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Old 06-07-2018, 12:36   #1
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CPAP power question

We're looking for advice on powering a cpap overnight. Our 30 ft. Cape Dory has two batteries (house and engine) plus a small solar panel. Running the CPAP on the house alone is not working. We don't want to switch to the engine battery as we don't want to deplete it. Does anyone have advice? We lack electrical engineering degrees so simple is good. Thanks for any recommendations.
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Old 06-07-2018, 12:54   #2
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Re: CPAP power question

I have been using a Resmed Cflex+ System One aboard for the last two years.
I bought a cigarette lighter adapter for it from Resmed, but I think I could have made it myself.

The main unit uses about 1ADC peak but the average usage is much lower than that.

It's the humidifier that uses a lot of power, but you don't need that on a boat.

So, if you were using a humidifier, turn it off, or disconnect it.

Otherwise your battery should be able to handle the load.
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Old 06-07-2018, 13:30   #3
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Re: CPAP power question

You need a bigger House bank, and or better / more charge sources.

If you're powering it through an inverter, going to a DC 12V direct "car adapter" would make a significant difference.

So does disabling non-essential functions like a humidifier.

And of course some units are just less thirsty than others.
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Old 06-07-2018, 14:01   #4
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Re: CPAP power question

Sumner had one. Might find it in his website:


Macgregor 26S Index
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Old 17-07-2018, 17:31   #5
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Re: CPAP power question

You need to calculate max wattage used, add the number of hours and then do the same thing for charging capability and be realistic in all the calculation.



Example: I spent this past winter in the Bahamas using my Resmed S9 Auto each night. I used a DC-DC converter to power the S9. The resmed uses 24 volts at 3.75 amps, or 90 watts. I used 100 watts for calculations assuming 90% efficiency. I ran it only off the house bank, which is 200 amp/hours. In the winter I slept from sun down to sun up, or 10 hours max. CPAP load per night was 1000 watts or 83 amps at 12 volts. On the charging side, I had two 315 watt solar panels and a 400 watt wind generator. The house bank was only charged by solar and wind. I also designed a charge optimizer which routs available charge sources to the battery bank in most need of charging.


Bottom line was I never ran out of power. The house bank powered everything all night long. Solar charging during the day and most nights I got some wind charging.
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Old 17-07-2018, 17:33   #6
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Re: CPAP power question

> CPAP load per night was 1000 watts or 83 amps at 12 volts.

I assume you mean watt-hours / AH.
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Old 17-07-2018, 18:29   #7
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Re: CPAP power question

The power required for my C-Pap machine is not constant. It varies from almost nothing to about 1A peak during inhalation. So the average power is quite low.
As I said before, I don't use the humidifier, don't think it's necessary on a boat.
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Old 17-07-2018, 18:42   #8
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Re: CPAP power question

Phillips Resperonics System 1, is a native 12VDC machine, when plugged into 120VAC the brick outputs 12VDC. The cigarette lighter kit for it is just a plug, no power conversions, so therefore it is very efficient, much more than most systems as they have to convert power. It is perfectly happy with voltages we have in our battery banks, it does not need exactly 12 V.
Good luck figuring power draw, itís all over the place as they are on demand machines, maintaining a constant pressure with variable rate, so power consumption varies greatly, and since you and I have different pressure settings, itís going to differ from one person to the next.
If you machine is an Apap machine (the system 1 is) use it, cause it will turn up the pressure as required to keep you from having Apnea and down and save power when you donít need it, plus low pressures are more comfortable as there are less leaks.
If you want a little humidification, put water in it, but leave the heater off, most of the power used, is used to heat the water, and you really donít need it on a boat.

Both of us have been on CPAPís for years and of course full time on the boat. I installed dual Blue Sea cigarette lighter receptacles beside our bed and power ours that way.
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Old 17-07-2018, 22:25   #9
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Re: CPAP power question

Have you talked with anyone about a mouth apparatus to move your lower jaw forward and open up the breathing passage. It solves snoring as well as sleep apnea for some people. The apparatus is an upper and lower retainer affair with tabs that hold the lower jaw slightly forward of its normal position. Has definitely worked for me, especially the snoring, but understand that it's not the case for everybody. My wife now sleeps soundly through the night and the jab bruises on my ribs are almost healed.
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Old 17-07-2018, 22:41   #10
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Re: CPAP power question

Quote:
Originally Posted by a64pilot View Post
Good luck figuring power draw, itís all over the place as they are on demand machines, maintaining a constant pressure with variable rate, so power consumption varies greatly, and since you and I have different pressure settings, itís going to differ from one person to the next.
AH counters can do this easily, overnight or per week, both load consumers and charge source contributions.

Cheap ones on eBay, or can use full-fledged BMs like Victron BMV, just put Andersons on the shunt to make it portable.
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Old 17-07-2018, 23:33   #11
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Re: CPAP power question

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Originally Posted by roverhi View Post
Have you talked with anyone about a mouth apparatus to move your lower jaw forward and open up the breathing passage. It solves snoring as well as sleep apnea for some people. The apparatus is an upper and lower retainer affair with tabs that hold the lower jaw slightly forward of its normal position. Has definitely worked for me, especially the snoring, but understand that it's not the case for everybody. My wife now sleeps soundly through the night and the jab bruises on my ribs are almost healed.


The ďmandibular advancementĒ appliances can be very effective for many people. They have about the same success rate as the CPAPs but for different reasons. The CPAPs work for almost everyone but only about 50-60% of patients continue to wear them. ( social reasons, dry mouth, claustrophobic, etc)
The mandibular appliances work for snoring and apnea for about 60% but patients donít mind using them.
You can try fitting yourself with one of the many options available over the counter or online to see if it is going to help but they tend to be bulky. You need to have who ever you sleep with confirm that you are not having any lapses in breathing while you sleep. If you think it may be an alternative to a CPAP then get a dentist that knows what heís doing to have one properly fitted to your mouth and adjusted as needed. Then go and have another sleep evaluation to confirm you are not having any issues at night while wearing it.
Before I retired I had made hundreds of them for patients that were unhappy with their CPAPs or wanted to go camping ,etc. but we were careful to have the evaluations post op.
No worries about power availability or battery drain but you do need to confirm itís suitable before you abandon the other.
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Old 10-10-2018, 02:22   #12
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Re: CPAP power question

Why you don't try to use alternative cpap machine like Winx Sleep Therapy is one of the critical alternative treatments for sleep apnea
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Old 11-10-2018, 05:43   #13
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Re: CPAP power question

I use Respironics autopap machine with humidifier at home. For boating and camping use I got a dc cord which cuts out the power loss of the transformer. A 35 amp-hour wheelchair battery lasts nights with no problem. A smaller lighter lithium ion battery is used by a family member. I only sleep about 6 hours and the autopap pressures are modest do your results may differ. You definitely need the 12 volt cord if you have a 12 volt machine. Stepping up to 110 with an inverter and then back down to 12 with the cpap power supply is doubly wasteful. Then it is just a matter of boosting your house bank, reducing other demands, or carrying a separate CPAP dedicated supply. I keep the wheelchair battery at home on a battery tender anyway for power outages.
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Old 11-10-2018, 05:44   #14
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Re: CPAP power question

Sorry. The wheel chair battery lasts three nights.
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Old 11-10-2018, 06:10   #15
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Re: CPAP power question

Quote:
Originally Posted by Myana View Post
We're looking for advice on powering a cpap overnight. Our 30 ft. Cape Dory has two batteries (house and engine) plus a small solar panel. Running the CPAP on the house alone is not working. We don't want to switch to the engine battery as we don't want to deplete it. Does anyone have advice? We lack electrical engineering degrees so simple is good. Thanks for any recommendations.
There was a lengthy thread on this a couple years ago you might find with a search.

There are some lower power options available in different machines.

There are travel machines with a battery pack made for overnight.

The humidifier increases power consumption.

If you can use the mouth plate it is zero power.

If you must run the O2 concentrator you might need a bigger battery.
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