Battery power for CPAP?

[johnnyrocks]

I am planning a camping trip and would like to use my ResMed Elite EPR CPAP. Can I simply use a 12V marine battery with a voltage inverter? If so, how much time can I expect from the battery? Do I need any other accessories? Thank you

[Doc J]

Do a search on this subject, there have been many good threads about this. I'm an electronics tech and some of the battery info was deeper than I had ever heard. I just got a new deep cycle marine battery (mostly for a trolling motor) to use. Now I have to decide if I should get the 12 volt to 24 volt convertor for my Res Med s9 or use a 12 volt to 120 volt ac inverter. I'm sure the dc to dc would be much more efficient, but I already have the ac inverter. Good luck.
here is the Res Med battery info link someone else used, http://www.resmed.com/assets/documents/s...lo_eng.pdf

[justMongo]

Do a search on this subject, there have been many good threads about this. I'm an electronics tech and some of the battery info was deeper than I had ever heard. I just got a new deep cycle marine battery (mostly for a trolling motor) to use. Now I have to decide if I should get the 12 volt to 24 volt convertor for my Res Med s9 or use a 12 volt to 120 volt ac inverter. I'm sure the dc to dc would be much more efficient, but I already have the ac inverter. Good luck.
here is the Res Med battery info link someone else used, http://www.resmed.com/assets/documents/s...lo_eng.pdf

Yes. With an upconverter followed by the switching power supply brick you waste energy. The 12 to 24 converter is more efficient than a double conversion solution.

One can estimate run time on a deep cycle battery by looking at the bottom plate on the xPAP machine. Say it says, 24V at 2 Ampere. That's 48 Watts. At 100% conversion efficiency, you'd pull 4 Amperes from a 12V battery. If the battery capacity is 70 Amp-Hr, then at most your run time is 70 AH/4A = 17.5 Hours. Factoring in conversion loss and a desire to not totally drain the battery, maybe you get 12 hours.

[trish6hundred]

Hi johnnyrocks,
WELCOME! to the forum.!
There are some very detailed threads here on the board about battery power, lots of good information.
Best of luck to you.

[mjbearit]

I read something not long ago about AC inverters need to be Sine A/C inverters. Now I haven't messed with this level of electrical knowledge for ... longer than I care to admit, so I'm not exactly sure what that means or how true it is, but, if you are going to create your own rather than get something already created, you might want to investigate this.

Mike

[dwd1249]

I use a 300w pure sine wave inverter with a 45ah deep cycle battery and so far have had no problems running it for 3 nights. I have run the cpap on a modified sine wave inverter but felt that with the electronics in it a pure sine wave would be better.
I got a cheap 600w pure sine wave inverter off Ebay that wouldn't run it. Might have just been a faulty one. I blew it up when I was checking it out on different loads to see what was up with it. Didn't brother sending it back as I had it for a few months.
The 300w Projector inverter I got does the job.

HTH

[Doc J]

It's in that Res med Link that the older models need pure sign wave inverter and the S9 will work with a modified sign wave. Both are referring to using the humidifier. I too think that is hard on electronics and have ordered the 12volt to 24volt DC converter for my S9 and will go camping to my favorite non powered site as soon as the dang cold snap (check local listings) gets over.

[justMongo]

If you buy the ResMed inverter or 12V to 24 V converter intended for use on the ResMed machine, it will work subject to any limitations noted by ResMad.

The point about a pure sine converters actually came up when looking into the use of line voltage backup units originally intended for computers.
Many of them use a step approximation to a sine wave. Those looking for computer type backup supplies can now get reasonably priced pure sine output units as computers with internal power supplies that have power factor correction (angle between current and voltage phase) require a pure sine wave. However these units will not run an xPAP machine all night; they are for short term outages.

[Doc J]

So mongo what's it like to drive a Train?....... Sorry I had to ask, I used to play in a band with a good old southern gentleman and I was asking him about a guy "was he an engineer or what"? and he came back "I don't know if he ever drove no train or not" and now that's what my brain thinks when I hear engineer. So I had to put that out there, thanks for the advice on the battery issues.
Doc J

[justMongo]

So mongo what's it like to drive a Train?....... Sorry I had to ask, I used to play in a band with a good old southern gentleman and I was asking him about a guy "was he an engineer or what"? and he came back "I don't know if he ever drove no train or not" and now that's what my brain thinks when I hear engineer. So I had to put that out there, thanks for the advice on the battery issues.
Doc J

Well, Doc J, I've used that joke myself. And I take it with a smile!
My specialty was satellites; and power management is crucial.