Cpap for tent dweller

[Trishdonner]

Hello. I am a Cpap user and soon to become a tent dweller. I am looking forward to boon docking, except I cannot sleep without my Cpap, and if I tried, it would be very dangerous for me. For those of you who don't know, a Cpap is  medical appliance that helps me breath when I am sleeping. Without it, I stop breathing and run a high risk of dying from heart disease or stroke. It runs on household electric current. 

Here's my question: what is the most efficient way to run it off grid?  I know that batteries are sold by the manufactures, but if I could afford that, I would not be sleeping in a tent. Anyone have any advice or ideas?

 

[Trebor English]

Do you know how much it uses?  Preferably, do you have a Kill A Watt and what does it say?  What is the make and model?  Maybe someone else here knows how much it uses.  Some CPAPs have a humidifier option that can use a lot of power.  Does yours have a humidifier and do you use it?  Sometimes the manufacturer's label has information accurate enough to be useful.

Once you know the needs of the machine it's a matter of determining the battery and inverter size needed and then how to put that much back into the battery.  

Just a guess but you might be able to use a $100 battery, a $100 solar panel, a $10 PWM controller and a $20 400 watt inverter.

 

[GypsySpirit]

I haven't tried it, but a friend used this setup and said it worked fine with his ResMed. appx 25% battery drain per night while using the humidifier: Total cost $255 for a 35 Ah system powered by a 50 W solar panel. Cost does not include the Resmed DC adapter, 700W inverter, which I already have, and wire to connect battery to controller.
$85 Renogy 50 Watts 12 Volts Monocrystalline Solar Panel
$23 One Pair of 10Ft. 10AWG Adaptor Kit
$64 ML35-12 - 12V 35AH U1 Deep Cycle AGM Solar Battery
$21 HQST 20 Amp PWM Smart Solar Charge Controller
$13 Attwood Corporation 9082-1 Small Battery Box
$15 Automotive DC Power Outlet Extension w/On-Off Switch
$10 Small Tilt Mount For Renogy 10W/20W/30W Solar Panels

 

[Trishdonner]

It is a ResMed AirSense 10 Auto Set. I do use the humidifier, and I'm not sure it can be turned off. I imagine I can google it to find the watts if I need to.

 

[Trishdonner]

I haven't tried it, but a friend used this setup and said it worked fine with his ResMed.  appx 25% battery drain per night while using the humidifier:   Total cost $255 for a 35 Ah system powered by a 50 W solar panel. Cost does not include the Resmed DC adapter, 700W inverter, which I already have, and wire to connect battery to controller.
$85 Renogy 50 Watts 12 Volts Monocrystalline Solar Panel
$23 One Pair of 10Ft. 10AWG Adaptor Kit
$64 ML35-12 - 12V 35AH U1 Deep Cycle AGM Solar Battery
$21 HQST 20 Amp PWM Smart Solar Charge Controller
$13 Attwood Corporation 9082-1 Small Battery Box
$15 Automotive DC Power Outlet Extension w/On-Off Switch
$10 Small Tilt Mount For Renogy 10W/20W/30W Solar Panels

Could you tell me where to find this equipment?

 

[BigT]

Here's a thread I started a while ago on running CPAP in my minivan ---> https://vanlivingforum.com/showthread.php?tid=11661

Give it a good read and make sure to carefully read the replies from SternWake. He and the knowledge he provided were instrumental in getting my system up and running.

Here's the rub. The AGM battery works well, but it needs to be fully charged regularly or you'll kill it. You can't just use it every night and expect the solar panel to recharge it by the next day...... or even in several days. At some point, depending on the Amp Hour rating of the battery, you're going to need to start the car and give the battery a complete charge. This could take several hours / miles.

I'm running a 75 Amp Hour AGM (that's pretty small), connected to the van's alternator, with a 190 Watt panel, and I can't run the CPAP indefinitely.
Fortunately I don't have to because I'm not living in my van.

Removing the humidifier will greatly increase the time you can run it off the car.

I run the Respironics 560P. It's 12 Volts so it's easy to convert to automotive use with a $25 adapter you plug into your Acc outlet (lighter).

 

[Trebor English]

The ResMed AirSense 10 Auto Set pdf file indicates that the device works from 24 volts.  There is apparently a 90 watt 120 to 24 volt power supply that delivers 3.75 amps with a typical load of 53 watts.  There are power supplies on the internet that convert 12 volts to 24.  That would be more efficient than using the standard power supply with a 12 volt to 120 volt inverter.  

The easy way would be to get a small inverter, 200 to 400 watt, and just plug the CPAP into it.  An actual load about 60 watts is about 6 amps, 48 amp hours over an 8 hour period.  A 100 amp hour battery and 100 watt panel would work with sunny days.

The more difficult approach would be to get a 12 to 24 converter.  They are about $15.  The internet says "Conversion efficiency: up to 90%" so  8 hours at 2.25 amps of 24 volts (54 watts) would be at least 5 amps, 40 amp hours.  Again, 100 amp hour battery and 100 watt panel would be good on sunny days but with a little bit more margin.

This is a hefty load like a fridge.  200 watts of solar and a pair of golf cart batteries would be able to survive a rainy day.  My recommendation is to avoid the marginal 100 amp hour 100 watt solution if the bigger system is affordable.  I think the 12 to 24 converter is a better solution but only if the technology to connect a different power supply is ok.

Tent, non-van, use would make tilting the panel easy.  That would help.  

The 53 watt typical loading might be way off.  Sometimes manufacturers give technical details that are skewed for one reason or another.  A Kill A Watt test of how much electricity you actually use would be very helpful.  Your pressure setting and breathing rate could affect the consumption substantially.

 

[Trebor English]

Or, you could have a 24 volt no conversion loss system.  Get 2 12 volt panels in series, 2 12 volt batteries in series.  Everything is 24 volt.

 

[GypsySpirit]

Could you tell me where to find this equipment?

Everything was purchased from Amazon.  Again, this is what my friend used for a ten day primitive tent camping trip.

Now, I defer to my betters.   Electricity scares me and I am clueless about solar.  I've done a ton of reading up on it, but am more confused than anything.  Please, please read what the more experienced vandwellers are saying.  They know far more about it than I do.

 

[GotSmart]

My 12v system for the CPAP clearly states that you can not use the heater humidifier.

 

[Zizzer_Zazzer_Zuz]

My CPAP and it's emergency back up power pack. This has also turned in to a project power supply among other things. I don't know what I paid for the parts and pieces. Use that other parts list for specifics. This just so you can see how one might look. I am considering the XL popup tent cot and think I could.position the box under the tent cot and run power inside. In a traditional tent you would just pull it inside with you.

Thats a battery box with 12v outlets. It holds a 30ah SLA help in place with stirofoam. When not in use or for transport I can fit the inverter and the A/C charge controler along with all of the wires and cables. Without the battery tender I can substitute the 25' leeds for the solar panel. The panel is a 40watt polycrystaline panel. The solat charge controler is just a cheap PWM job. The battery tender came with some cables and adaptors so I can also charge via car.

The longest test I've run was 4 nights on the battery without recharge and it got to 12.4v. Good enough for me! I did not use the humidafier or the tube heater at all. I much prefer it however I can live without it but I might not live without the assistance breathing.

I forget the brand but 12v chargers for mine were pretty much readaly available for $30-$40.

As for a 12v cord for a CPAP that says not to use the heater would be quistionable in my eyes. I am forgetful and don't realy want to die in a fire.

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[Trishdonner]

My 12v system for the CPAP clearly states that you can not use the heater humidifier.

Yeah, and I don't think I run the machine without the humidifier. My previous machine would let me turn off the heater.

 

[GotSmart]

I bought the cord from the company website.  Resperonics is not about to give bad advice on a brand name product.  

Do your research.  Don't rely on internet advice.

 

[Trishdonner]

I am not a techy person. I thank all of you for your help and your advice on the subject of powering my cpap. That being said, HELP! I am confused as ever.

• What kind of solar panel should I get?
• What is an inverter, and how do I use it?
• I found 50 Watt sunpower 18v 12v lightweight, bendable, semi flexible solar panel charger on Amazon for 85.49. Is this a good one? Should I get 4 of them if I choose this rout?
• What about golf cart batteries? How do they work? Do I use them with the solar panels?
• How do I use any of this?

True confession: Technology makes me hyperventilate because I don't understand it. One thing for sure, not having reliable power source for my cpap complicates boondocking and if I can't resolve the issue I will have to continue to struggle in the city like I've been doing.

 

[Cammalu]

Trish, are you sure your machine doesn't come apart in two pieces? Can you post a pic of it?

Where are you? Perhaps there is another solar savy board member that is close by or maybe you can travel a bit for help.

 

[Trishdonner]

Trish, are you sure your machine doesn't come apart in two pieces?  Can you post a pic of it?

Where are you?  Perhaps there is another solar savy board member that is close by or maybe you can travel a bit for help.

I'm in North Highlands (Sacramento), California. I won't be ready to work on this for a few months. I'm in the planning stage now, as I know I am about to loose my so called home. I just need a plan. I need to know what equipment to get, where to get it, and how much it will cost.

 

[Cammalu]

Trish, what if u turn the humidifier down to one and just don't put water in it?

Renogy is in southern CA and many people use them for solar needs. If you explain what need to power they will be able to tell you everything. I have a renogy solar setup and I'm well please with it.


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[GotSmart]

you need to contact Resed direct, and ask about the power use information for your unit.  There is a 12 volt cable available for your unit

 

[sometimesido]

I use the exact same one so I did some digging.

Here's some info(vague) probably need to call.
http://www.resmed.com/us/en/consume...intenance/traveling-with-your-equipment.html#

Also found online by searching airsense 10 DC converter, but they go for around $100...

 

[Zizzer_Zazzer_Zuz]

A couple of questions that should probably answered.

Aside from your CPAP what are you trying to power?

About how many nights do you want to power the CPAP without recharging the.battery?

What sort of budget do you have?

Some simple definitions.

Solar panels come in many variaties and sizes. Relax about the details here for a little while.

The charge controller sits between the panels and the batterry/batteries.

So far all of this electricity is in Direct Current, DC.

At home your wall outlets are Alternating Current.

To convert DC to AC you must use an inverter. This conversion creates loss.

The thing is that your CPAP itself runs on DC. The power brick part of the power cord converts AC to DC so using a 12v DC power cord just makes sense.

Take a look at the bottom of the CPAP there should be a sticker that describes the power usage. It may be on the power brick or printed in the plasric where the power cord plugs in.

Post pictures of those things.

SOME 12v outlets are not built for the sort of continous draw the CPAP uses and so you will want to be careful about that.

Water in the humidifier even if it's turned off helps.

All.CPAPs can have the heater and humidifier turned off. Unless you are boondocking, expecting several days of bad weather, or don't have any other way to charge the battery you will most likely be able to use the humidifier at least on low settings.

The biggest question is how will YOU use this set up?

I started with a 32aH battery, a battery box, a decent battery charger, and a small inverter. I wanted a battery back up for my CPAP in case of power outage. That has expanded a bit but that osbstill the number function for that battery and the pieces with it.

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