Powering Cpap machine without electrical hook-up

[ANDY THOMPSON]

We camp via a 2006 Rockwood popup, typically in state campgrounds without an electrical hook-up. We have (2) deep cycle batteries on the camper and have added an Inverter to power my Cpap. With the humidity option turned off I can usually get 2 -3 nights without recharging the batteries via our tow vehicle. We have some longer trips planned and I am wondering what others do to get more nights of operation without a generator or recharging the batteries.

 

[J Starsky]

@BikeNFish has a metric ton of good posts on this very topic. IE: batteries, generators, Jackery stuff - he's used it all. You should search his name up top ^^^

 

[davido]

Do you know the consumption per hour? If you're getting 3 nights and depleting the batteries down to 40%, and they're two Group 24 deep cycle batteries, you're using about 90AH, or 30AH/night. If you're asleep 7 hours, then 30AH/7=4A or 5A per hour.

Conservative estimate: 5A/hour. And 30AH per night. If that's your only load, you can get a net neutral consumption from about 150W of solar. To play it safe, install two 100W solar panels and a charge controller for them. That will give you a net-positive most days.

Solar panels aren't small. But most popups ought to be able to handle having a couple of 100W panels on the roof. And with 200W total, you should be able to stay ahead of consumption even with the high load of running CPAP all night every night. I do think that 100W would be inadequate.

Or run a generator 4 hours a day.

 

[LilRed]

Best investment I made was a 12v DC-DC plug for my CPAP from the mfg. The Inverter option is majorly inefficient in comparison. I haven't dry camped since getting the new power brick, but I do use it regardless of having Shore Power. I figure if the 120v goes out, at least the 12v will keep it on and me breathing...

 

[Econ]

without an electrical hook-up.
(2) deep cycle batteries
added an Inverter
humidity option turned off
2 -3 nights longer trips planned
without a generator or recharging the batteries.

In the Deep South we have a heavy tree overcast hence no solar option after leaf out.. If going out west you can use solar. Without solar its a generator or 120 vac. Done been down this road. Also it depends on how long you will be at one campsite. You could use an DC/DC charger on your TV if towing between sites. There are no other options except running TV for a hour.

How big are your batteries.? why not get twin 225 GC? At least you will have 112 amps available @ full charge.

We have bribed the camp host to use their 120vac.

>>>I am wondering what others do to get more nights of operation without a generator or recharging the batteries.<<<<< Aint happening

@davido
<<<<4A or 5A per hour.<<<
to confirm your estimation.
130 AH battery * 50% = 65 Amp
I'm lucky to get 2.5 days with minimal other use. (refrig controls) ( 40%
discharge in 2 days.)
OEM Power center has "max output" at 5 amps.
DW has turned all the bells and whistles off.
This CPAP in about 10 years old. 8 or 9 ish hours/night = 26amps =3ish amps/hr. plus that is about 50% of what the power center puts out.

 

[SteveP]

Best investment I made was a 12v DC-DC plug for my CPAP from the mfg. The Inverter option is majorly inefficient in comparison. I haven't dry camped since getting the new power brick, but I do use it regardless of having Shore Power. I figure if the 120v goes out, at least the 12v will keep it on and me breathing...

He's right. Most cpaps run on DC, if yours uses a wall wart or power brick it definitely runs on DC. The power brick looses some power in the conversion to from AC to DC, I'll be generous and say 10%. Unless you have a very expensive Inverter your probably loosing 20% in the conversion from DC to AC. So that's a minimum of 30% loss using the Inverter.

And surely the cpap is not the only thing you're running on the battery. So to reliably go more than 3 days you're going to need some sort of charging ability. Charging from the TV is the least efficient way to go. Solar panels are the most efficient but they do have some limitations.

Let us know what cpap you're using, and the brand and size of your batteries.

 

[Bradley E Dixon]

Both my wife & I have /need CPAP machines.

I added another 12v DEEP cycle battery and re-wired the camper itself with new 12 plug-in and USB 2.0amp charger ports at both bunks.

I did some serious research on the whole amp/hr capacity/draw when using a CPAP and also found the CONS of using an after-market Inverter.

The CPAPS electronics are pretty sensitive to the correct voltage SINE wave, and the el-cheapo inverters operate on the SINE wavelength called MODIFIED that is NOT recommended.

If you're going to use an Inverter you need one that produces PURE SINE and they tend to be pricey.

So I also purchased 12 DC factory travel adapters for both machines, and use the 12v plug I wired in, to power the units.

So the "dirty" power issue out of the way I also researched on both machines the amp/hr draw per machine on the "low humidity setting". Added them together. Compared the combined amp/hr output capacity of my combined 2 deep-cycle 12 batteries ....... and ended up with a 10hr window of continuous power for the machines.

Overall I'm pleased with the results.

My2cents

 

[davido]

In the Deep South we have a heavy tree overcast hence no solar option after leaf out.. If going out west you can use solar. Without solar its a generator or 120 vac. Done been down this road. Also it depends on how long you will be at one campsite. You could use an DC/DC charger on your TV if towing between sites. There are no other options except running TV for a hour.

How big are your batteries.? why not get twin 225 GC? At least you will have 112 amps available @ full charge.

We have bribed the camp host to use their 120vac.

>>>I am wondering what others do to get more nights of operation without a generator or recharging the batteries.<<<<< Aint happening

@davido
<<<<4A or 5A per hour.<<<
to confirm your estimation.
130 AH battery * 50% = 65 Amp
I'm lucky to get 2.5 days with minimal other use. (refrig controls) ( 40%
discharge in 2 days.)
OEM Power center has "max output" at 5 amps.
DW has turned all the bells and whistles off.
This CPAP in about 10 years old. 8 or 9 ish hours/night = 26amps =3ish amps/hr. plus that is about 50% of what the power center puts out.

Ok, my estimates weren't too far off (they really were guesses).

OP may be able to get away with a 100 watt solar panel, but 200 watts of panels will put him in a much better place, particularly if the weather results in less solar charge efficiency. Putting two 100w panels on the roof of a pup is not an excessive amount of weight. And it should get the OP into a position where he's running a net positive each day, and therefore, could camp just about indefinitely.

I have a single 100w panel on mine. But I don't have any crucial needs. Mine are all comfort and convenience. I like the convenience of a water pump and lights. I like the comfort of the vent fan and furnace. I prefer the convenience of using the built-in fridge (which has its own vent fan) instead of only using my big cooler. And I prefer the convenience of being able to charge my cell phone in the trailer. My energy requirements even to maintain these levels of convenience and comfort are lower than the requirements of someone who must have CPAP. So 100w is fine for me, and a 100w panel, under typical conditions, should allow me to camp indefinitely. The OP's requirements are more energy intensive, and they're more vital. So 200W is worthwhile.

 

[kudzu]

Here’s another vote for a 12v power cord suitable for your particular model of CPAP. This is what we used for my Dad’s CPAP on a cross country trip. It was much more efficient. I installed a 12v “cigarette lighter“ style outlet wired to the converter box. That worked well. However, one we used a jumpstart box that has a 12v outlet built in. It isn’t high capacity but still ran the CPAP for about 6 hours.

I use a portable, suitcase style, 100 watt solar panel to charge when we don’t have hookups available. This usually works better for us than a panel on the roof. This way I can park the camper in the shade & place the panel it in the sun.

 

[SteveP]

OP hasn't been back since he posted. Never even read the first response.

 

[ANDY THOMPSON]

He's right. Most cpaps run on DC, if yours uses a wall wart or power brick it definitely runs on DC. The power brick looses some power in the conversion to from AC to DC, I'll be generous and say 10%. Unless you have a very expensive Inverter your probably loosing 20% in the conversion from DC to AC. So that's a minimum of 30% loss using the Inverter.

And surely the cpap is not the only thing you're running on the battery. So to reliably go more than 3 days you're going to need some sort of charging ability. Charging from the TV is the least efficient way to go. Solar panels are the most efficient but they do have some limitations.

Let us know what cpap you're using, and the brand and size of your batteries.

Thanks for the good info. Had a family reunion the past several days which kept me from looking at the site. I am using a ResMed Cpap and I do believe it is running on DC. Based on the info received I think I will get their 12v cord & battery and make changes to go DC all the way. Will likely keep the Inverter to charge phones, etc. Thank you!

 

[ANDY THOMPSON]

OP hasn't been back since he posted. Never even read the first response.

Steve - had a very busy few days since the post hosting a family reunion - on it now -- thanks for keeping me on my toes

 

[ANDY THOMPSON]

Do you know the consumption per hour? If you're getting 3 nights and depleting the batteries down to 40%, and they're two Group 24 deep cycle batteries, you're using about 90AH, or 30AH/night. If you're asleep 7 hours, then 30AH/7=4A or 5A per hour.

Conservative estimate: 5A/hour. And 30AH per night. If that's your only load, you can get a net neutral consumption from about 150W of solar. To play it safe, install two 100W solar panels and a charge controller for them. That will give you a net-positive most days.

Solar panels aren't small. But most popups ought to be able to handle having a couple of 100W panels on the roof. And with 200W total, you should be able to stay ahead of consumption even with the high load of running CPAP all night every night. I do think that 100W would be inadequate.

Or run a generator 4 hours a day.

Thanks - I will look into this - we typically camp in wooded state campgrounds, but do have some plans to be in the southwest which may work better with the solar panels

 

[Econ]

am using a ResMed Cpap and I do believe it is running on DC.

DW's CPAP has a power center that converts 120VAC to 12 VDC. It's a Resmed. It plugs into the CPAP. Took it down to electronic parts store and told them I wanted to plug this into a 12 VDC or hard wire to a 12VDC. For 10 or 15.00 they sold me the parts and told me what to do. Its hardwired and works great.

wooded state campgrounds,

One of my winter projects is to mount twin 100 watt solar panels on the TV roof, temporarily to charge a battery while parked at trailheads. It was AUgust project but DW wants a room painted.

 

[Haybale]

I also have the 12v adapter, as my CPAP runs on 24v. So going from 12v DC to 110v AC to 24v DC wastes a lot. 12v DC to 24v DC is better.

I have one of those jumper packs with an air pump and such built in.

I can go 2 nights (airplane mode, heated hose and humidifier off) per charge.

I simply plug a 50w flexible solar panel into the 12v socket during the day and have gone 12 days before.

It does come with a male to male 12v socket cord to charge with the TV if needed.

I had a spare car battery I used for a while, I went 5 nights on it. I don't recall the size but it is far a Saturn SL2 1997.

 

[ANDY THOMPSON]

Thanks for all the great info and ideas. We decided to purchase a Jackery with (2) 100 watt solar panels and bought the ResMed DC/DC converter. I charged the unit fully and have been testing various ways of using the Cpap and the energy usage. First night I used the Inverter option of the Jackery - used 19% of battery (7 hours) and had to put up with a fan like sound on and. off all night. Second night I switched to the DC/DC converter and used 11% (7 hours). The third night I did the same, but turned off the humidity and heated hose and used just 7% of the battery! I think I should be able to get about 10 nights of Cpap use before needing to charge which will be great. I post again if things change

 

[dbhost]

After my jump starter pack failed during the February 2021 Texas deep freeze / no power, I built my own battery pack. NOCO box for a group 27 deep cycle battery, an Oreilly deep cycle group 27 RV battery, and 2 12V socket, dual USB chargers and voltometers with switches, so I can independently switch each panel, Everything is crimped with heat shrink crimps and waterproofed, charging is done via my old B&D auto battery charger and HF Tailgator generator.

I have a Z2 travel CPAP with a humidity recirculator not a humidifier, it was designed and built for minimum power usage.

I started with just the battery, a 12v socket, and some alligator clips to get things going. The Z2 ran for a full week before power was restored with no need for charging of the battery. I was still at 12.7v resting.

Long term goal is 300w solar charging...

 

[Patty Crosson]

After my jump starter pack failed during the February 2021 Texas deep freeze / no power, I built my own battery pack. NOCO box for a group 27 deep cycle battery, an Oreilly deep cycle group 27 RV battery, and 2 12V socket, dual USB chargers and voltometers with switches, so I can independently switch each panel, Everything is crimped with heat shrink crimps and waterproofed, charging is done via my old B&D auto battery charger and HF Tailgator generator.

I have a Z2 travel CPAP with a humidity recirculator not a humidifier, it was designed and built for minimum power usage.

I started with just the battery, a 12v socket, and some alligator clips to get things going. The Z2 ran for a full week before power was restored with no need for charging of the battery. I was still at 12.7v resting.

Long term goal is 300w solar charging...

FYI -as a CPAP user you may be interested in this recall: https://www.fda.gov/medical-devices...-machines-recalled-due-potential-health-risks

 

[gogocamper]

We camp via a 2006 Rockwood popup, typically in state campgrounds without an electrical hook-up. We have (2) deep cycle batteries on the camper and have added an Inverter to power my Cpap. With the humidity option turned off I can usually get 2 -3 nights without recharging the batteries via our tow vehicle. We have some longer trips planned and I am wondering what others do to get more nights of operation without a generator or recharging the batteries.

Take a look at a Jackery portable power station. We have two mainly for our CPAP machines when boondocking. They work great, especially if you use a 12 volt adapter.

 

[K_and_I]

My DW and I both use CPAPs. We usually try to stay at campgrounds with at least electrical hookup at our destination, but often have to boondock on the trip out and back. I got a sealed lead acid battery that I keep in the passthrough compartment of our camper and wired it to 12v plugs for us both. In the morning before leaving for the day, I put the battery in the back seat floor of our truck and connect it to a 1.5A maintainer type charger which is plugged into the 120v outlet in the truck. Before I had a truck with a 120v outlet, I used an Inverter plugged into the 12v system in the truck. By mid afternoon, the battery is fully charged and ready for the next night's use.