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HopCar 12-07-2019 03:35 PM

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?

Xsbank 12-07-2019 04:08 PM

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.

LarryM 12-07-2019 04:15 PM

Quote:

Originally Posted by HopCar (Post 826658)
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?

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.

DavidM 12-07-2019 04:16 PM

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

oscar 12-07-2019 04:18 PM

Quote:

Originally Posted by HopCar (Post 826658)
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?

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.

fractalphreak 12-07-2019 04:21 PM

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.

tiltrider1 12-07-2019 05:38 PM

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.

SoWhat 12-07-2019 05:54 PM

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)

HopCar 12-07-2019 06:07 PM

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.

JLD 12-07-2019 06:18 PM

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:

https://www.trawlerforum.com/forums/m...icture5732.jpg

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

JLD 12-07-2019 06:44 PM

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

JLD 12-07-2019 06:51 PM

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

fractalphreak 12-07-2019 07:25 PM

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.

markpierce 12-07-2019 07:58 PM

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

C lectric 12-07-2019 08:16 PM

Quote:

Originally Posted by markpierce (Post 826727)
My gawd. I'd rather have open-heart surgery (done that) than be a slave of CPAP.

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.

tiltrider1 12-07-2019 08:30 PM

Quote:

Originally Posted by markpierce (Post 826727)
My gawd. I'd rather have open-heart surgery (done that) than be a slave of CPAP.

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/por...t-cpap-battery

markpierce 12-07-2019 08:40 PM

Quote:

Originally Posted by C lectric (Post 826728)
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.

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

Gee, my attempt to be sympathetic backfired.

C lectric 12-07-2019 09:07 PM

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.

JLD 12-07-2019 10:03 PM

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

Wayfarer 12-07-2019 11:03 PM

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:

https://www.batterypowersolutions.net...m-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.


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