CPAP system backup/camping power

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  • Mike90250
    Moderator
    • May 2009
    • 16020

    CPAP system backup/camping power

    I'm gleaning through several threads to compile this data.
    If your CPAP unit has a 12VDC power supply, great ! If you don't need the humidifier, even better, you will likely be able to lift the battery pack.

    The medical supply shops will gladly sell you a sexy Lithium battery, that will only last you two or three nights before needing recharge. (but no humidifier with them either)

    You can lug around a Group 24 Marine battery ($100) and wire a cigarette lighter to plug the CPAP automotive cord into. That will get you 3 or 4 days before you HAVE to recharge it.

    Or, I found a suitably sized Jump Start power pack (battery booster) that had a cigarette lighter on it's front panel. Uses a wall wart to recharge from AC power, and it came with a automobile charge cord to recharge from while driving. (Or I can charge it from a solar panel.)

    What you need to do, is to discover how much power the machine consumes overnight, and obtain a battery that can supply at least twice that much power for a night (only drains the battery 50%). Draining a battery more than 50% really shortens it life from hundreds of cycles, to less than a hundred.

    The math. You want to calculate power in Watt Hours. 45watts * 6 hours = 270 wh

    Look at the CPAP or it's power brick. Does it list wattage ? 3A at 12VDC ? 1A at 120VAC Volts * Amps = watts,
    so 3 * 12 = 36w * 6 hr = 216wh

    Same for batteries, a 20Ah rated battery * 12V = 240 total watt hours in it, 120 of which are useable for long lifetime. So this
    little exercise shows that your really need a 40ah battery for this CPAP machine. I got liucky, my 18ah battery will run my machine (sans humidifier) for 2 days @ 10" pressure, before I need a recharge.

    So give it a try, and see what works for you. And you can jumpstart the car with it too!
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister
  • PNjunction
    Solar Fanatic
    • Jul 2012
    • 2179

    #2
    I also use jumpstarter packs for a variety of small jobs - with solar too, but have a caution for those who must rely on it functioning for CPAP duties:

    Many of these jumpstarters include USB ports, inverters and the like. The problem with that is that depending on the manufacturer's quality of design, if you overload or fry the usb or inverter, it can take out the logic board of the pack itself, rendering it a total brick. Even high-priced boutique all-in-one camping type boxes can suffer from a poor design goal. How much of the box becomes non-functional is hard to predict, but all it takes is one frustrating smoke-test out in the field where replacements may not be quick in coming.

    I guess what I'm saying is that if you are truly dependent on the CPAP working via the dc outlet, then instead of using the box's other built-in features, perhaps rely on the dc cigarette lighter jack to supply power to 12v > 5v mobile usb adapters, external small inverters etc.

    Lately when I've chosen a box for this application, I do without all the other frills for this very reason. I just basically need a box with an outlet, and of course clamps to allow for an actual jumpstart.

    Most of the time, I also do away with the wall-wart, or ignore it if it is integrated, and use either the cigarette lighter socket, or clamps themselves (with safety in mind!) to apply a quality charger to the box, like a Tecmate-Optimate, Battery-Minder or similar.

    It's just my way of reducing the possible additional points of failure when a remote CPAP machine is vital.

    Comment

    • SunEagle
      Super Moderator
      • Oct 2012
      • 15126

      #3
      Originally posted by PNjunction
      I also use jumpstarter packs for a variety of small jobs - with solar too, but have a caution for those who must rely on it functioning for CPAP duties:

      Many of these jumpstarters include USB ports, inverters and the like. The problem with that is that depending on the manufacturer's quality of design, if you overload or fry the usb or inverter, it can take out the logic board of the pack itself, rendering it a total brick. Even high-priced boutique all-in-one camping type boxes can suffer from a poor design goal. How much of the box becomes non-functional is hard to predict, but all it takes is one frustrating smoke-test out in the field where replacements may not be quick in coming.

      I guess what I'm saying is that if you are truly dependent on the CPAP working via the dc outlet, then instead of using the box's other built-in features, perhaps rely on the dc cigarette lighter jack to supply power to 12v > 5v mobile usb adapters, external small inverters etc.

      Lately when I've chosen a box for this application, I do without all the other frills for this very reason. I just basically need a box with an outlet, and of course clamps to allow for an actual jumpstart.

      Most of the time, I also do away with the wall-wart, or ignore it if it is integrated, and use either the cigarette lighter socket, or clamps themselves (with safety in mind!) to apply a quality charger to the box, like a Tecmate-Optimate, Battery-Minder or similar.

      It's just my way of reducing the possible additional points of failure when a remote CPAP machine is vital.
      Good info to know.

      While I use a CPAP machine it is not critical for me to go a day or so without (although I do snore a little without one). But for those that really need it you do not want to lose your power source when you are out in the wild.

      So as a recommendation I would have a backup power source in case the first one (even if it was a plain jane one) fails.

      Comment

      • PNPmacnab
        Solar Fanatic
        • Nov 2016
        • 425

        #4
        I just finished living off grid for 3 months with an Airsense 10. As said before the humidifier takes a lot of power and was turned off. I was near water and with normal humidity in the summer didn't miss it at all. My pressures are fairly low (8) and each night I consumed around 10AH, peak usage was about 27W. I used just a car battery from a vehicle I don't bring with me. These auto batteries are typically in the 60AH range and you don't want to use more than 80% before a recharge. Typical deep discharge/marine batteries aren't much better. I recharge with solar panels and the minimum I would recommend is 300W of panels. I found that a 400W converter used less overhead power than a 200W inverter. If clever, cut the wires to the fan which uses a lot of power. A 400W unit will run quite cool on this 30W load without heating issues.

        Comment

        • thastinger
          Solar Fanatic
          • Oct 2012
          • 804

          #5
          I bought all the adapters for my for my dreamstation which runs directly off 12V. The humidifier is needed for me since I have a hybrid full face (I'm a mouth breather). When we lost power for the hurricanes I just took the battery out of one of our cars and used it overnight, then charged it up the next day with a battery charger running on the generator. Not necessary for me to have/store a one purpose battery I may never use before it is dead, or even worse buy it, not use it in 3-5 years, then it be no good when I reply on it. Don't want a new part-time job of care & feeding a special battery which I MAY need to use every couple of years or so.
          1150W, Midnite Classic 200, Cotek PSW, 8 T-605s

          Comment

          • JSchnee21
            Solar Fanatic
            • May 2017
            • 522

            #6
            Well, these are rather expensive ($500) but from the reviews many folks seem to like them for CPAP's. My dad has a CPAP, and camps a lot, but they never stay anywhere without electrical service (and water).

            Anker Powerhouse, Compact 400Wh / 120000mAh Portable Outlet, Generator Alternative Rechargeable Power Source with Silent DC/AC Inverter, 12V Car/AC/USB Outputs for Camping, CPAP or Emergency Backup

            (www).amazon.com/Anker-Powerhouse-120000mAh-Alternative-Rechargeable/dp/B0196GQAKM/ref=sr_1_3?ie=UTF8&qid=1543456194&sr=8-3&keywords=anker+camping+battery#customerReviews

            Comment

            • PNPmacnab
              Solar Fanatic
              • Nov 2016
              • 425

              #7
              I have a plug just inside the grill of my car that I use to power all of my 12V devices. Beats pulling a battery out. Adding a solar panel and small charger make a nice emergency system.For years I just plugged my camp into the car.

              Comment

              • Buck Rogers 2000
                Junior Member
                • Mar 2012
                • 26

                #8
                I've used a Goal 0 Yeti 400 (not lithium) for my CPAP. With the humidifier on, it drained 60% of the (AGM) battery in one night. If you have a solar panel large enough, with enough sunlight, theoretically you could boondock for quite a while. Of course, turning off the humidity would stretch it out quite a bit. Note: If you're interested in this unit, I don't recommend Goal 0 lithium units. Their batteries aren't user replaceable, they incorporate PWM controllers and their input power is throttled.

                Comment

                • PNPmacnab
                  Solar Fanatic
                  • Nov 2016
                  • 425

                  #9
                  Humidifiers and heated hoses are a super big drain, I turn them both off. That drops me down to 6-7 AH a night. I don't really miss the humidity for four months since it is not a dry area. Also built my own power pack to boost 12 to 24 which is on a timer so it doesn't run all day, a very rude alarm clock should I sleep late.
                  Last edited by PNPmacnab; 09-18-2019, 06:27 PM.

                  Comment

                  • BoloMKXXVIII
                    Member
                    • Jun 2018
                    • 51

                    #10
                    I use a Respironics CPAP (with 12v cord) and when camping I do not use the humidifier. I used to use a 80Ah AGM battery but it was difficult to move around without killing my back. I built a 20Ah 12v LiFePo4 battery pack and have managed to run 3 nights without having the low voltage limit cut off power (set for 11v). I admit I do not sleep long (camping or otherwise) and only use 8" pressure. I found attaching a single 100w 12v solar panel to the battery via a PWM controller keeps the battery topped off during the camping trip. Knowing I have at least 3 nights even without the solar panel gives me comfort.

                    Comment

                    • coarsegoldkid
                      Junior Member
                      • Jan 2020
                      • 3

                      #11
                      I would like to run my Resmed Airsense10 off a small solar system essentially a solar generator at my cabin. The Airsense10 comes with a power brick AC120 to DC24dvc converter. The Airsense10 is labeled 24 Volts input. However, Resmed sells a 12vdc to 24vdc converter for car camping. This suggests to me that the Airsense10 will operate on 24 vdc. That being the case I should be able to build either a 24vdc or 12dvc LIPo battery and charge with a controller off a panel. If a 12vdc then I get the Resmed DC to DC converter. If 24DVC I run it straight off the battery. What do you think?
                      What I like about building the battery from discrete cells is if later I decide to build a cabin size solar system I'll buy more cells and panels plus the rest of the kit to make more capacity and run the cabin on AC.
                      Last edited by coarsegoldkid; 01-21-2020, 12:01 PM. Reason: I rechecked the Resmed power brick and it is 24vdc not 19vdc. Too many bricks. My computer uses a 19vdc brick.

                      Comment

                      • BoloMKXXVIII
                        Member
                        • Jun 2018
                        • 51

                        #12
                        Originally posted by coarsegoldkid
                        I would like to run my Resmed Airsense10 off a small solar system essentially a solar generator at my cabin. The Airsense10 comes with a power brick AC120 to DC19dvc converter. The Airsense10 is labeled 19 Volts input. However, Resmed sells a 12vdc to 24vdc converter for car camping. This suggests to me that the Airsense10 will operate on 24 vdc. That being the case I should be able to build either a 24vdc or 12dvc LIPo battery and charge with a controller off a panel. If a 12vdc then I get the Resmed DC to DC converter. If 24DVC I run it straight off the battery. What do you think?
                        What I like about building the battery from discrete cells is if later I decide to build a cabin size solar system I'll buy more cells and panels plus the rest of the kit to make more capacity and run the cabin on AC.
                        If only it were an issue with voltage. I don't know what the CPAP manufacturers do, but I was unable to make anything work but their "official" cable. Matching voltage and amperage did not seem to be enough. I would go with their official car cable and build around it. A pre-built portable power station (solar generator) would probably be cheaper than building one yourself. Just make sure it has a regulated 12 volt output. Most do not.

                        Comment

                        • Mike90250
                          Moderator
                          • May 2009
                          • 16020

                          #13
                          Please stop using the phrase "solar generator". Such a thing does not exist. A generator is a revolving magnetic field. Just because Marketing Bozos use it, does not make it right.

                          A note of caution about using a solar powered charger, Many will produce 15V to the 12v battery, in order to charge the battery faster in the limited solar hours. Your CPAP will not likely be operating during that time, and so you should un-hook the 12-24V adapter until bedtime, when the system will be closer to 13v.
                          I'd advice you to use the factory converter cable, and let it be responsible for the proper operation of your machine.
                          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                          solar: http://tinyurl.com/LMR-Solar
                          gen: http://tinyurl.com/LMR-Lister

                          Comment

                          • BoloMKXXVIII
                            Member
                            • Jun 2018
                            • 51

                            #14
                            I did start with portable power station as that is the proper terminology. I included the marketing hype name as some people are more familiar with that term. Thank you for the statement about disconnecting the CPAP during charging. It most likely would not be a problem, but when dealing with an expensive machine people rely on, it is good practice.

                            Comment

                            • PNPmacnab
                              Solar Fanatic
                              • Nov 2016
                              • 425

                              #15
                              I run my A10 off a 12V battery at my camp and a 12 to 24V boost converter. Don't know where you got 19V. However, it likely has internals that would run that low. I used one of those $6-7 adjustable boost converters and set it to 24V exactly. That cable is special and a standard HP cable will not work. Maybe if you ground the plastic end off. If you notice, pulling the plug out slightly causes an error to be displayed on the screen that the plug is not fully inserted. The center pin requires a 2.7K resistor to a 3.3V source. Do not power the center pin directly. It designates a 85W supply. There is an easy thevinin equivalent using two resistors from the 24V. I could look it up if interested. I just cut the DC cable on the AC power pack. You can just wire up a three pin connector at the cut and have both worlds. I never did that because these packs are only $10. Still have it if an emergency should happen. I even have mine on a digital timer so it turns off in the morning should I leave early and forget to turn it off. That can be a really rude alarm clock if I sleep late.
                              Last edited by PNPmacnab; 01-13-2020, 04:24 PM.

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