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Power Inverters and C-pap Machines

A future RVer asks....

Will C-pap machines work with power inverters? My husband and I have bought our motorhome and will be RVing fulltime by August of this year. We bought a Fleetwood Flair. We both wear C-pap machines at night and don't want to have to run our generator while traveling or boondocking.

Was wondering if a power inverter connected to a cigarette lighter would work? Or, would we need to run a line to the house battery? Any information would be helpful. Thanks.

Coleen, the RVing editor comments:

I love our solar system and we can do a lot with it. But, it has multiple photovoltaic panels, batteries, an inverter, regulator, etc. It's great to be able to boondock days on end without the need to plug into shore power.

I can certainly see why you'd want to go with a solar system to power your medical devices. I think you need more than just a small power inverter that you can plug into a cigarette lighter, though. One thing that comes to mind is that you may need a pure sine wave inverter and the less costly ones may only be modified sine wave.

Bob knows more about these mechanical and technical things than I do, so let's see what he has to say about it.

Bob comments:

I'm sorry, but I'm not familiar with C-pap machines and their energy requirements. From what I know, the machine helps with breathing while you sleep. I would think this would be important, and something I wouldn't want to trust a cigarette lighter appliance to power.

I would look at the machine and see the actual power usage, then get hold of RV Solar Electric in Scottsdale, AZ, and explain what you want to do and see what they suggest.

You may think about a dedicated battery bank, with an isolator, batteries, and a quality, well built inverter for your medical machines. I would expect to spend possibly $1000.00 or more on a dedicated system. I don't know if insurance would pay for a dedicated system, but I believe it may be tax deductible.

If it is important for your health, I wouldn't trust a "get by, jury rigged, Mickey Mouse" system.

You may look at solar panels and a system for your whole RV. We've had solar for over 20 years and it is truly a godsend.

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Comments for Power Inverters and C-pap Machines

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CPAP in RV's
by: Anonymous

Depending on the brand, I work with Res-Med brand Cpap machines. They are actually 12 volt DC and have a converter to take the 120v from the wall and drop it to 12 volts and condition it to DC.

If you look on the box, if it is on the power cord, it will tell the input and output. If it is 12v DC output, you are half way there with no mods. If it is 12v DC, then all you need to do is look at the amperage and multiply by 10. The average night usage of a cpap is between 6 and 10 hours, so be on the safe side with your batteries. You will be able to use a direct plug into your cigarette lighter, or dedicated power port.

I suggest using a dedicated power port that is tied to the house batteries (deep cycle) verses the starter battery. The car charging system varies widely in its power output while you drive and can go from a low of 9 volts to a high of over 17 volts. That can damage your equipment. It is better to have a stable power source like the deep cycle batteries which will swing between 10.5 volts at a low, to 13.2 volts for a high, except when being charged.

Be sure to put a fuse in the line with a rating just above the cpap needs so that if anything goes awry it will blow the fuse instead of your expensive machine. For instance if it uses .5 amps at 120v, the machine might pull 5 amps on a 12 volt source.

If your machine is a 120v only, absolutely use only a full sine wave inverter. Electric motors, of which your cpap uses, need clean power.

Lastly contact your machines manufacturer and ask the tech department what they recommend.

My ResMed does just fine in my RV.

Our CPAP Experience
by: Lee V.

Maybe not the recommended way to power a
CPAP, but we have powered both of our machines off the same small 140 watt modified sine wave inverter quite a few times over the last 5 years with no problem. We plug it into a cigarette lighter or clip onto the battery terminals using an adaptor, then run an extension cord to a multi-tap adapter or outlet strip.

Most CPAPs can run directly from 12 volts DC, using a power cord, available from a number of suppliers (search online). These bypass the power supply and go directly to the machine, eliminating the need for an inverter. Our Respironics machines use 20 watts or less each (without humidifiers), and don't have a noticeable effect on the battery over night. We even run a "box" fan at the same time during hot weather and still have no battery issues.

Since inverters themselves use battery power to operate, running your machines directly from the battery will use even less power. Note that you can't use a humidifier with a DC-only setup.

We are currently adding solar panels and a pure sine wave inverter to the motorhome, and I haven't decided yet whether to continue powering the CPAPs with an inverter, or install direct DC hookups on each side of the bed. Either way, we can dry camp for extended periods of time and have full use of our machines.

RVing with a CPAP -- You Can Do It!
by: Anonymous

We both use CPAP machines too. We have, in a pinch, used a small inverter (150 watts) with no ill effects.

You can buy 12 volt adapters specifically designed for your machines which plug into the 12 volt outlets (about $25 each). If you don't have outlets in your bedroom, they can be easily installed.

There are also rechargeable battery packs you can purchase ($300+) that are specifically designed for your CPAP if you're afraid your house batteries aren't sufficient.

So....don't worry about it. :)

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