CPAP Hook-up

Indiogoa

We recently purchased a 2018 TAB 400 and are eager to take it out camping. We are aware that when the trailer is not connected to shore power at the campsite, anything plugged into electrical outlets can't be powered up. This leaves a bit of predicament for using a CPAP machine which has to be used every night. 

Considering some very expensive options including buying a portable rechargeable CPAP battery or a portable generator. Has anyone else had this issue and developed an alternate solution to using a CPAP machine in the trailer in the event shore power is not available to power the machine? 

CrabTab

Look for a 12V power cord for your CPAP @Indiogoa (you didn't mention what brand you have). 12V power is available when you're boondocking.

dragonsdofly

@Indiogoa, does your 400 have an inverter? I may be incorrect, but I believe that is/was standard for all 400's. An inverter converts battery power to 110/120 AC household current. Although it is a very inefficient use of your battery reserves, you can power limited wattage items from it. Another possibility, 12v cpap's are available for purchase, although I don't know about costs involved. There have been discussions here on the forum about this very thing. Use the search function on the upper right hand side of your screen and use a key word or 

VictoriaP

I am not a CPAP user, but my late husband was, and we went through this for him for emergencies such as lengthy power outages. 

First, be aware that running a CPAP directly via a portable generator may not be the solution. Many campgrounds have banned their use overnight. And most only run 6 or so hours on a tank of fuel, not a full night’s sleep.

Start by googling your exact CPAP model. Some have 12v power cables available for purchase, and recommendations on exactly how to configure for 12v usage (such as turning off the humidfier). Running directly on 12v rather than converting 12v to 110 (via an inverter) uses less power, which means your battery lasts longer. If this is an option with yours, it’s the first choice. You can plug directly into the trailer’s 12v system.

Second choice is get an inverter of the correct size, connect to trailer battery, plug CPAP into inverter. You’ll need power usage specs for your CPAP to determine the inverter size needed.

With either of these, you will still need to be able to recharge the trailer battery, preferably daily, via solar panels or portable generator. Again, whether or not a generator is a good purchase is entirely dependent on where you camp. If you’re somewhere you can only use it a couple of hours a day due to noise regulations, it may not be able to fully charge your batteries if you’re a heavy power user. 

In my husband’s case, we had a “solar generator” (stupid name, since they don’t generate anything) to power his. These are basically a battery and inverter in one, and you still need a method to charge it (I use a 100w portable solar panel or a tiny 900w propane generator) but they’re usually good for several nights depending on size. Goal Zero and Jackery are two common brands.

Bayliss

@Indiogoa, I used a Medistrom portable rechargeable power supply for my CPAP.  It is thin and easy to store.  It usually lasts two nights before recharging and has an alarm that alerts you if the power is low.

pthomas745

Find out how big your battery is.  How many amp hours do you have to use?  

Find out how many watts your CPAP uses in the different modes.  (I know little about them, except what I read on these forums.)

When you know those things (or have really good estimates) you can begin to make good guesses about how much power you will need to run the equipment and how long your batteries will last. 

And, welcome to the Forums!

Here are other threads that have discussed CPAP and battery use.

https://www.google.com/search?client=firefox-b-1-d&sxsrf=ALeKk02uEjhrXwymol0rWI6p888KY19QKQ:1588887973724&ei=pYG0XqvoK46esQXZipVo&q=cpap+site:tab-rv.vanillacommunity.com&oq=cpap+site:tab-rv.vanillacommunity.com&gs_lcp=CgZwc3ktYWIQA1CAEFjWJWCdMGgBcAB4AIABxgGIAYARkgEEMTUuNpgBAKABAaoBB2d3cy13aXo&sclient=psy-ab&ved=0ahUKEwjrzov63KLpAhUOT6wKHVlFBQ0Q4dUDCAs&uact=5

Cbusguy

Lots of opinions here.      The low dollar solution is to purchase the correct cigarette lighter adapter for your cpap machine.     The cost from $15-100 depending on the machine.

This will allow you to run regardless of AC power or not.     

Running a generator overnight is not very neighborly and is prohibited by most campgrounds and running it off the AC inverter......is just bad advice, as it is incredibly inefficient. It wound most assuredly kill a 100 amp hour battery overnight if off grid

Been camping with cpap 20 years......my recommendation is tried and works just fine

ColoradoJon

Right, running on a AC inverter would be expensive power wise.  I found a discussion about CPAP power usage through a google search, and someone used a Kill-A-Watt power meter to test the cumulative power consumption of their CPAP machine over 4 1/2 hours.  The machine averaged 150 watts during the test period.  Here is the link to the discussion at cpaptalk.com (from 2012):  Measured CPAP power consumption

Converting that to 12VDC:
150 / 12 = 12.5 amps used per hour

Used for 10 hours = 125 amps
Add inverter efficiency loss of 12% = 140 amps required per day

To support this with solar:
300 watt pure sine wave inverter (or modified sine wave if your device supports it)
280 amp battery bank (includes 50% DOD cap)
400 watts of solar panels (includes charge inefficiency loss of about 20%)

Not sure if you can get a 12V cable for you machine as others have stated.  It will probably use less power, but you will definitely need to do the calculations either way.

CrabTab

Had a few moments to take some photos today and update my previous thought on this discussion...

Here is a photo showing the 120 VAC and 12 VDC power cords for a Phillips Dream Station CPAP. The 'brick' on the standard AC cord is a transformer the changes standard house 120VAC to 12VDC for the CPAP. The machine actually runs on 12VDC power, so you aren't harming the machine in any way to use a direct 12VDC power cord. The 12V cord accessory costs about $30 online. As others have noted, it plugs into one of your 'cigarette lighter' jacks.



I believe the actual amount of energy you'll use is dependent on:
1. use of humidifier (uses more energy)
2. unit pressure setting for your needs
3. number of hours of use each night

Below are some photos of a 12VDC power supply we made some time ago for hurricane and tent camping use. It uses a 30MM plastic ammo case (<$5 at Harbor Freight), two 8AMP, 12VDC batteries (free with Cabela's points or about $30 each when not on sale) and a marine rocker switch panel with on/off, Volt meter, USB and 12VDC jack (about $20 online). 



This little unit provides several nights of power to a CPAP with no humidifier attached. For the calculator jockeys out there, this information is based on actual use. And no, I haven't hooked up the CPAP to a Watt meter or Ammeter. 

Sharon_is_SAM

Here is a very relevant thread.  https://tab-rv.vanillacommunity.com/discussion/comment/130116#Comment_130116

I think consensus is - buy the adapter and forget the inverter.

rcuomo

Agree with consensus, buy 12 converter if available. But I ran a Resmed machine for two days using a 200w inverter and an Interstate Marine 88Ah battery recharged by 100w Renogy suitcase. 

Indiogoa

Thank you all for your insights, lots to consider. Interestingly, the Phillips DreamStation Go which is a travel unit is setup to run off AC power only. The other alternative is to use the full size Dreamstation used at home which I believe does allow for a DC connection. The alternative is to buy a Phillips power source for situations when we are rarely boon-docking or lose shore power overnight. The 12 volt cigarette lighter outlet in the trailer is something I am studying using a portable 110 inverter, 300 Watt capacity just not sure if this will work to power the CPAP machine or/ and also totally drain the trailer battery overnight.   

pthomas745

A quick look at the web says the Dreamstation Go comes with a 80 watt power supply.  That would be the maximum the unit could draw.  It would work with a 300 watt inverter just fine.  80 watts divided by 12v equals 6 amp hours.  Over 8 hours, that would be 48 amp hours from your battery.  (Add about 15 percent for the efficiency loss of the inverter, etc.)    This would be the maximum it could draw......I know there are different settings that might reduce the power use. 

I think I could become a You Tube star with videos of different appliances being operated while being tested with a Kill-A-Watt. These things would be so simple to measure.

So:  how big is your battery?  You won't be able to start to figure this out with out that number.

Crab Tab's battery box is a beauty....I carry a small 30 amp hour battery in a box to run/charge my laptop and other things in the trailer.  A little extra battery like that is an excellent, inexpensive option for running extra devices.

CrabTab

@Indiogoa, I highly recommend the factory 12VDC power cord for your full size  DreamStation. It is under $30 on Amazon.

https://www.amazon.com/Philips-Respironics-Shielded-DC-Cord/dp/B07G7HZRH2/ref=sr_1_8?crid=CU8E2GQMVSPS&dchild=1&keywords=dreamstation+12v+power+adapter&qid=1589146959&sprefix=dreamstation+12v%2Caps%2C144&sr=8-8

A good way to learn your needs is to camp in your driveway overnight with a fully charged battery. You know you want to sleep in the camper anyhow (many of us are guilty of this act)!

When you get up in the morning, see how much battery you've used. This will give you a start on figuring out your battery needs. From there you can determine if you need to augment your electrical supply while boondocking.

Indiogoa

Great idea Crabtab, I was thinking about sleeping in the camper in our driveway and figuring out how much it drains the battery overnight. As far as knowing what battery is in the 2018 TAB 400, its a single battery before they switch to two 6 volt but I have to remove the cover to get all the information off the battery, this information should be in the user manual....  

PTthomas745-If I use the Dreamstation Go, I'll be looking at buying the  portable inverter 300W but I think the 12V DC cable hooking up the fullsize Dreamstation seems to be the more cost effective option at this point. 

pthomas745

@Indiogoa The single large battery is big enough to handle the 48 amp hours for one night, at least.  So, any reduction of that number of amp hours would work out for you quite well.

Cbusguy

@CrabTab that seems the only way I will get to camp for the next couple of months.

Homebodyatheart

I’ve got the larger Dream Station and it is built to be able to remove the rear section with humidifier, etc. This will cut your power need, and the 12v cord works just fine, too. 

ColleenD2

I know this conversation is older hopefully someone will reply but to clarify, are you saying if I have the cigarette lighter cord, my husband can use his Cpap when we aren’t plugged in and it won’t drain the battery. 

He finds he doesn’t need the humidifier in o7r T@B 320. We don’t have a way to test as we store off sight.

I read all these numbers and my mind explodes. Lol

techietab

ColleenD2 said:

I know this conversation is older hopefully someone will reply but to clarify, are you saying if I have the cigarette lighter cord, my husband can use his Cpap when we aren’t plugged in and it won’t drain the battery. 

Short answer: no. It could drain the battery. While a CPAP on a 12v DC power adapter is unlikely to exhaust a stock 100Ah 320s battery within a night or two (probably even three) if running on its own...you will almost certainly be expending battery power on other things too. 

As others have recommended, the safe bet here is to go with a portable battery pack and test it at home to figure out how many hours of use you can get out of it. For instance, I use an Anker PowerStation rated for 778Wh (or ~65Ah at 12v, if you want to compare apples to apples here) and know from testing at home that it will power my travel CPAP (Resmed Airmini) for 4 nights.

pthomas745

It will "use battery power".  How much depends on the device.  "Drain the battery" is totally relative to how much power it uses, how big your battery is, etc.  I use items in my 12V ports either with their own cords or an inverter.  As long as I know the amp hour/wattage of the items, and how much power I have to use, I never "drain the battery". 

ColleenD2

I wish I knew what the heck I was talking about and no matter what I read when it comes to numbers, even simple math, my anxiety takes over.

I’m just going to keep asking until it clicks or someone does my math please. 

And what do I mean by drain the battery? Heck if I know. I want to be able to make it home and not have to replace it? I don’t want to ruin it? I don’t want to take it to the point of no return?  I know a s-ton about this camper but the battery eludes me. We have the 

We won’t be using the fridge because we have a bear safe cooler that will be in the car. We won’t be using the TV or charging any devices. We could even live without the lights since we have headband lights. We are already winterized so we won’t be using the water pump and I love to be cold so we won’t be running the Alde. Let’s hope it’s cool in the mountains and no crazy summer heat wave. 

Our battery is from the dealer and it’s an Interstate 12v Deep Cycle AGM Group 24 Battery.

We had the Victron thingy, please don’t ask what because I don’t know at this second, when we ordered the custom T@B. I understand it is standard now. We use this to monitor the battery.

We are going to be without power for 8 consecutive nights. 

We have solar on the T@B but no idea how much shade we will be camping under. 

We can carry things to the ranger station or other places in the world to charge. 

We won’t be hanging in the camper during the day.

His Cpap is the Older REMstar Plus CPAP machine. It comes apart so you don’t even need to bring the water section. We do own the 12v cord and that is what he currently uses because that’s what easy and on his side of the bed. He doesn’t use the humidifier with it in the T@B, he finds he doesn’t need it. 

I found this info on the web but it doesn’t make it true but here ya go.
“I've done measurements on the REMStar Auto running on dc. It draws about 0.75 amps, which corresponds to 9 watts (12 x .75) without the humidifier.This is about 1/6 of the power of a 60 watt light bulb!”

We also own this for his telescope but maybe we can use it instead of buying another battery pack? Any thoughts? Anyone willing to do the math for me?
https://www.meade.com/meade-lxps-18-lithium-portable-power-supply.pdp

Thanks again for your help with this. It’s times like this I really miss Bob. He was so great at explaining and walking you thru things. Hi in heaven to you Bob! 

GigHarborTom

 I have been married to a CPAP for over twenty years while trailer camping. I have, and replace every few years, a what I call a jumper box. They have a small compressor, emerg light and jumper cables. I have used all features. They have a 12V outlet and last at least three nights if kept charged up. When off grid I will use the on board battery, with frig turned up or off at night, etc.  When I really want to save energy, I'll use  the jumper box a couple nights and then go for on board power.  This little thing has been used to jumper a couple stuck class A motor homes, air up a tire in an emergency. I use it when tent camping with my Mountain Man events.  Just can't bring myself to pay the big bucks for more than this. I recently bought a solor suitcase. Used once just to try out. Not convinced it was worth it.

pthomas745

Ok...we have one number!  Your Group 24 80 amp hour battery.  You can use 40 of those "amps"...which is 50 percent of its capacity.  This will protect your battery to keep you from ruining it.

The Victron "thingy" is the Victron app.  The most important thing you can do to protect your battery is..to know what the battery "state" is.  Your "app" is like the gas gauge in your car.  Imagine driving a car with no gas gauge.  The app is your best friend when trying to figure out where you are in "battery fuel".

If you don't plan to use the fridge at all....you are in pretty good shape on how many of those "amps" you can use.  The fridge would be your biggest power user, so this will save you plenty of "amps".

All the items in the trailer have been measured by much smarter people than I, and we have a really good idea of how many "amps" they use.  The bedside "reading lamps?"  1/10th of an amp.  In 10 hours...they would use 1 amp.  The television uses 1 amp or so.  In 10 hours, it would use 10 amps.  And, so on.  In fact, without using the fridge, you would have a difficult time using 40 amps in a day, unless you liked watching TV all night.  The trailer is very efficient.  Your "not using your fridge" helps you out quite a bit.

Your solar setup is also important.  The more "good sun" you can get on the panel, the better it will recharge your battery.   If you have used only 10 amps during a 24 hour period, in full sun your panel may replace those few amps in 4 hours (estimated!).  If you are partially shaded, it might take longer.  Again: the Victron app is your friend.  It will show you how much solar energy is hitting the panels, and you can see your battery state of charge.

PS: phones and small devices that can plug into the 12V ports use very little power to charge, also.  Laptops will take a little more to charge. 

Your CPAP: most of the CPAP info I've found show the systems without the humidifiers use less than an amp to run on the lower pressure settings.  The only info I can find on the REMStar Plus power usage is from the manual, which says it uses "3 amps" maximum.  That would be, most likely, at the highest possible power settings. 

Are you comfortable with looking at the Victron and figuring out what it is trying to tell you? It will be your most important tool on your trip.

PS: We all miss Bob P!

PSS: please ask questions.  Post your Victron status screens.  Many people here can help you decode it all.

P.S.S.S   That Meade battery pack is...a battery pack.  Like the other "extra" batteries mentioned in the thread.  It says is has an "18AH" capacity.  A lithium battery can use 90 percent of its amp hours.  That would be a good extra battery for your CPAP, and, if the CPAP power use is as low as we think it is, it might get you a couple of nights of use.  You would need a way to recharge it...if you have the "cigarette lighter power adapter" you can plug it into one of your car plugs while driving and give it a charge.

GigHarborTom

I ran without humidifier for most years. Do now, and being heated does make a difference for more comfort cold weather.

ColleenD2

Thank you!  I feel like I’m finally getting somewhere! I almost get it hahaha. 

We do keep an eye on the Victron. We never let it get below 12.51. Bob shared this and said it was better to follow Nick‘s chart.

http://popupbackpacker.com/state-of-charge-your-camperrv-may-be-killing-your-battery-bank/

pthomas745

You will never see a state of charge of a rested battery like yours at 12.91.  Stick with the plain old ordinary state of charge chart that says 50 percent is 12.01.  If you stop using power when you see 12.51 on your Victron, you are basically using only 8 of your 40 usable amp hours. Your trailer battery will not see 12.5 after the first 8 amps you use from your battery. 

Lots of good basic info on what to look for in a battery on that site, though.

ColleenD2

Thank you!