CPAP(continuous positive airway pressure) therapy is used for people who suffer from sleep apnea. But this should not stop people from traveling. So you must be prepared for emergencies. What if you are stuck in a car for some reason without any backup? Can you use your car battery as an emergency CPAP battery backup? The answer is YES! In case of any emergency, you can use your car battery to power your CPAP machine.

A car battery can be used to power a CPAP machine but you may require some extra accessories like a cigarette lighter to DC port or alligator clips to female cigarette socket extension. If your CPAP uses type C as an input, you can also use alligator clips to type C extension.

As you must be familiar most of these CPAP uses an AC power adapter. So, how to use your car battery to power a CPAP device? Well, you have to purchase some CPAP accessories for this and these accessories are cheap!!!

Firstly, you can power your CPAP using your car’s cigarette port. Just buy a cigarette lighter from amazon. Plug this into your cigarette lighter also know as car outlet port and it’s done! Yes, it is soo simple but there is a big drawback. If your car box is using the same battery for the engine then you need to monitor it as CPAP may consume your battery. This is especially true in case you are turning on the humidifier in the CPAP machine.

DC adapter for Respironics

DC adapter for Respironics

Now let us see how to use the car battery directly to power your CPAP device. For this, you will need Alligator clips to female cigarette socket extension. You can get it on Amazon for around $10. Then couple it with a 12V car adapter to power our CPAP.

Aligator to Female Cigarrete

Some may suggest you use an AC convertor from your car battery before powering your CPAP. But most of the CPAP supports the 12V DC today and I feel since the CAPA adapter again converts your AC back to DC, it’s just a waste of power.

If you use a CPAP device when traveling, consider getting a CPAP power station. It makes your life easier, especially during camping.

How long will a CPAP machine run on a Car Battery?

There are various factors that affect the duration of your CPAP device. But let me try to put it this way.

Assuming you are using a 50W CPAP device (like Resmed Airsense) and your car battery is 70Ah (which is the average US automotive battery capacity), you can expect around 15 hours of CPAP backup duration. If you use the device without humidification or pressure, you can expect even more backup time.

Here is the math,

70Ah car batteries are around 12.5 volts. So, 70 * 12.5 = 875 Wh

This means the car battery can power an 875 W gadget for 1 hour. If the gadget consumes only 8.75W, then it can last for 100 hours. You got the point, right?

CPAP device consumes around 50W on average. So, 875Wh divided by 50W = 17.5 hours of backup

This is based on so many assumptions and hence, it might be different in your case. Either way, try not to overuse the car battery. If you empty it, you can’t get the car started! On the other hand, if you have plenty of fuel, you can probably keep the car running while you use the battery. In that case, you will have a lot more backup time and your battery will recharge. At least, until the car runs out of fuel!

Also, it is better not to use humidifiers if you are on the car battery. That way, your backup duration will be much higher. Emptying up your car battery is the last thing you want to do. In such a case, you might require a jump starter to get the car started.

Hope you found some value in this article. If you have any questions, let me know through the comment section below. Also, share this article with someone who has or planning to purchase a CPAP device.