How can I run a CPAP in my tiny van?

[BigT]

I did a search, but the only threads (3 of them) about sleep apnea or CPAP machines I could find were 2+ years old, so I'm starting my own.

Last week I was diagnosed with sleep apnea and put on a cumbersome and depressing machine.
I say depressing because I'm only 49 and in pretty good health otherwise. I'm not overweight, I don't drink, smoke or use drugs, and I exercise regularly.
Being hooked up to a machine at night to help me breathe, makes me feel like I'm 149 and dying in a hospital somewhere, hooked up to tubes and wires.

But I digress.

The unit, a "Respironics REMstar Auto A-Flex" is a 12 Volt/5.0 Amp system, so providing I can find a cord, I figure I can run it in a car at night. Thing is, I know nothing about calculating or installing electronics, so I'm not sure what I can safely run this thing off of.

I'd love to put an auxiliary deep cycle battery in my van that gets its charge from the alternator, but my Transit Connect is tiny so there's not much space for an additional car-sized battery anywhere (there's zero room under the hood). Is there a small/compact deep cycle battery that will work, and can it be mounted inside the vehicle?
I heard mention of using 12V golf cart batteries, but the ones I found appeared to be of a wet-cell design. Wouldn't that need venting to the outside?

Would a golf cart battery mounted inside a wooden box (inside the van), hooked up to a solar panel work for keeping the system charged, and would it be powerful enough to run the CPAP all night?
My concern with solar-only is that if there weren't enough sunlight one day, I could end up with a dead CPAP machine. :-/

Any and all advice would be greatly appreciated. :angel:

-T

 

[akrvbob]

While I prefer golf carts, you must buy them in pairs and it sounds like you don't have room for two. You can get them in AGM but they are expensive.

Probably a big (at least 100 ah) AGM 12 volt deep cycle battery is your best bet. It can be put anywhere, even on it's side. Any chance it could fit under the passenger seat on it's side?

A 250 watt panel on the roof and a connection to the alternator is probably enough except for extended cloudy days. Do you need stealth, does the panel ruin it for you? That would be the toughest part.
Bob

 

[Optimistic Paranoid]

Well, if you run a 5 amp device for one hour, that's 5 amp hours. Run it for eight hours, that's 40 amp hours.

The rule of thumb is that you never discharge a deep cycle battery below 50%. So you would need a battery with a minimum of 80 amp hours capacity.

Fortunately, ordinary 12 volt group 24 deep cycle batteries are usually around 100 amp hours, so one battery would be enough.

Search on Amazon for vented battery boxes. They're not expensive.

AGM batteries don't need a vented box, but are much more expensive.

Will you be driving daily? If not, you'll need to go solar.

Regards
John

 

[Canine]

Since you are severely limited on size, lithium, while expensive, may be the way to go. With the correct setup, you can use lithium charged by solar.

Your cpap machine has an optional battery kit that lasts (in real life terms) one night with the humidifier on, two nights with the humidifier off. You can choose lead acid (13 pounds) or the lithium ion (3 pounds)- both run about $300 each.

The size of either battery would work well for you with the lithium being the size of a hardcover book. You get 500 to 600 charges per battery, so every 20 months max you would need a new battery.

You could charge it at a friends house or at work during the day- ESPECIALLY the lithium one because you don't need to worry so much about tipping it over. I think the lead acid needs to be upright, but I may be wrong. The lithium one could be placed in a drawer with the cable sneaking out, but the lead acid is about 3 times larger. That is still a small battery, but not as diminutive as the lithium ion.

Both batteries take 4 to 6 hours to charge.

You can get just the battery kit for about $150 (ouch!) and supply your own battery. The solar charger is about $300 (ouchy again!). This stuff labeled "medical" is expensive!

You may need to get creative- someone may have a creative idea how to effectively charge a small, proprietary battery like the one available for a cpap machine.

I hope that helps. Not being able to breath is no fun!!

 

[GotSmart]

I had my battery set up before I plugged in my cpap, and just use a small 12v converter out of a lighter receptical. But my unit is an 18 volt. Take it to a Radio Shack and they should be able to set you up with the right eparts.

If you have the power available, the parts are simple. I am still working on my solar~~~ but I have 4 AGM240 6volt wired into the charging system. I have used my cpap for 2 weeks without driving, 4 weeks with short trips.

 

[offroad]

Seems like a lot of power to run that cpap. Will need to check mine in the morning and see what it needs.

 

[GotSmart]

It is enough power to run a refrigerator. First the solar panels go on. I got such a deal on the batteries... I could not resist. 4 batteries for the cost of one.

Battery Outfitters, surplus MODOT sealed units. I am glad I had the space.

 

[BigT]

You can get them in AGM but they are expensive.

Probably a big (at least 100 ah) AGM 12 volt deep cycle battery is your best bet. It can be put anywhere, even on it's side. Any chance it could fit under the passenger seat on it's side?

A 250 watt panel on the roof and a connection to the alternator is probably enough except for extended cloudy days. Do you need stealth, does the panel ruin it for you?

No, there's no issue with a solar panel. I've been wanting to mount one to my roof rack for a while now but wasn't sure what to get.
Why 250 Watt? Is there a Watt-to-Amp ratio I need to adhere to?
I was hoping to avoid the alternator, but only because plumbing the wires all the way up the van seems like a PITA.

Well, if you run a 5 amp device for one hour, that's 5 amp hours. Run it for eight hours, that's 40 amp hours.

The rule of thumb is that you never discharge a deep cycle battery below 50%. So you would need a battery with a minimum of 80 amp hours capacity.

Fortunately, ordinary 12 volt group 24 deep cycle batteries are usually around 100 amp hours, so one battery would be enough.

Search on Amazon for vented battery boxes. They're not expensive.

AGM batteries don't need a vented box, but are much more expensive.

Will you be driving daily? If not, you'll need to go solar.

Thanks for the simple math! :shy: My concern with venting is about whether or not I need to vent to the outside to avoid dangerous fumes inside the van. I'm trying to avoid cutting holes in the body. A better that doesn't outgas would be nice for that reason, and wasn't sure if AGM's suffered outgassing or not.

 

[cdiggy]

No. At truck

---

Ignore that^^^^

 

[BigT]

With the correct setup, you can use lithium charged by solar.

Your cpap machine has an optional battery kit. You can choose lead acid (13 pounds) or the lithium ion (3 pounds)- both run about $300 each.
You get 500 to 600 charges per battery, so every 20 months max you would need a new battery.
Both batteries take 4 to 6 hours to charge.

You can get just the battery kit for about $150 and supply your own battery. The solar charger is about $300. This stuff labeled "medical" is expensive!

I considered the Respironics battery pack at one point, but what I'd really like is a solar panel hooked to an AGM deep-cycle battery, and possibly a small power-inverter, that I can run/charge multiple items off of: CPAP, Macbook, cordless razors, a reading light over the desk, etc.
I am limited in space, but I'm hoping I can get away with a battery mounted inside a box, under the bunk.

You're right about stuff labeled "medical". The Respironics lithium battery pack/kit on Amazon runs $280.00 :s Yikes!!

It certainly would be easier to install, though.

 

[akrvbob]

I recommend a 250 because it's the cheapest panel per watt you can buy. Often a 250 will be the same price as a 140. However if you have too ship it you are better off with several small panels as shipping is very high on big panels.

I recommend it also because your health depends on it and you can be certain rainy days are coming. In that situation, better too much than too little! That's also why I recommend hooking up to the alternator.

AGMs don't out-gas and don't need to be vented.
Bob

 

[offroad]

Looking at my cpap label. It says dc 24v and 1.25a (fg) for a respironics resmed s9 model. That is of course without the humidifier. With humidifier it's 3.75a So you should be able to use two deep cycle batteries in series for 24volts. And then have it last a few days. Since you are only using the batteries 8 hours you will have 10amphours in 8 hours.

So you need two 12volt deep cycle batteries that have a 20amphour capacity. Because you only should discharge lead acid batteries half way for optimal life.

 

[AuricTech]

I would go with a larger battery bank than offroad suggests, simply to keep the depth of discharge down to 25% or so (75% remaining state of charge). That will help extend your battery bank's life.

Then again, it's easy for me to spend someone else's money....

 

[66788]

I you don't use the damn humidifier (which is nothing more than en electric heating unit) your machine will draw less than 1/2 amp. I run mine all night long with a 7 amp gel cell.

Personally, I don't like or use the humidifier, I find the normally dry air to be refreshing.

BTW, I have the same unit as yours.

 

[VanLifeCrisis]

I was gonna post about a luggable loo, until i reread the title more carefully

 

[offroad]

66788 - yep that is about right.

 

[BigT]

My Respironics doesn't have the humidifier system, so at least I don't have to deal with that draw. I just got a new CPAP from Kaiser yesterday. This one is still 12V, but the Amps are now 6.67. It's called a "System One", if that means anything to anyone. I sure wish it were a little smaller.

I've been reading other posts here on solar, and I kept seeing references to running two, 6 Volt AGM golf cart batteries in series. Is this just for space savings? One member says he's getting 205 ah from this system. Is there any disadvantage to running two, 6V batteries over a larger, single AGM battery? I'd like to save as much space as possible, so if I don't have to run a full-sized (car-sized) AGM 12 Volt battery to get optimal results, that would be great.

I don't want to spend $2,000 on my setup, but I can afford to invest some in quality parts. I've been burned many times in my past, trying to save as much as possible on things I've bought. Now I try to compromise (not too expensive, but not the cheapest crap I can find).

Also, can I buy solar panels in any dimensions I like, or are they pre-sized? I've got a Yakima rack on the roof of my van, but half of it is taken up by a set of kayak saddles, leaving me with an area 20" wide. Length is only limited to the length of the van.
I was thinking about mounting it via z-brackets to a piece of plywood.
Now that I think about it, my kayak is going to shadow the panels unless I park facing east or west. :/

 

[Optimistic Paranoid]

6 volt golf cart batteries are TRUE deep cycle batteries, unlike the so called RV/Marine batteries, which are an in-between hybrid. They can also be bought fairly cheaply from places like Sam's Club, but they are not AGMs, they are flooded lead acid batteries, and they will need venting outside your van.

Nobody custom makes solar panels, you have to buy a standard size off the rack as it were.

That said, A M Solar sells one panel that's only 21" wide. Their solar education articles are also excellent reads.

Regards
John

 

[BigT]

These wouldn't equal 250W, but would this suffice if I installed 2 of them?  

RENOGY 100 Watt Monocrystalline Photovoltaic PV Solar Panel Module 12V Battery Charging

Price: $149.99 & FREE Shipping.
High modules conversion efficiency. Ideal output: 500 watt hours per day (depends on sunlight availability).
Perfect design for your RV when camping or beach trips with the family.
Withstand high wind (2400Pa) and snow loads (5400Pa); resistant aluminum frame which allows the panels last for decades.
Excellent performance in low light environments.
25-year transferable power output warranty; 5-year material and workmanship warranty.

They measure 21" X 47" so I'm hoping to be able to install two of them lengthwise (8" long by 21" wide) so they don't take up as much room next to the kayak. 

I'd still have to figure out what control module and batteries to use, but it's a start.

 

[akrvbob]

You can buy the Renogy panels as kits that takes all the decision making out of it. Or as folding 100 watt suitcase portable kits that are plug n play which means zero installation.

Bob