12 volt plugs

Thanks Roy, but the battery bank is actually about 20 feet from the bed...the batteries are under the steps going inside and the bed is at the rear of the motorhome. It's a 32' long motorhome. I ordered a 12 volt converter plug for the CPAP machine and am going to try something at home. If it doesn't work, then we are gonna just go ahead and spend the $250 and get the dedicated lithium battery built for them that can be recharged in a few hours.

Brian - Blue Sea sells one of these 2 pole three throw cam rotary 120VAC switches.. You can get this with many added poles to switch the load source 120VAC to either shore power or generator/power inverter etc as required. This would be done at the 120VAC Power Distribution Panel where your circuit breakers are at...



BLUE SEA CAM SWITCHES

The BLUE SEA model is probably very expensive ($300)... C3CONTROLS sells a similar 120vAC 30 AMP rotary cam switch (NEWARK CATALONG) for around $80 I think I read some years back...



This shown is using multiple poles which results in alot of wiring. If yours had only one pole it would be much less wiring involved...

I went the cheap way and added a couple of multi-head extension cord drops with ON-OFF cwitches in my OFF-ROAD trailer from my 600WATT PURE SINE WAVE Power Inverter. I just routed the extension cords behind the cabinets and they came up on the back side of a table top with one location near my HDTV setup and the other one near our main bed location. The extension cord drops are completey out of sight... My 600WATT AIMs Power Inverter (AMAZON) is always on so this gives me a good 120VAC power source where ever we are located at...



You can see my always-on extension cord drop locations in this floor plan drawing


I drew this up for a guy wanting to the same thing is his travel trailer... Might give some thoughts..


The second path would go to your bed location which is probably near your battery bank for the CPAP...

Roy Ken

wbwood wrote:
What I am wanting to do is figure out a way to power a cpap when not on electricity. The battery bank is in the front part of the Motorhome and the bed is in the back. There are no 12 volt plugs anywhere else in the coach. I though it getting a pure sine wave inverter and installing it, but the. I would have to run an extensions n cord through the Motorhome because of trying to mount the inverter near the batteries. And then Finding a good pace to mount it is another thing.

Do you have space behind the breaker-fuse panel?

300w inverter could use the main feed from the 12v battery and a small transfer switch will connect power to the 120vac single branch circuit.

No pulling wire, just make connections.

There are a couple of ways to tell but the reply above is the best.

If you have two voltage indicators you can plug into both and fire up main engine, if you have a BIRD isolator system then you note.. Does the indicated voltage change when cranking (Yes = Chassis battery) does it increase soon as the engine fires (yes indicates chassis battery) or does it hold steady when cranking and go up 30 seconds AFTER engine fires = house battery.


On my RV, which has absolutly noting to do with yours.. Dash outlet is Chassis, all other outlets are house.

Disconnect a battery and see if they still have power. Yes, they are on the other battery. No, they are on that battery.

DrewE wrote:

For a load the size of the CPAP machine,

I am putting off getting into this as long as I can but have a friend who travels with his machine and I'm pretty sure that he said he ended up shopping around to find a CPAP with lower current draw so his batteries would power it overnight without going completely dead.

wbwood wrote:
The fuse panel, converter and all are under the bed. Putting a plug in that area would be ideal.

If you have an empty "extra" slot on your 12V fuse panel, just run a wire from there, put a fuse in, and put in a lighter socket at a convenient location. Running the wire should be pretty easy. You may have to remove the mattress and unscrew the deck of the bed or something along those lines to get access to the space.

If you don't have a spare 12V fuse location, it would require a tiny bit more fiddling and/or thinking, either tapping into an existing circuit that would not be used at the same time as the CPAP machine (or at least would not have a significant current draw) or possibly putting in an auxiliary 12V fuse panel.

For a load the size of the CPAP machine, there's no great advantage to running wires directly to the battery rather than the 12V distribution center assuming the DC wiring is at all reasonably set up.

Going from battery would be he easiest, but we are talking about 20' or so from the batteries to the bed.

The fuse panel, converter and all are under the bed. Putting a plug in that area would be ideal.

I'd suggest to pull two wires directly from the batteries or distribution panel to the new receptacle location. Fuse the positive phase wire.