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Dreamstation powered off of a car battery?
#1
Dreamstation powered off of a car battery?
Hi Folks,

I've been reading all the posts on camping with a CPAP. I'm going camping in a month or so and my plan was to use my dreamstation without the humidifier powered off a car lighter adapter plugged into our Honda CR-V. I read a number of posts on the adapter and motorcycle batteries and such but I couldn't quite translate the responses to a car battery.

So based on your expertise, how long can a Dreamstation run on a car battery? I'm guessing that after two nights use I'd still have enough charge to start the car on day three but wanted to touch bases with anyone that had more experience on the subject.

thanks for your help.

Jim
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#2
RE: Dreamstation powered off of a car battery?
Car batteries are not typically designed to provide power over a long time (bucket with a hole in the bottom that drips slowly). They're designed to drop a lot of current all at once (dumping bucket over somebody's head). Number and thickness of plates.... Not saying it won't work, but...

Deep cycle is probably a better approach, and a smaller one would likely run two nights guessing 18-24 AH 12 V). But just blindly guessing..

Don't know your pressures nor machine settings, but a 35 AH machine will run my Respironics System One auto 560 for around a week (8-ish nights) without the humogrificator running. As always YMMV>
There.  I said it.

OMMOHY
Contrarian in Residence  
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#3
RE: Dreamstation powered off of a car battery?
Thank you, OMyMy! I appreciate the response.... The boat my fishing buddy owns is driven by electric motors... I'll talk to him about the batteries used in the boat for my trip. 

Thanks again. Appreciate the help.

Jim
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#4
RE: Dreamstation powered off of a car battery?
A 17-18 AH battery would likely weigh around 12 pounds. My 35/39 AH batteries weigh about 24-25 pounds.

If you're thinking of borrowing a boat battery, they're way bigger and way way heavier. If you could put it in a vehicle and not have to move it around, that may be OK. But it may also be a wet battery (like a car battery you can add water to) which is a whole other kettle of fish. harder to transposrt safey, can spill, can vent bad (sometimes explosive) gas if overcharged.

The batteries I'm talking about are the SLA - sealed lead acid - or AGM - absorbed glass mat) -often a term used interchangably. These can be used in any position and do not spill.

If you acquire one, you also need to think charging solution. I have taken to the NOCO Genius smart chargers as of late. I used the Deltran battery tenders for years, and they're still good. The NOCOs offer a newer level of technology and some flexibility WRT charging modes (plain lead acid vs SLA/AGM and cold temp charging, or even lithium batteries.

In any case, if you get a decent sized battery, and keep it maintained, it will be an excellent emergency backup in the case of power failure.
There.  I said it.

OMMOHY
Contrarian in Residence  
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#5
RE: Dreamstation powered off of a car battery?
(08-26-2019, 03:54 PM)jimcaffey Wrote: Hi Folks,

I've been reading all the posts on camping with a CPAP. I'm going camping in a month or so and my plan was to use my dreamstation without the humidifier powered off a car lighter adapter plugged into our Honda CR-V. I read a number of posts on the adapter and motorcycle batteries and such but I couldn't quite translate the responses to a car battery.

So based on your expertise, how long can a Dreamstation run on a car battery? I'm guessing that after two nights use I'd still have enough charge to start the car on day three but wanted to touch bases with anyone that had more experience on the subject.

thanks for your help.

Jim

There are car power 12v to 110 AC inverters available that you can plug into the 12v cigarette lighter socket. Just get at least 150 watts because the dreamstation w/o humidifier uses a 65 watt power brick. You won't have a problem if you keep your engine running (thus constantly charging your battery) while you use your dreamstation that is plugged into the inverter.

As to your question on how long a dreamstation can run on a car battery alone, it would depend on the capacity of the car battery. To find out the capacity of the car battery, you have to compute the wattage that the 12v car battery can provide by multiplying the Amps with the Voltage (Amps x Voltage). If for example you have a 40Amp battery, your car battery will have a wattage of 480WH (40 x 12=480). Then you simply divide 480WH with 65 (the wattage required to run the dreamstation w/o humidifier) and you'll get around 7 hours in theory. However this will completely run down the battery and you won't be able to start your car. Plus this does not take into account the age of the battery, temperature, chemistry, etc. which will all impact the performance of the battery.
hearsay73
Hosehead padawan 
Repaying my sleep debt, 1 night at a time...
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#6
RE: Dreamstation powered off of a car battery?
Inverters are a VERY bad idea. Primarily intended as an AC source for using household appliances while going down the road, not parked and running off battery.

Far Far better, if you have to run off a battery in a car, is to get a direct DC connection. CPAP manufacturers often offer them. Inverters take 12 v, but burn a bunch of power to convert to 120 V AC, which your power brick turns back in to 12 V (maybe 24 if you have a Resmed). That's like needing to go from the bedroom to the kitchen by walking past the kitchen, going out to the car, driving around the block, then coming back into the house and walking to the kitchen.

And you can't just say it's a 65 W coverter and go there. Look at actual current draw in amperes. Most car batteries don't even have an amp hour rating because they're not made for that. They use cold cranking amps. It will work, but it ain't a best in class solution.
There.  I said it.

OMMOHY
Contrarian in Residence  
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#7
RE: Dreamstation powered off of a car battery?
I had a lot of misconceptions on the Car Battery & CPAP... so i'm going to look in another direction.... I've seen a number of batteries on Amazon that appear to work well with CPAP. that may be a safer way to go.... (I did a search in Amazon for "cpap battery for camping") That makes more sense to me, and given the cost of some of the DIY approaches appears to be a wash.

thank you all for your comments, it's what I needed to hear.

Jim
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