CPAP and battery power

[Tequila]

My old RV had invertor output next to the bed, the new one does not and there is no handy spot to tap 12V. My idea is this. Buy a 120V relay with double throw 120v contacts. Remove the 12 volt feed from the back of the convertor that feeds the bed plugs. Buy a 1000 watt invertor and wire it through the relay such that when there is 120v shore power, the relay powers up and switches 12Ov to those plugs. When 120v is not present, the relay goes to its resting position and switches 120V output form the invertor to those plugs. The 2 bed plugs are on their own circuit

I have plenty of room behind the convertor box to accomodate the relay and the invertor.

Anyone see an issue with this?

[Tequila]

I also wonder why RV manufacrturers do not address this issue. On my current RV, I ordered from the manufacturer and had them split the power outlets so 1/2 was on shore, 1/2 from inverter output. Worked well, they should all do it.

[Tequila]

oughtsix wrote:
My CPAP is 120v only so I purchased a barely used Respironics RemStar off of Craigslist for $125. It uses a 12v brick power supply. I used a RadioShack 12v universal power supply with the interchangeable tips. Works perfect! Much better than doing a whole bunch of wiring and doesn't pull as much current of having an inverter in the mix.

Nope I need either 12v or 120v. No 12 v available in that area without butchering to get at the reading light fixture wiring. And when boondocking I do not have 120v. That is the issue. Also I spend all winter in Mexico and the power there, via my protector, is variable and clicks on and off all night long, so an auto switchover would be nice.

[mlts22]

I've seen a number of people use a "battery pack" like a Duracell 600. It is 165 bones from Amazon, but I've seen that is a lot cheaper than the CPAP batteries.

[Still_Searchin_]

I ran 8 gauge wires from the battery to a junction box under the bed, then 10 guage wire from the solar panel goes to that junction (thru a controller), and a 12 gauge wire goes to a 12 volt outlet by the bed for the cpap. I also plug in a 400 watt portable inverter into that 12 volt outlet when I want to run or charge my laptop, electric razor & cellphone. The smaller wires that feed the 12 volt outlet by the TV don't seem to provide enough juice to run the 400 watt inverter without chatter.
When boondocking, I don't use the humidifier on the cpap, and using it only on 12volt, it will only take my two 6 volt Trojan batteries down about 1/10 to 2/10 of a volt after a full nite of use + water pump use + LED lites on for 4 hrs. It would probably take another 2/10 of a volt drop if I used the humidifier, though I haven't tried that.

[Timothy]

Or you could just use a standard 3 way light switch and select your power source manually. Wire the outlet to the common terminal on the switch, normal power feed to one terminal and invertor feed to the other. Be careful to choose an inverter that will meet the power quality requirements of the cpap.

[oughtsix]

I used an Optima Yellow top battery for tent camping with my CPAP the past few years. I could easily go 4 nights and have plenty of juice left in the Optima. Last weekend was my first trip in our new trailer. I sleep much better with the trailer around me and a real bed under me. We were tethered so I just used the 120V to 12v brick. I will be using the Respronics on 12v when we are dry camping though.

[bluie5]

I used mine with an inverter plugged into the 12v jack an then an extension cord to my machine. With my new rig I'm going to get the 12v plug for it and tap into a light and put a 12v jack on my side of the bed. The fan on my inverter ran constantly so hopefully with using just the 12v now it will save some juice.

[jaycocreek]

12 volt here also.I have a seperate battery, size 27, I use for the cpap only.I do use an inverter for things, but not on the cpap

[oughtsix]

My CPAP is 120v only so I purchased a barely used Respironics RemStar off of Craigslist for $125. It uses a 12v brick power supply. I used a RadioShack 12v universal power supply with the interchangeable tips. Works perfect! Much better than doing a whole bunch of wiring and doesn't pull as much current of having an inverter in the mix.

[Nvr2loud]

I misread your post, so I deleted my answer...

I thought you NEEDED 12 volt power near your bed, but you actually need 120 volt power near your bed. Can you not just run an extension cord from one of the other 120 volt outlets in the trailer?

[Bumpyroad]

and if you use a pass over humidifier, rather than a heated one, your power needs will be minimal.
bumpy

[beemerphile1]

Sounds like an awful complicated solution to what may be a simple problem. Most CPAPs sold today operate on 12vdc or 24vdc. Both have an adapter/plug that allows operating from a 12vdc circuit.

If your CPAP is one of them, buy the 12vdc adapter and plug into the 12vdc system of your RV. What voltage does your CPAP really need? Look at the label on the back.

[Tiger4x4RV]

Are you sure you need the inverter? My CPAP runs on 12V, although I did have to buy a special !2V cable for it. I'm new to CPAP, but have read that most of them run on !2V; 12V is produced by the big block thing on the 120V cord that comes with the machine. By running straight from 12V, you are cutting out the inefficient middleman, the inverter.

[2oldman]

If 'resting position' is with the other contacts closed, that will work.

It would be easier and likely safer to just keep the inverter on battery 24/7. When shore is present it will be charging batteries.