this is Randy in Idaho.  we got our first rv about a month ago. a 1977 monaco, class c on a dodge chasiss.  does anyone have experance using a cpap? and know how much electricity it uses.  the last time i went tent camping and used the car battery, it went flat after 3 days, even though i ran the car for an hour every day, it was a new battery and a deep cycle.


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Wait, you're using a deep cycle to start your rig?

Deep cycle batteries are designed to let go of its stored charge as slow as possible, to last longer than starting batteries. That means they also have the characteristics of not charging too fast. Slow in, Slow out.

Cranking batteries are designed to deliver a punch to the starter to crank it full bore in the coldest conditions.They also charge in less than 30 minutes.

A deep cycle is also not built to deliver high amps in a hurry. I'm willing to bet your deep cycle battery was not that low, just that it couldn't deliver the punch need to start your rig.

Your rig has to have a deep cycle stuffed under a counter somewhere. Or at least a mounting spot where one used to be. They are usually on the floor level in case of overflow. Mine is in the opposite corner of the rig than the Genny. They could be anywhere. Your rig will run off the under hood battery as they are hooked together through a battery switch. There are several types of switching devices. You can buy a manual switch with "Batt 1; Batt 2 & Both" selections. There are electronic ones that charge both batteries while driving and when the engine shuts off, a transistor directs all the drain to only the deep cycle to keep your cranking battery fresh. Sometimes owners AND mechanics that don't understand the systems actually disconnect them and run off one battery out of ignorance.

I have seen these "Start/Deep cycle" combo batteries for boats with trolling motors, but don't trust them in your rig, I don't care what the salesman says. Get 2 batteries and make sure the separation switching works.

There are youtubes all over the place with instructional vids. When you are searching for info, don't forget to fire up youtube and utilize its search engine too.

I like the other folks suggesting solar and small efficient generators for medical equipment safety.

You can baffle any Gen Set with foam. I worked for a studio equipment repair shop and we fabricated almost soundproof units. You couldn't hear a 350 Cummins under full load standing 40 feet from the Gen Set. It's all how you baffle the box. You use a folded horn kinda design. The cooling air goes out the bottom and the exhaust goes high in the air. Like a car, the more bends you have in your exhaust pipe, the better. I ran a length of pipe across my frame and back with five 90 degree bends in it. Then the pipe goes into a fork lift muffler and up a straight pipe to 2 feet above roof line. You have to be standing on the roof to hear any exhaust noise. I havent seen a Gen Box on an RV that didn't have the room to do it right.

I've had people walk right by my Onan 4.3 and not realize that it's running. Occasionally someone will stop and look at the Gen door and turn their head like a puppy trying to hear where that soft hum is coming from. But they are standing in my space when they hear it. Needless to say, I run my gen a tad outside the hours of "Campground Genny Etiquette".

This ought to get you started...



I'm recommending the Duracell Powerpack 600. (Also badged as a Xantrex 600, but more expensive that way.)  It's a nice little package, will run your cpap all night long.  Here's the Amazon link a href="http://tinyurl.com/7y667j4>" target="_blank">http://tinyurl.com/7y667j4>;.

In my little travel trailer I have a pair of 12V AGM batteries, but I still carry the Duracell 600 in case I need to jump start my truck) I have taken my CPAP around the world twice and to Asia every year for the past 10 or 12 years.  It'll run on 220v 50hz as well as 120v 60hz.  I wouldn't dream of sleeping without it.

I am reconsidering my reply to this question -- it was hasty and ill-advised.  I cannot delete, apparently, or I would.  The ResMed S8 which I use in my camper is not recommended for use on a modified sinewave inverter (which is what I have for my battery bank).  I've never had any problems, and I have never damaged the machine, but it's not recommended as I have read.

Of course ResMed makes a battery for their unit, but it's not for unlimited use -- suckers gotta be charged. What's more, ResMed recommends that I use their converter (12vdc voltage regulator, basically) $74 from CPAP.com to run the S8 off of 12vdc power.  OK, no problem.  I'll get one.

I appreciate your response Michael Katz.  Maybe since CPAP is not life sustaining (versus a vent) , a battery would be adequate.  I am looking at it from a medical point of view and may be being uber careful!  I also will look into the powerpack 600 to use for my o2, although I think it draws a LOT more power. (based on the marked increase in electric bill when I started using the o2.  )

ALWAYS open to learning something new!  Thanks for info.

Thanks, Barbara.  I should have qualified my remarks to merely CPAP.  And of course you're right that if my CPAP failed in the night, I'd be miserable but likely not life-threatened.  Honda used to make a tiny 650w inverter/generator but now their smallest is 1000 watts.  Still, I'd organize a bank of batteries that would get you through the night, and recharge them in the morning (or afternoon!) with a small putt putt.


don't think it will work for my concentrator.......it says 290 watts!!!




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