Can you use a CPAP machine in an RV when boondocking? The answer is absolutely yes. How to do that is what we get into here and, be forewarned, it may take a tiny bit of calculation to determine how to make this work for you. But we have answers on how to use your CPAP machine in your RV. 

CPAP breathing machines are very, very common nowadays with many people reporting that they use them. It is no longer a surprise at all to see that RV manufacturers have placed 110vac plug outlets by the bed in recognition of the popularity of these machines. 

With more people demanding such amenities, there are also battery kits for a lot of the popular CPAP machines depending on how much current they use. Before you move forward you might determine if a battery kit is available for your particular machine or, if you’re looking at new machines, if they have a battery option for it.

Even if a proprietary battery isn’t an option there are still plenty of other ways to use a CPAP even miles away from the power grid.  

Your first step is to review your CPAP machine to discover how much power it draws. Most CPAP machines run off an AC current, but some have a built-in plug for a DC current.

How to find how much power your CPAP machine needs

Here’s the math part. To figure out how much power your CPAP needs you’ll have to see how many watts it consumes. This should be listed on a label on the machine. 

Electrical devices like CPAP machines, toasters and blenders and just about any other household appliance is generally measured in watts. But batteries are sold by the amp-hour, or how many amps they can deliver. It’s pretty easy to figure this number out. 

Watts/volts=amp draw. You’re using the 12 volt system in your RV or battery (even though it’s ultimately being converted to 110vac) so for a 30-watt machine, the calculation is

• 30 watts/12 volts = 2.75 amp draw.

For a 60-watt machine, the calculation is

• 60 watts/12 volts = 5.5 amp draw

The battery in any RV is measured by how many total amps it delivers. Your next step is to see how many amp-hours you need to run the CPAP; essentially how much power it will consume during a use. Because you should use a CPAP for the entire time you’re asleep, you should calculate how many hours you’ll be asleep. So assuming you have a machine that consumes 60 watts, the calculation for amp-hours is:

• 5.5 amps for 8 hours of sleep = 44 amps from the battery

• 5.5 amps for 10 hours of sleep = 55 amps from the battery

The battery in your RV is a 12 volt battery but if you’re plugging your CPAP machine into a standard household electrical outlet, which is typical, then you’re also going to have to convert that 12 volt current into 110vac household current. That’s the job of an inverter.

More and more newer RVs are coming with inverters either as standard or optional equipment. However, also know that an inverter consumes some power to operate and a built-in whole-RV inverter may take 10-15% additional power to provide that household 110vac current. 

So to use a CPAP on a battery all night, you’ll need 48.4 amps for 8 hours of sleep.

What about RV batteries

Most travel trailers come with one lead acid battery and these typically are labeled with about 80-150 amp hours of reserve power. Based on our earlier calculation you’ll need 55 amp hours so you should be good, even with the additional 10-15% for the inverter, right? 

Sort of. 

Lead acid batteries are only able to deliver 50% of their energy before diminishing to the point that they can be damaged so that 150 amp-hour battery is really only good for about half of what it’s rated for. This is why a lot of people use two golf cart style batteries - these reportedly deliver over 200 amp-hours so these two batteries and an inverter should be sufficient. 

Depending on your RV, you may have a motorhome with six or more household batteries which is a lot of reserve juice. 

Don’t forget there are other things using those batteries as well such as the furnace fan and all the little control boards in the various systems (hear our podcast on RV electricity explained) so you’ll want to have reserve capacity. 

You can use solar to recharge these batteries in the day we have a podcast episode about RV solar as well. 

Other power options

Another option if your RV doesn’t have an inverter or if you don’t want to use the whole-RV inverter is to get a smaller inverter and run wires to a power source, for example to the fuse box if there’s an extra spot there. You could wire up a 12volt “cigarette lighter” socket and plug a small inverter into that, for example. 

Generally speaking, the smaller the inverter the less power it consumes when converting 12volt to 110vac. 

Another option is a portable battery pack. As high-performance batteries become more common there are now devices known as “solar generators” that can also provide power. 

We have long been a fan of Lion Energy and they have the Lion Safari LT that may be sufficient for your needs and the Safari ME that absolutely would cover a CPAP over several days use. I have also seen people talk about the Jackery Solar Generator as being a good solution to this. 

You can read a complete review of the Jackery 1500 here.

A word of caution - even though these are called solar generators they do not generate power. They are simply a large battery and inverter built into one box that you have to charge, whether that be with a solar panel or traditional generator or wall outlet. They do not generate power, they only store and deliver it. 

In summary

There are a lot of ways you can use a CPAP overnight while boondocking. Knowing the specific electrical demands of your unit is going to be your first step but it is absolutely possible to do this today and will continue to get easier as battery technology gets better over time.