CPAP usage

Johno02 wrote:
Stefonius, If you are using 12V, why do you need the power brick?? Unless you CPAP uses other than 12V input?? All my poser brick does is to change 120v to 12v. I am aware that some machines require other than 12v. And some folks use an converter to change 12v to 12v, then plug in a brick to change it back. My 12v outlet is on the bus from my Mh inverter, therefore doesn't care whether the power is from the battery or the inverter. With my two 12 coach batteries, Mine will run at least two nights, but I don't use the humidifer in the MH.

My unit, a ResMed S9 Autoset Elite, runs (internally) on 24V. The brick that came with it converts 120VAC to 24VDC. The optional brick I bought for boondocking (or long car trips) is a DC-to-DC converter, 12VDC to 24VDC.

BTW, even though I do not need the brick in the MH, I always carry it with us. We did have to stay at a hotel one night, and realized that I had forgotten it. Lucky, I did have my backup machine and a 120v cord for it.

Stefonius, If you are using 12V, why do you need the power brick?? Unless you CPAP uses other than 12V input?? All my poser brick does is to change 120v to 12v. I am aware that some machines require other than 12v. And some folks use an converter to change 12v to 12v, then plug in a brick to change it back. My 12v outlet is on the bus from my Mh inverter, therefore doesn't care whether the power is from the battery or the inverter. With my two 12 coach batteries, Mine will run at least two nights, but I don't use the humidifer in the MH.

Be aware that some brands/models of CPAP units are designed to operate only on 120 volts AC or on a proper capacity inverter from 12 volt DC. Some CPAP units will work on 12 volts dc via a cord with a proper connector that plugs directly into the CPAP unit (BUT) the connector must be wired to provide the proper polarity of 12volt dc power required by the CPAP unit. My older Res Med Auto Set CPAP requires the center contact to be wired as negative and outer contact as positive. If you have wrong polarity, CPAP unit may be damaged. There is little standardization of CPAP power requirements. I think that some CPAP makers want to sell you an expensive portable battery pack and charger. It is important to understand alternate power requirements for RV use as well as when you have a power outage, wherever you happen to be. PS: Important: If you must use your CPAP in a hospital, make special arrangements with your surgeon and hospital staff to use your personal CPAP in the hospital room after surgery. A respiratory technician may need to inspect and OK your CPAP unit for use for legal reasons. PS: if you don't need to use the heated humidifier attachment, you may not need 120volt AC power and may be able to run on 12 volt dc battery power.

When I got my BiPap machine they gave me a bunch of paperwork with it that included the same warning. They consider your CPap to be a life support device and as such figure the same rules apply as used by hospitals. They're just covering their backsides.

As for how to power the machine, in my last two rigs I just used a DC outlet by the bed powered by it's own group 24 battery. I used the separate battery because my old Machine would sometimes shut down when I got a semi low voltage situation occur when the furnace kicked in.

For my current rig, I simply have a 600 watt pure sine inverter I run all night that powers the whole 5er. Doesn't draw much power really and works good with my setup.

For my Bi-Pap Machine I installed a 12v plug by the bed. I also have a back-up battery by Respironics, I use a Respironics M-Series Auto Bi-Pap Machine. My coach has 6 additional house battery's and 3- 100w solar panels..

Likely the company is protecting itself from someone using a really long, very light gauge extension cord. At 120v, a 14 ga. cord would be more than sufficient - it's the same as most house wiring! To be extra secure, use a "heavy duty" (12 ga.).

Looking at voltage drop charts for 12v over a 25' run, at the amps that were noted, minimum wire size is 12 ga. I'd probably even want to be sure, and go up one wire size to 10 ga., but that would be a pretty heavy run of wire, which probably only would be suitable if you were hiding it and using it to create a new 12 v outlet near the bed.

Tiger4x4RV wrote:

My house batteries recharge from the truck engine; I have no solar, no generator, and rarely any shore power.

So I assume that means that you need to run the truck for several hours every 3 days or so FOR THE SOLE PURPOSE OF RECHARGING THE BATTERIES....right ?? That's a REALLY inefficient use of such a big engine, especially if it is just sitting there at idle speed.

I believe Drew's response is correct. Companies do all the can to protect their back side. They fear someone uses a damaged extension cord or perhaps uses a homemade poorly constructed cord.

I installed a 12v outlet next to the bed in our fifth wheel. It's wired directly to the house batteries (well, to the buss bar that they connect directly to, just upstream of the master disconnect switch), using an inline fuse and 10 gauge wire. I can now use my CPAP with the manufacturer-supplied 12v power brick, even when I'm boondocking for a week. It took a few hours one afternoon, and a few bucks in parts from Radio Shack.