BobBeery Posted February 5, 2013 Share Posted February 5, 2013 I start CPAP tomorrow. There will be times we overnight without shore power. I can use my Honda generator to run the CPAP but I may not want to have the gen. with me every time we are out. I can rig a way to run the CPAP off the house battery. The question is how long, or how many nights I might expect the house battery to last. ( I ran CPAP in search and did find 5 entries, but battery life was not mentioned) I know there can be no exact answer; I just want a ballpark idea. Note: this machine will have a heated hose which many do not, so current draw may be higher for me. Quote Link to comment Share on other sites More sharing options...
waiter Posted February 5, 2013 Share Posted February 5, 2013 find out how many amps it draws, multiply that by 10, thats how many amps it will draw at 12 volts thru an inverter. your battery will be able to supply about 70 amps You might also check about operating the machine with a "modified sine wave" inverter. (the inexpensive inverters) I've heard of people running CPAP machines on the cheap inverters, it should work, but your on your own for testing. John Mc 88 Dolphin 4 Auto Quote Link to comment Share on other sites More sharing options...
zero Posted February 5, 2013 Share Posted February 5, 2013 From what I've read, CPAP machines use 40 - 80 amp-hours in 8 hours. Depends on the machine and what setting it is on. So a typical type 27 deep-cycle battery (typical for an RV) run down to a 50% discharge would run a CPAP for one night with no problem. Quote Link to comment Share on other sites More sharing options...
Boots Posted February 5, 2013 Share Posted February 5, 2013 Hi Bob, I set up a friend who was going camping with a CPAP; here is what I did I lent him a 225 amp/hr battery (fully charged) I lent him a 100 watt invertor (Canadian Tire) I had him check his CPAP machine name plate for amperage; 4.3 amps Doing the math for you, it turned out that the draw 43.6 amps DC This worked out to 4.9 hrs theoretical, in fact he had no troubles for the entire night. The battery was recharged each day. Brian Quote Link to comment Share on other sites More sharing options...
Riverman77 Posted February 5, 2013 Share Posted February 5, 2013 Hi guys, Sorry to slow down the progress of this thread of discussion with a dumb question. Can anyone chime in with what exactly CPAP means or stands for? I've simply never heard of this term before. I'm assuming it has something to do with the stock, onboard power inverter. Thanks. -Riverman77 Quote Link to comment Share on other sites More sharing options...
waiter Posted February 5, 2013 Share Posted February 5, 2013 Continuous Positive Airway PressureMeant to improve sleeping. Basically, its small face mask and an air pump. The unit has inteligence in it to switch on the air pressure as you breath and keeps a small positive pressure in your airway at all times.One of the problems with Sleep Apnea, these people sometimes stop breathing (for various reasons) in the middle of the night. One of the main causes of this is throat muscles relax and collapse the airway passages and the person can't breath. They then surge and momentary wake up, catch their breath, then fall back asleep. Usually the person who suffers doesn't know they are doing this, all they know is that they don't sleep worth a crap. And of course, if your sharing a bed, the other person doesn't sleep at all. because your constantly waking, gasping for air. The CPAP machine keeps the airway from collapsing by keeping a small (2 or 3 inches) pressure in the airway at all times, kind of like keeping it inflated a little bit. How do I know all this? I suffer from Primary Insomnia, I went thru the sleep clinic and there is nothing wrong with my breathing, I'm an extremely light sleeper, and normally am perfectly aware of everything going on around me even when Im sleeping. I fight the urge to go cut the grass at 3 in the morning :-) JOhn Mc 88 Dolphin 4 Auto Quote Link to comment Share on other sites More sharing options...
zero Posted February 5, 2013 Share Posted February 5, 2013 Hi Bob, I set up a friend who was going camping with a CPAP; here is what I did I lent him a 225 amp/hr battery (fully charged) I lent him a 100 watt invertor (Canadian Tire) I had him check his CPAP machine name plate for amperage; 4.3 amps Doing the math for you, it turned out that the draw 43.6 amps DC This worked out to 4.9 hrs theoretical, in fact he had no troubles for the entire night. The battery was recharged each day. Brian I suspect that 4.3 amp rating was the max surge current that machine only drew at first start-up. Most CPAP machines draw less then 1 amp @ 120 VAC once running. That's 6 amps @ 12 volts DC. A 225 AH battery is safe when run to half-charge . . i.e. 112 amp-hours. That 112 amp-hours with 10% inverter loss is 101 amp-hours. 101 amp-hours should run the average CPAP for 16 hours - but that depends on what setting it's on. My mother had one years back and I know it had two settings - a high and a low. "High" drew twice the current as "low." Quote Link to comment Share on other sites More sharing options...
zero Posted February 5, 2013 Share Posted February 5, 2013 I suffer from Primary Insomnia, I went thru the sleep clinic and there is nothing wrong with my breathing, I'm an extremely light sleeper, and normally am perfectly aware of everything going on around me even when Im sleeping. I fight the urge to go cut the grass at 3 in the morning :-) JOhn Mc 88 Dolphin 4 Auto I suspect that is not all that uncommon. As an adult I've always been like that and so is my wife. A doctor once prescribed Amitriptyline when I had gotten pretty run down from lack of sleep. It really worked except after taking it for a week - I started to feel like an ax-murderer-zombie. It has some weird effects on my brain and I stopped taking it. Now when I get real run down from lack of sound sleep I take two Aleve. That will let me sleep much better for maybe two nights and then the process starts all over again. I am amazed when I see people sleep so soundly you have to drop a bomb on them to make them wake up (like our 9 year old kid). I envy it in a way but . . . I also like being aware of what's going on around me all night. Curse and a blessing I guess - but more towards the curse side. Quote Link to comment Share on other sites More sharing options...
Riverman77 Posted February 5, 2013 Share Posted February 5, 2013 Thanks guys, for the reply. I would have never guessed what it was that was being discussed, from the previous postings. A friend of mine's Dad uses exactly one of those machines, when he sleeps at night. I simply didn't know the name of such a snoring problem. -Riverman77 Quote Link to comment Share on other sites More sharing options...
WME Posted February 5, 2013 Share Posted February 5, 2013 My wife's CPAP uses a wall wart to provide power for the unit. The mfg offered a 12v cigarette lighter plug as an option, making your own would not be rocket science. The machine discharges my gp 31 battery in 3 days with out charging. The humidifier heater uses most of the power so run the humidity level lower than you would at home. Quote Link to comment Share on other sites More sharing options...
waiter Posted February 5, 2013 Share Posted February 5, 2013 WME Good point about the wall wart. You might check the wall wart output, if it puts out 12 - 15 volts, you could probably run the unit directly off the battery, without any need for inverters, etc. JOhn Mc 88 Dolphin 4 Auto Quote Link to comment Share on other sites More sharing options...
Maineah Posted February 5, 2013 Share Posted February 5, 2013 My sister also has one and it came with a lighter cord. Quote Link to comment Share on other sites More sharing options...
BobBeery Posted February 6, 2013 Author Share Posted February 6, 2013 I now have the CPAP machine to look at. First--it is 90 watt. Second--the power cord is much like that of a laptop computer. Household AC goes to a converter box (much larger than the one for a laptop) then a second cord goes to the machine. Near each end of the second cord there is a built -in cylinder much like the one on a laptop cord just before the laptop. This second cord is built into the converter so there is no way to plug something else into it. The connector on the end of the cord is one I have never seen before, it has three pins arranged in a triangle. One pin is only half the thickness of the other two. Now the electric details. Converter output is 24V, 3.75 amps DC. If I boost my 12V from the coach deep-cycle up to 24V somehow, it will draw at least 7.5 amps, more if there is loss in the voltage boost. So I figure about 65 amp-hours per night, maybe 70. Add in lights, etc. I would have no problem getting one night, A second night is questionable. My Dolphin is stored in a farmer's field ($54 for all winter, $54 for all summer) so I can't look tonight to get the AH spec on my battery. Also the Dolphin has the original converter only, NO inverter. I really don't want to add a second battery and hook up in series to get 24V. Is there an appliance available that will boost 12V to 24V at that amperage? Thanks you Waiter, jdemaris, Boots, Riverman77, WME and Maineah for your replies. Quote Link to comment Share on other sites More sharing options...
zero Posted February 6, 2013 Share Posted February 6, 2013 Is there an appliance available that will boost 12V to 24V at that amperage? Thanks you Waiter, jdemaris, Boots, Riverman77, WME and Maineah for your replies. Yes . . . it would be a DC to DC boost converter. But they are not cheap and if spending money - seems it would be better spent on an inverter and just run the CPAP off the AC the inverter makes. Then, you've got the inverter for other uses if the need comes up. Yes, it adds some loss but you'll still have plenty of battery to do the job. A 400 watt mod-wave inverter for $35 will probably do the job just fine (much depends on the brand of inverter). There are good and bad inverters on the market. I've had zero problems with AIMS when it comes to cheap inverters. Like this one. http://www.theinverterstore.com/400-watt-power-inverter.html Quote Link to comment Share on other sites More sharing options...
waiter Posted February 6, 2013 Share Posted February 6, 2013 Yah, converting 12 to 24 isn't cost effective. Like JD says, sounds like your a good candidate for an inexpensive inverter, Try a 400 watt, these are cheap. Run the CPAP by night and the laptop or small TV by day.Your toyhouse probably has a group 27 battery, good for 70 - 90 amps, so your probably good for at least one night. John Mc 88 Dolphin 4 Auto Quote Link to comment Share on other sites More sharing options...
BobBeery Posted February 12, 2013 Author Share Posted February 12, 2013 After diligently searching both the CPAP owner's manual and the mfg's website I learned that the CPAP maker has a DC/DC converter with all cables and battery clips. There are built-in protections against too high a voltage to protect the CPAP and against too low a voltage to protect the deep-cycle from excessive discharge. Cost from the local dealer is $50 out the door. The website also told me that a modified sine wave (square wave) inverter is okay. Pure sine wave is not needed. I won't be using the Toy until at least mid-May so I have time to decide which way to go, But if I had to choose right now I would probably get the DC/DC converter. There is too much other work to do on the Toy Quote Link to comment Share on other sites More sharing options...
Maineah Posted February 12, 2013 Share Posted February 12, 2013 It probably is a good idea to use the unit designed for it . The price for the peace of mind is well worth it. Quote Link to comment Share on other sites More sharing options...
waiter Posted February 12, 2013 Share Posted February 12, 2013 Bob, This is great news. Can you post a couple photos, links with model numbers, or other info.John Mc 88 Dolphin 4 Auto Quote Link to comment Share on other sites More sharing options...
zero Posted February 12, 2013 Share Posted February 12, 2013 . The website also told me that a modified sine wave (square wave) inverter is okay. Pure sine wave is not needed. The difference isn't one of necessity. The difference is efficiency. A so-called "pure" sine wave inverter can run an electric motor with less DC electricity used. Not a huge difference though. Mod-waves are less efficient running electric motors but sometimes beat sine-wave inverters with some types of resistive-load circuits. If you have an ample sized battery, it doesn't matter. If things are close - the sinewave runs a motor longer on X amount of battery power. I put "pure" in quotes since there's isn't a sine-wave inverter on the market for less then a couple of thousand dollars that makes a "pure" sine-wave. A genuine Hertz Cycle sine-wave has rounded peaks and nadirs. These consumer-grade portable sine-wave inverters have square -steps in a wave similar to a mod-wave. They just have more and they are smaller. My point is - none that I know of exactly replicate AC power from the grid unless you spend many thousands of dollars. Inverters that really make true sine waves cost around $1 per watt. The consumer-grade portable inverters sold as "true" or "pure" sine-wave are often 20 to 30 cents per watt. A mod-wave is often 6-7 cents per watt. Quote Link to comment Share on other sites More sharing options...
BobBeery Posted February 13, 2013 Author Share Posted February 13, 2013 Waiter, Sorry I do not know how to do thumbnails or even links. My machine is a Resmed S9 with attached H5i humidifier and heater. I also have the heated hose. The converter is called a S9 DC/DC Converter 24V 90W. It is part number 36970. For all the info from the website go to www.resmed.com, click 'Patients and Families', click 'service and support', then 'FAQ' then 'How can I operate my resmed device with a battery?' To see one, after 'Patients and Families' click 'products' then 'accessories' then 'device' and scroll down to 36970. Note well: the price of $50 out the door may well be only from the dealer I am using. There is no suggested retail shown on the website. Quote Link to comment Share on other sites More sharing options...
xanthogar Posted February 13, 2013 Share Posted February 13, 2013 They sell rechargable battery kits for most cpaps that last 2-5 days then need to be recharged that could be a good option. Quote Link to comment Share on other sites More sharing options...
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