Cpap and overland?

[jkxranger]

I searched and did not find anything posted about what people use to run their Cpap when out in the trails. I was hoping someone has some real world experience and could me some recommendations.

Thanks in advance for any guidance.

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[Quicksilver]

Interested in this myself. I've seen people run a second battery with a power inverter hooked up to it. I'm considering that route, but maybe other options will be presented here.

 

[Mouflon]

I run my CPAP off of my ArkPak. I set it at the foot of my swag and it runs fine all night. Never leave home without it.


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[slomatt]

Most CPAP manufacturers offer a 12v converter, this is much more efficient than running at 120v off an inverter. Turning off the humidifier and hose heater saves a lot of power and gives you longer battery life.

There are multiple options out there using lithium batteries (check out https://www.cpap.com/cpap-power.php) but these are fairly expensive.

Alternatively you can get a dedicated 12v battery and build your own power supply, something like http://www.blankwhitepage.com/gallery/portable_battery.

The key is to determine how many amps your CPAP draws and how many nights you need to support with out recharging. Using those numbers you can figure out how big of a battery is required. If you post this info I can help with the battery calculations if you want.

 

[1Louder]

I would read the threads in this section and elsewhere: https://www.overlandbound.com/forums/forums/overland-vehicle-gear.122/

From a power perspective a CPAP is no different than a fridge if it can be run off of 12 volt. An ArkPak, GoalZero/Yeti or something similar would work. I will say most of the GoalZero power boxes have small batteries so you will want to check to see how long they will last. The ArkPak allows you to pick what type of battery you want in it. I have seen CPAP's discussed on Expedition Portal as well. As Slomat mentioned power is power. You need to know more details about your machine.

If you basecamp a lot then get solar to keep your battery(s) happy.

 

[Quicksilver]

The key is to determine how many amps your CPAP draws and how many nights you need to support with out recharging. Using those numbers you can figure out how big of a battery is required. If you post this info I can help with the battery calculations if you want.

Is this what you need?

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[1Louder]

Is this what you need?

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If accurate then that decal is saying the device draws 5 amp hours per hour. So if you are running the machine for 8 hours you would be pulling 40ah. That is pretty high. Therefore you would want a big battery to keep the battery happy and long lasting. Something in the 90-100ah range. You will see this repeated over and over again by me in other threads. AGM batteries as in anything other than lithium-ion do not like to be drained down below 50%. It kills the lifespan of the batteries.

Here's a lengthy discussion on EP: http://forum.expeditionportal.com/threads/172079-CPAP-Power-Questions

Wiring up something like this between your CPAP machine or fridge will give you much more accurate power consumption readings.
T-Trees FT08 RC 150A Watt Meter Power Analyzer With Backlight LCD Hight Precision
by T-Trees
Link: http://a.co/bOIokeo

A fridge, for example, may have a 2.5AH draw. That of course is only when it is running. So depending on ambient temp and fridge temperature setting the amp draw will vary greatly. For the CPAP I would assume the power consumption would be a lot more predictable.

 

[Quicksilver]

Thanks, a lot of info there. I'll look into some of the suggestions made.

 

[slomatt]

Is this what you need?

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I think that is the maximum draw. What Respironics model do you have? We can look up the specs on their website.

 

[Quicksilver]

REMstar Pro C-flex +

Found a .pdf of the user manual (which I don't have a physical copy of). From the specifications page:

Electrical
AC Power Consumption (with 60W power supply): 100 – 240 VAC, 50/60 Hz, 2.1 A
AC Power Consumption (with 80W power supply): 100 – 240 VAC, 50/60 Hz, 2.0 A
DC Power Consumption: 12 VDC, 6.67 A
Fuses: There are no user-replaceable fuses.

 

[slomatt]

Great, thanks for the details. If you look towards the bottom of the following link there is a list of battery options and a calculator to determine how many hours you'll get out of them.
https://www.cpap.com/productpage/respironics-pr-system-one-remstar-pro-cpap-cflex-plus.html#power-tab

The 6.67A @ 12vdc rating from the manual seems really high, other CPAPs usually draw about 1A (with no humidifier or heated hose).

 

[slomatt]

Batteries are rated in Ah (ampere hour) which basically is a measurement how much power they can put out in an hour. For example, a 14Ah battery can put out 14A for 1 hour, or 1A for 14 hours. To find out how big of a battery you need you start with the current draw of your device and how many hours you need to run it, you then need to add extra capacity so that you don't completely draw down the battery and to compensate for power loss in cold weather.

(the following does not apply to Lithium based batteries)

In general you don't want to draw a deep discharge battery below 20%, and you can assume about 85% of rated Ah at 32 degrees F.

Let's say your CPAP draws 1A and you want to run it for 8 hours for 2 nights, so 16 hours total. Your draw is then 1A * 16hr = 16Ah. If you then assume a max 80% discharge and 85% of power at 32F (divide by .80, divide by .85) you wind up with a required battery size of ~24Ah.

The big question is the true draw of your CPAP if you disable the humidifier and the heated hose. 6.7A seems really high, and would result in you needing a really large battery, you might want to email the manufacturer and see if they have any more specific data. Or, you could get a battery and do some testing to see how long it lasts.

 

[James Feldermann]

I use a Respironics Dream Machine. I bought their 12v adapter and use a snowblower AGM battery, a 12v socket and a battery box. Total was just over $100. I've never used the humidifier and when I tested it at home on the battery and running it an average of 7 hours each night with the heated hose I quit after five nights and still had over 12v on the battery.

https://www.amazon.com/gp/aw/d/B00K8E0WAG/ref=yo_ii_img?ie=UTF8&psc=1

https://www.amazon.com/gp/aw/d/B00G8WLW2Y/ref=yo_ii_img?ie=UTF8&psc=1

https://www.amazon.com/gp/aw/d/B0000B12YQ/ref=yo_ii_img?ie=UTF8&psc=1

 

[NV Badlands]

More than the humidifier, the level of pressure you need is an important factor in your power level. I have a goal zero yeti 400, with the res-med air sense 10 auto. I've got the 12 V adapter for the machine hooked on the yeti, and I'm averaging about 16 wants an hour. Now that includes running a humidifier at a low level (2 of 8) which is all I need in the summertime- that usually creeps up about another five watts an hour during the winter when I have to turn the humidity up. Mine can do up to 120 W an hour if I ever need it, but thankfully my pressure is only about 50% of the machines capability.
When I first got my CPAP, my pressure was about 14 versus the 8 that I average now. I used about 50 W an hour.

 

[Quicksilver]

The 6.67A @ 12vdc rating from the manual seems really high

Maybe that's the high end if pressure, humidifier, etc are all maxed out?

 

[Quicksilver]

@jkxranger thanks for starting the thread, and thanks to everyone else for the input. This is one of the things I was going to need to tackle before my trip in September. Much appreciated.

 

[NV Badlands]

Maybe that's the high end if pressure, humidifier, etc are all maxed out?

Usually, yes. The wall wart always lists maximum capable draw, which is usually higher than actual.

And one additional bit of advice, a bad night can cause your compressor to work harder (if it's an auto), and thereby draw more power. Measure your power over the course of a week or two, then average it out.

 

[Quicksilver]

Good advice, thanks.

 

[slomatt]

Maybe that's the high end if pressure, humidifier, etc are all maxed out?

That's my assumption. I can't seem to find good power usage information for his device. Often manufacturers provide current draw at various pressures.

 

[aukaiiki]

Have you looked at the mini-cpap by Transcend? It is portable very small and battery powered. It is even TSA & FAA approved for use during a flight. This way you would only need to recharge the battery or batteries as you go. Just a thought.


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