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NDBirdman
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Saw one mentioned  on another thread so starting this one, don't want to hi-jack another.

My wife and I both use CPAPs.  Our RV is wired in the bedroom for 120 which is fine for when hooked to shore power.  We have several parks around us with no power, so dry camping will be done alot.  Probably do some boon docking and when my better half retires in a couple years, more than likely becoming snow birds.  I will run an outlet to the bedroom specifically for the 2 CPAPs.  My question I guess is how many 12 volt deep cycle batteries will I need on this circuit?    I will also need an inverter, don't have one yet.  This will be a set-up dedicated for this purpose so no other power leeches, I hope.  I might change the set-up it has now later to run the rest of the RV with more power.  It has one 12v deep cycle and small inverter currently to run a couple lights/fridge, etc..  I don't want solar on this RV, maybe on the new one we get when this money pit, er, bank payments are done on the truck.

 

Guess I can add, I will be picking up a 2k gen set so I can run battery chargers as needed although I would prefer to not have to run it.  A bat. set-up to run for 3 to 4 days would be good if it does not take a large bank of batteries. 

Edited by NDBirdman
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Just as an FYI, my old CPAP said the draw was 1VA (120V). I still don't know what a VA is equivalent to in either watts or amps. Anyhow, with a 300W inverter I could have all the sleep I needed and the CPAP was still running. I did wire an outlet from a 300w inverter in this trailer and have had no issues what so ever. The worst part is I can't even tell you what size batteries the dealer installed (I haven't though to look).

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11 minutes ago, Mntom said:

). I still don't know what a VA is equivalent to in either watts or amps.

Tom, FYI   VA= Watts/Power Factor. If the load is pure resistive with a unity one power factor then watts = same as VA. However if its an inductive load (like a motor) and if the PF is say 80% then VA = Watts/.8   Are you sure a CPAP draw is 1 VA ???? That's small. Id be more apt to believe like 1 amp at 120 volts which equals 120 watts  ??????????????????? BUT I DONT KNOW THE ACTUAL LOAD SO THIS MAY BE WRONG AS RAIN NO WARRANTY

 

7 hours ago, NDBirdman said:

My question I guess is how many 12 volt deep cycle batteries will I need on this circuit

  ND, of course the ONLY way to provide a half way decent answer is to know the actual current draw of the CPAP machines. That being said however again HOW MANY 12 volt deep cycle batteries you need depends on their amp hour storage capacity.

  Without knowing your battery type or capacity or the CPAP requirements I will still offer a few very broad and general tips if you plan to do very much dry camping.

  1) For a lot of extended dry camping (running two CPAP's plus other typical loads) I suggest the use of true deep cycle batteries versus any so called RV/Marine 12 volt "semi" deep cycle units like sold at Walmart. The very MINIMUM I'd consider would be say two Trojan T-105 6 volt True Deep Cycle Golf Cart batteries (or equivalents like Sams or Interstate or Costco etc etc) or even AGM in series giving you around 225 amp hours of energy storage while four such units wired in series parallel for 450 Amp Hours would be better. NOTE sure the twelves will "work" SUBJECT TO TYPE AND DESIGN AND SIZE and Id want at least two of them in parallel (Again all subject to size and type and actual loads) .      

2) For two CPAP's and other typical dry camping loads if you go ahead and get say a 1000 watt PSW Inverter you should have plenty of capacity and room for expansion EVEN THOUGH sure a 400 to 600 or so watt "may" suffice SUBJECT TO CPAPS AND OTHER ACTUAL LOADS  

3) If you can get 12 VDC powered CPAP's that would be more efficient then using an inverter

 

SUMMARY AND ROUGH APPROXIMATIONS not knowing actual loads SO DONT GET EXCITED ANYONE !!!!!!!!!

Id take a pure guess and still recommend at the very MINIMUM you start with at least 200 amp hours of battery energy storage (be they 6 or 12 volt) and Id prefer 400 amp hours,,,,,,,,,,,,,,,,,,,,At the very MINIMUM Id start with a 500 to 600 watt and Id prefer a PSW versus a MSW Inverter and even consider a huge 1000 watt to allow for future expansion..........Subject to actual loads I don't envision a single 12 volt RV/Marine semi deep cycle battery as getting you by nor a 300 watt Inverter for two CPAP's  BUT I DONT KNOW YOUR ACTUAL REQUIREMENTS so no freaking warranty

 

ONCE YOU KNOW THE ACTUAL LOADS AND RUN AN ENERGY AUDIT I could provide better advice, this is ONLY a rough pure guess remember. I run a 120 VAC CPAP plus furnace when cold and a small 120 VAC fridge 24/7 and lights and fans and water pumps etc and I do fine with 450 battery amp hours (Four Trojans) but I have a 3000 Watt PSW Inverter which is wayyyyyyyyyy more then you likely need.

 

 Best wishes and God Bless

John T 

 

   

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My CPAP draws up 200 watts AC or 60 watts 12 vDC (5.0 amps) but  continuous draw is dependence on how much the little humidity cabinet draws..

I have a 12V outlet by the bedside but only use when not plugged to shore power.  Previously I had a small Class C and slept many nights on the battery. I don't remember the battery size but the House battery was 3 years old and would run 3 nights without any charge source. I also ran the TV abit. I suspect I could have more run a 4th night but then continued on down the road .

You Shouldn't have any problem running 2 CPAP's on 12 VDC but what other loads will you require.

Clay

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So I just looked and my respironics BIPAP machine draws 5 amps at 12v.  Of course, the real current draw would probably depend on the actual pressure required and the humidity setting.  But at least that provides a baseline setting and it corresponds with what MS60ocb sees on his CPAP.  I'm surprised it doesn't require more energy.

That said, would it be worthwhile to install wiring to run everything at 12v?  How much power would be wasted going to 120v and back?

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Thanks for the replies.  I look closer tomorrow, wife has gone to bed and I don't want to turn on the lights to disturb her.  From what I gathered from mine, the little power supply (120 to 12) said it puts out 12v and 4.5 amps.  I also checked on line, I guess I can get a different power cable that connects directly to 12v.  I did not know I could do that, more research on that in the days ahead I guess.  That would be great if I can do that with our machines.  They are 2 different brands but I'm assuming her's is the same.  That would be great if I can just use a set of 6v golf cart batteries to supply all the power, no additional inverters.

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I use a portable freedom battery... I don't want to cause the heater to not light. I can get 2 nights from portable at my settings (respironics 60, fixed rate, no humidifier, no heated hose.).

Other advantage of the portable battery is I can use it in the house during a power outage, without plugging in to the generator power. It can also be setup as an auto backup for a.c. failure.

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8 hours ago, NDBirdman said:

That would be great if I can just use a set of 6v golf cart batteries to supply all the power, no additional inverters.

INDEED if you can use 12 volt CPAP's to avoid inverter use inefficiency and a couple 6 volt true deep cycle golf cart type batteries in series (versus a single 12 volt semi deep cycle RV/Marine battery) as always subject to actual loads you may well get by just fine..........Sure a high enough rated ??? single 12 volt battery may also get you by, but if you plan to do much dry boondocking I still suggest the use of true deep cycle battery or batteries.........My CPAP like others has variable temperature and humidity settings and pressure so actual use can still vary even with the same machine.

 John T   (Love my CPAP as it improves my rest and sleep and health sooooooooooo much)           

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6 hours ago, accumack said:

Not all cpaps are 12 volts some are 24volts. My resmed air sense 10 is 24 volts 3.5 amps. Check your brick it will give you the output.

What is throwing me off on this topic is what you actually mean by "it's 24 volts". When you use it at home on a 120v home electric system I have to assume you plug in a standard 2 prong plug into a standard wall jack and what you are plugging in is a transformer pack that connects to your CPAP? I have 2 of them (daily use and backup) and neither of them has any kind of transformer between the wall and the CPAP, so they are straight 120v units with which I will need an inverter to use off a 12v battery power feed.

Is that what you mean? Or does somebody make a "For RV use" CPAP that runs only on 12v or 24v but not 120v?

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I'm not aware of a CPAP that uses 120 volts directly they all have a transformer/brick that changes the voltage to something lower the Resmed Airsense 10  uses 24 volts you have to check the the transformer/ brick to see what your unit needs  if you want to bypass the transformer/brick.

 

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3 hours ago, accumack said:

I'm not aware of a CPAP that uses 120 volts directly they all have a transformer/brick that changes the voltage to something lower the Resmed Airsense 10  uses 24 volts you have to check the the transformer/ brick to see what your unit needs  if you want to bypass the transformer/brick.

 

Mine may have a transformer in the case, but there is no brick on either the O'Sullivan or the Resmed. From wall to CPAP. Not even a detachable cord. You may have just never had a model that was wired that way. I have been using one now for 21 years, and I am on my 3rd. Well, USING my 2nd, and I have a spare.

So not "all" of them have a brick. I have had 3 that do not.

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Just a couple of comments that might help.  First in order to conserve electricity, you need to use a 12v power supply line.  This is available for most CPAP models and if not available for yours, consider an upgrade.  An inverter wastes lots of power.

 

Second, the amount of power you will need varies considerably.  The big issue is the humidifiers and heaters.  My wife found she just cannot use her unit without heating and humidifying the air.  That can take several times the power needed to run the blower.  The biggest power hog is a heated air tube.  Most units will use about 1 amp @12volts to run the blower and a simple humidifier will take the power to about 3 amps.  So two units with consume about 50 AH/day.  So you will need about 100AH of battery for each night without charging.  Be forewarned that if you are going to replenish the batteries with a generator, a lot of time is required and it is best to have a quality 3 phase charging system.  With this sort of power drain, a solar system should be considered.  In fact for any sort of boondocking it is all but a necessity.  Also remember many campgrounds such as National Park campgrounds have limitations on generator use and often do not have any hook ups available.

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Just looked at my wifes and mine's brick.  Mine would be easy to run off a 12 volt system, it requires 12v at 4.5ah.  My wifes... hers requires 24 volts at 3.75ah.

So, I could easily run mine off a good deep cycle 12v system whether a single 12v, or dual 6v batt's.  My wife's, I could run off a system connected in-series.  Doing so, now I have in my opinion, too many batteries sitting in the bay just to run CPAPs.

I have seen online a batt. system to run one for a night, but it's for 12v CPAPs.  I did not look for one to run a 24v CPAP, time for more research.  Problem is, I would need to connect to shore power or generater, or inverter to charge the portable batt. pack for mine daily.  The one I'm using is my spare, I drag it around for hotels/hunting/fishing trips.  My wife has only one.  I just looked at my CPAP's brick.  LOL, my main CPAP is the same, 24v 3.75ah.  Yeesh.....

What kind of battery system would need if we both take along our main CPAPs?  4 12v batts set up in a parallel series or have I lost it?  From my thinking, am I just going to have to set up a batt system on an inverter for CPAP machine use only with solar chargers.... This much thinking is giving me a head-ache.

Maybe I will just have to limit our camping to sites with shore power, that would sure end alot of our plans on where we want to go.  I sure don't want to have to run a generator all night for power, that in itself would be a pain, the extra gas and noise... grrrrrrr  I need a beer, it's 5 o"clock some where, right?

 

 

Edited by NDBirdman
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My experience with two different CPAP machines is they use 20 to 35AH overnight using a heated humidifier.  This is less than one typical deep cycle batteries safe usage, which is 40AH (smaller 12volt) to 55AH (6v golf cart) .  The high number is my wife's old Respironics System One REMstar Plus that came with a heated hose, the low is the Resmed Airsense 10 Autoset, which both my wife and I now use. If I tried to turn off my wife's heated humidifier I would be told, "no way", since she feels like she has a cold without it.  

Edit: We have a large pure sinewave inverter since we have a residential fridge.  

Edited by Bill Joyce
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2 hours ago, Bill Joyce said:

my wife's old Respironics System One REMstar Plus that came with a heated hose, the low is the Resmed Airsense 10 Autoset, which both my wife and I now use. If I tried to turn off my wife's heated humidifier I would be told, "no way", since she feels like she has a cold without it.  

 

Bill has your wife tried tube sock. I have had good luck and we let the night temperature go to 55-60 degrees and summer turn the A/C to 67-68 degree.

My 6 year old Respononics I can preheat the water chamber (hold the on button down until the heater comes on) and then I ready to go to sleep.

Clay

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26 minutes ago, ms60ocb said:

Bill has your wife tried tube sock. I have had good luck and we let the night temperature go to 55-60 degrees and summer turn the A/C to 67-68 degree.

My 6 year old Respononics I can preheat the water chamber (hold the on button down until the heater comes on) and then I ready to go to sleep.

Clay

We have been fulltiming since 2003, my wife has had a CPAP since 2005 and uses a knitted tube over the hose.  It does not help the problem and she knows it.  20AH a night per CPAP is not much usage and we run two CPAPs these days and don't mind.  Why the obsession with helping me?  I guess it is not me you and others want to help.  You remind me of HandyBob, who insisted I change what I have for breakfast since running a toaster took too much battery.   That was over 10 years ago, I still use a toaster in the morning, my wife uses the microwave for some of her breakfasts, we are still fulltiming, we run the 3000 watt inverter/charger overnight and we are still able to dry camp.  

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  • 1 month later...

bigbiilsd: You are obviously not married to my wife.  The batteries they sell do not run the heated humidifier. When my wife's humidifier heater broke she could tell the difference immediately and ordered a replacement overnight.

Before we put in the residential fridge, two more batteries and a bigger inverter/charger,  I wired in a 300 watt pure sinewave inverter for my wife's CPAP for less than $150.   It worked great for the CPAP and we already had 4 golf cart batteries, so we had plenty of battery.   Now we run the residential fridge and two CPAPs with 6 AGM gc batteries and love our 3000 watt Magnum hybrid pure sinewave inverter/charger.  

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