CPAP on board

I use a CPAP machine when I sleep. I going on a houseboat cruise to Whitewater Bay next week for two nights. There is no generator on the boat.

The machine draws 1.5 amps of 110 volts to run. I have a 300 watt pure sine wave inverter.

Any suggestions on how to power this thing?

Mine has a 12 volt adapter because it runs on 12 volts with a transformer. Are you sure it runs on 120? You can probably turn off the humidifier for lower draw too.

Not a complete answer but maybe there is some wheat in my chaff.

HopCar said:

I use a CPAP machine when I sleep. I going on a houseboat cruise to Whitewater Bay next week for two nights. There is no generator on the boat.

The machine draws 1.5 amps of 110 volts to run. I have a 300 watt pure sine wave inverter.

Any suggestions on how to power this thing?

Click to expand...

If the houseboat has a 12VDC cigarette lighter plug, you could purchase the accessory 12V travel adaptor from the CPAP machine manufacturer and power it that way. Most machines I've seen have that option. No inverter efficiency losses that way either.

Come to think about it, you could also power your 300 watt inverter the same way if the lighter socket has enough capacity.

Well given the specs you quoted, the inverter should power your CPAP ok. But I don't know if the boat's DC system can handle it. The CPAP draws 1.5 amps A/C which means about 17-18 amps DC to the inverter (small pure sine wave inverters aren't very efficient. That will mean about 135 Ahs of use in an 8 hour period.

With no other DC loads (unlikely) you will need about 250 Ahs of battery capacity, plus you will need a way to recharge those 135 Ahs. If you move the next day then maybe the propulsion engine will have enough power to recharge them. Otherwise the battery must be much bigger.

So you need to check on the battery capacity of the houseboat and how it can be recharged the next day. Also how to plug into DC. A cigarette lighter outlet might work, but 17 amps is usually beyond its typical 15 A breaker supply.

David

HopCar said:

I use a CPAP machine when I sleep. I going on a houseboat cruise to Whitewater Bay next week for two nights. There is no generator on the boat.

The machine draws 1.5 amps of 110 volts to run. I have a 300 watt pure sine wave inverter.

Any suggestions on how to power this thing?

Click to expand...

Well, assuming you can obtain enough length of wire with a few spring clips on one end (adapting a cheap set of jumper cables has been done) and you can get to the batteries here's the math:

110VAC*1.5AhAC=165W/12VDC=13.75AhDC.... Round it up to 14 and add some for the parasitic load of the inverter, let's call it an even 20A.

So if said house boat has a house bank of 400Ah you can safely take a 10 hour nap.

If you figure our the wattage requirements for your 1.5 amp draw, that 300 watt inverter will work, but....you'd have to wire that thing into the boat system somehow.

Check for a 12v power supply for your cpap. Many of them have them available as an extra purchase item....If available, see if your houseboat will have a suitable 12v receptacle in your berth.

CPAP, like a lot of electronics, are DC inside, so that AC plug is another power supply that adds some to your power loss getting the thing to run...

That will at least get you using the boat native 12v system without inverter losses. The next thing is making sure the houseboat has enough amp hours for your stay...based on the 1.5 amp at 120v requirement, your CPAP will probably be drawing around 170-180 watts max (you will likely find it closer to 170 or less once you are powering from straight DC) which will end up being something like 14-15 amps...

The boat will need that X how many hours you sleep in amp hour capacity to run your CPAP. If you are sleeping 8 hrs a night you'll be using up 120 aH or so....On NWD my CPAP is a larger daily aH draw than our full sized Vitrifrigo refrigerator.

If the boat doesn't have that power, you might think of something so radical as taking a deep cycle battery with you and your inverter...I still suggest the 12V power supply for your boat, it really does help cut down some of the power requirements.

You can buy battery operated travel size Cpap machines. Cpap is something you use everyday for 6+ hours. If there is any aspect of your life you should invest top dollar in, its your Cpap collection.

Houseboat may have 120V inverter already installed. Check on battery capacity and recharge capacity. (Need to determine how long engine will be run and at what speed. Alternator's don't put out max amperage until they are at max rpm.)

You could buy a portable Li-ion battery that will give you overnight capacity, but of course that will need 120V to be recharged during the day.

(Edit: Honda 2000 would be a viable solution)

Thanks guys! Great feed back. My math seems about the same as yours. I need to know more about the house boat. I’m not even sure how it’s powered, probably outboard. I do have a Honda 2000 generator. Might have to bring that along.

The machine actually runs on 24 volts. The power supply says input 110 volts 1-1.5 amps, output 24 volts 3.75 amps. It also says 90 watts next to the output cable.

I bought a Goal Zero Sherpa 100AC, before I went to Puerto Rico a couple of years ago, right after Hurricane Maria.

I have an older ResMed CPAP unit and I don't use the humidifier. I can get 2 full nights with the battery, although I have to admit that the pressure for my CPAP is pretty low.

Here is the newest version of the Goal Zero Sherpa:



I like my older Sherpa. Its the largest portable battery that I can carry-on an airplane.

I paid $300 for mine a couple of years ago. I see that Goal zero has the new version on sale for $240 from $300.

Jim

Sorry, the new version of the Goal Zero may not work for the CPAP.

The old version had a 12V outlet at the back that I could use with the Goal zero supplied cable that I could then plug into the cigarette lighter adapter (brick) that I purchased separately from ResMed.

The new version of the Sherpa has a USB-C for DC output, something you may not have with the CPAP machine (I still use my ResMed from 2012).

You don't want to use the AC output from a battery as would be inefficient with the conversion from DC to AC to DC. Although this might still be enough to last one night.

Jim

I have the same numbers on the brick of my ResMed CPAP.

I confess that I don't know much, but I think this is the maximum power draw on my CPAP when using the humidifier (which consumes a lot of power).

I was concerned when I purchased my battery that it wouldn't last, but I had read on one of the CPAP forums, at the time, that a CPAP machine with low pressure would last significantly longer than one running at a higher pressure AND using the humidifier.

Jim

Going without the humidifier is a good point. I don't, so my power use is high; I've never tried computing what it would be without...I agree that would be a significant drop, assuming you can do that.

Good input here from a lot of folks. I have used CPAP for over 10 years, but only recently discovered CPAP forums and only recently came up with having a dedicated multiple machines for different uses. Right now my meger collection is the newest fanciest big brother machine that phones in my data at home, and the old tried and true machine out on the boat always ready to go, so I never have to take that contraption out there.

My gawd. I'd rather have open-heart surgery (done that) than be a slave of CPAP.

markpierce said:

My gawd. I'd rather have open-heart surgery (done that) than be a slave of CPAP.

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Where'd that come from?

I haven't had either problem but people do what they have to do. I've known several people that needed a CPAP aboard and they do just fine, just with some adjustment in the lifestyle.

markpierce said:

My gawd. I'd rather have open-heart surgery (done that) than be a slave of CPAP.

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Ignorant response. No one chooses medical conditions and I doubt HopCar would trade Sleep Apnea for a pace maker.

Here is a battery solution for all Cpap’s
https://www.cpap.com/productpage/portable-ac-outlet-cpap-battery

C lectric said:

Where'd that come from?

I haven't had either problem but people do what they have to do. I've known several people that needed a CPAP aboard and they do just fine, just with some adjustment in the lifestyle.

Click to expand...

Yes, probably a life-time bother while heart surgery doesn't necessarily require a pacemaker.

Gee, my attempt to be sympathetic backfired.

Mark, yeah I know what you mean. I've had several comments backfire and not just here. The intention is one thing, the effect is another.

My suggestion would be that you consider buying a battery anyway, especially if you are dependent on the CPAP. My sleep apnea is mild, so I use my machine for better sleep and to prevent snoring (wife sleeps much better as well)!

If you sleep apnea is more severe then you probably should have a back-up battery for emergency use. Batteries don't have to be Li, but that is my personal choice. Goal Zero (and others) also sell 200W and 400W batteries. This is a more economically choice that buying a battery from the CPAP manufactures and you can also use a battery like the Goal Zero for other uses as well, I sometimes use my 100W battery for my computer.

The down side is that if you can fly with these larger batteries, but if you are driving to where the boat is, it doesn't matter.

Jim

It's weird. Sometimes It feels like a relief to have it, and sometimes it feels like a ball and chain. It can be a real pain, but I definitely need it. I run mine off the inverter when I'm away from shore power most of the time. I also have a couple of these batteries:

http://www.batterypowersolutions.net/product/freedom-cpap-battery

They're stupidly expensive, and I only get one night's sleep out of one, and that's without the humidifier, but they've saved my bacon before.

I got them for camping, and have used them several times with my recent house bank and charging issues.

I think I’ll run a little test tomorrow night. I’ve got a group 24 starter battery that is rated 135 amp hours. I’ll see what happens when I run the CPAP with this battery and my inverter.

This is a good reminder for me to come up with some more solutions, thanks for the battery link, I hadn't researched enough to know about CPAP-specific batteries.

I have fairly bad apnea. When my old CPAP suddenly and completely failed this past April, I did not have a spare. Because it had been so long since I had been in to a sleep Dr. it was a 3 day process to get a new one. I literally ended up buying a used one off craigslist and learning how to reprogramming it off the internet so I could get it set to my pressure. I found that for the two nights until I found it I was not able to sleep. By day two I was so far gone I considered it unsafe to try to go to work.

Now that I have NWD with her redundant power and spare CPAP, I consider her my refuge in case of overnight power outage at the dirt house. There are some things off limits to me in life that maybe one of these CPAP batteries would solve.

I've been using a Resperonics CPAP for something like 12-14 years, cruising in a couple of different boats all the while. The Resperonic unit is normally powered by 120V AC for the fan motor and the humidifier for home use as well as hotel travel. Resperonics also has a 12V adaptor (plugs into a cigarette lighter socket) for boat and RV use. The first boat in which I used the CPAP was a 28' Shearwater Yawl (Edey & Duff trailerable cruiser) in which I installed a second 12V group-27 battery as a "house battery" just to power the CPAP. The original 12V Group-27 battery was used to start our 9.9hp Yamaha outboard auxiliary power as well as nav lights and VHF radio. The boat's electrical system was very basic; no other electric or electronic accessories.

The second boat in which I use the CPAP is the Albin-25 pictured at the left. It came to us with a pair of 12V Group-27 batteries for both House and Starter circuits.

I could run the CPAP for a week on the House battery in the Shearwater without recharging. Yes, it would be recharged at a very low rate when under power with the outboard.

I can run the CPAP an unlimited number of days in the Albin because the Volvo-Penta Diesel has a much stouter alternator for recharging while underway.

Note: the 12V adaptor will NOT power the CPAP humidifier, however, I figure our boat is always in a humid environment on the water when cruising. We also use the Albin as an RV in KOA Campgrounds when traveling cross-country to distant water and I can use the humidifier with 120V campsite power. If camped for a night at a truck stop without 120V power, I've never suffered any ill effect by going without GPAP humidity for a night on the highway, not near a water environment.

We've also chartered a couple of boats; a Juneau-41 with The Moorings in the BVI, and a LeBoat 40 footer on a canal in France. Both boats had 12V sockets near the berths for the CPAP.

I think the problem is solved. I went down to Flamingo today and spoke to the house boat people. They said I could rent a generator to take with us. I think it will run the air conditioner as well. Looks like we’ve got some warm weather headed this way so the AC will be nice.

My friend Snapper suggested we go for a boat ride into Whitewater Bay today. That gave me a chance to talk to the houseboat folks and get an idea of what they are like.

Your Honda will probably be a lot quieter

SoWhat said:

Your Honda will probably be a lot quieter

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Yes but it probably won’t run the air conditioner. If the weather will be cool, I might take it.

MAXOAK Battery for CPAP

Depending on your make/model, here is a solution from Amazon that has adapters for most popular CPAP machines. I have one and my CPAP (ResMed AutoSense 10) only draws 11% of the battery's capacity per night. Significantly cheaper than the manufacturer options and way more capacity.

https://amzn.to/33SRQ2B

HopCar said:

I use a CPAP machine when I sleep. I going on a houseboat cruise to Whitewater Bay next week for two nights. There is no generator on the boat.

The machine draws 1.5 amps of 110 volts to run. I have a 300 watt pure sine wave inverter.

Any suggestions on how to power this thing?

Click to expand...

Lots of others have already provided most of what I'm going to say, but I thought I'd at least add a bit more detail from my testing and use.

I have a ResMed AirSense 10 CPAP with humidifier. When I got it a year ago, it was a life-changer. Not only did my partner not want to murder me anymore, but I now have 2x-3x the energy and stamina than I did before, which lets me do many more boat projects!

I live aboard about 50% of the year, so I use it both at home and on the boat. I did a lot of testing, being a DC power nerd, on both using it aboard, at home, and in power failure situations in both places. The last thing I want is to wake up pseudo-suffocating because I have no power...

I also have been (strangely) camping a bit more lately, and have taken it with me there as well.

I investigated portable CPAP machines and found them to mostly be a waste of money. Many of them have severely limited functions, and end up requiring more equipment to use in addition to your normal machine. For people who travel a lot on planes or trains and need to sleep there, they make sense. For a boat, not so much.

The CPAP branded batteries are also not a great investment. They seem to be purpose built for specific models in many cases, and limited overall amp hours. Again, for someone traveling a lot, these would make sense paired with a portable CPAP.

The biggest draw in the ResMed (and most others) is the heated tube and humidifier. Both are heated, and can account for more than 80% of the power draw. All of the more modern units have controls to turn this off, and will dramatically reduce the power usage.

With humidifier/tube heat on - around 300 watt hours in one night
Without - around 80 watt hours in one night

While camping, I use a Yeti 400 Lithium power station to keep it running. I can go 3 nights on one charge of the Yeti, plus charging phones and other small things.

At home I also use the Yeti in case the power fails, but I leave the tube heater and humidifer on.

On the boat, I had been using the inverter via a normal AC plug, but switched to the 12v adapter a few months ago. I use the humidifier and tube heater on the boat because I have the power available.

The 12v adapter that seems more efficient than using the AC wall plug. I use this pretty much everywhere now because I'm using the 12v ports on the Yeti at home/camping, and a 12v socket on the boat. I would highly recommend getting that if you continue to use the CPAP off of a battery.

I’ve been a CPAP use her for about 10 years.

My present CPAP is hooked directly to a 12 V mains and uses about eight to ten amp hours per night.

I have no need for the humidifier on the water since the water keeps the boat quite humid.