have a DC24V conversion cable for this, so check which voltage your CPAP expects.

Step three: how many nights per battery size

Here is the sum. Divide the battery's watt hours by your nightly watt hours, then leave a margin, since you will not get every watt hour out. As an example only, a machine using 30Wh a night on DC with the humidifier off would get several nights from a 297Wh battery. With the humidifier on and a nightly draw of 80Wh, that drops to about three. Your numbers will differ, so use your own meter reading.

The X30 at 297Wh suits a weekend away or a short outage. It is small enough to sit beside the bed.

The X60 at 614Wh roughly doubles that. It suits longer camping trips, or a household that wants a few nights of outage cover with the humidifier running.

If you mostly need a lightweight option for a laptop and a minimal CPAP setup, the X20 is a 288W, 153.6Wh power bank. It is a smaller store of energy, so it suits a night or two at low draw. It also has an adapter sold separately.

Step one: measure what your CPAP draws

Do not trust the number on the power brick. That figure is the maximum the adapter can supply, and your machine usually pulls far less. Look on the brick or in the manual for the rated watts, then measure the real figure. A plug-in watt meter on the wall socket will show your draw over a full night, with the humidifier and heated tube set as you normally use them. Note the average, not the peak. Multiply the average watts by the hours you sleep and you have the watt hours needed per night.

Pressure matters too. A higher prescription setting makes the blower work harder. Measure at your own settings, not someone else's.

Step four: carrying batteries on a flight

Airlines set their own limits on lithium batteries, and they differ by country and carrier. Common points: spare batteries go in carry-on, not checked luggage, and the limit is based on watt hours. Many airlines accept batteries up to 100Wh without approval, and some allow a larger one with permission. The batteries on this page are all above 100Wh, so none of them is automatically allowed. Ask your airline before you book, and carry any written approval with you.

Many travellers who fly with a CPAP also check whether the machine can be carried as medical equipment. Look at the airline's page on medical devices, and follow their rules.

How to choose

• Work out your nightly watt hours first, with your own meter.
• Pick capacity for the number of nights you need, plus a margin.
• Check that the battery has a DC output your machine can use, and whether you need the DC24V cable.
• If you fly, check the airline's watt hour limit before buying.
• Think about weight and size if you will carry it far.

Questions people ask

Can I run my CPAP from a laptop power bank?

Possibly, if its output and connection match what your machine needs. Check the manual and the battery's specs first.

Is the humidifier really worth turning off?

For battery use, yes, it often makes the biggest difference. Try a night at home to see whether you can sleep comfortably without it.

Do I need a bigger battery for an outage than for camping?

That depends on how long you expect to be without power. Count the nights, then use your measured nightly figure.

Can I charge the battery while I use it?

Check the product's manual. Charging methods and whether it can be used at the same time vary, so follow the instructions for your model.