12 Volt Power to My Outlets
So I am wanting to start boondocking some. I plan to start out slow with short excursions, 2-3 days. My problem is that my wife uses a cpap at night. It runs on 12 volts because the output of the powe...
Forum Discussion
The figures that MEX gives probably vary by machine as well as manufacturer.
A few observations from my experience using CPAP in an RV.
In my own experience, my Respironics machine (REMStar Auto) worked very well on 12 VDC. I boondock a lot in cold weather (spring and fall). I do not know for sure whether my voltage at the machine ever fell below 11.5, but it likely did so. I can’t remember ever disconnecting my CPAP from 12 VDC when charging the batteries using a generator plus the on-board converter (WFCO). I’m sure voltage went above 13.5 when charging, but then I was never using the CPAP at the time. I’ve never had a problem. At 19,000 plus hours it is still going strong.
The new rig has a modified sine-wave inverter and I’ve only used the old CPAP about 10 nights with it, so far. It remains to be seen whether that becomes a problem.
My wife used a ResMed VPAP Adapt ASV in the past and it was no end of problems. First of all, the 12 VDC cord cost over $100, vs. $25 for the Respironics. When we went to use it in the TT, it immediately shut down. The only way to get it started again was to start up the Yamaha Ef1000is and plug it into 120 VAC. Then it would immediately fail again when returned to 12 VDC. Long story short, after speaking to a technician/engineer with ResMed, I found that it was designed to shut down if the voltage went below 12.00 VDC. Camping in the mountains in the early spring with batteries in a box on the tongue, good luck maintaining 12.00 VDC or better, especially if something else using 12 volts (such as the furnace blower) cycles on. The technician/engineer protested that they worked fine for him, in the lab with his 12-volt power supply, and argued that there was something inherently wrong with using 2 T-105s in series and that it was my fault because of that! As I told the technician/engineer, 1) I was using a big 12-volt battery that I could carry around in 2 6-volt packages and 2) their product was designed to fail in the real world, where batteries sometimes get cold and their machine isn’t always the only thing drawing power!
The answer was a small pure sine-wave inverter. I installed a small Samlex (300/400? Watt) pure sine inverter just inside the front wall, using heavy wire (AWG 8) for the short run, and had no further problems. (I wish I had thought to keep that little Samlex when I sold the TT.)
I bought the Samlex after trying another brand of pure sine inverter recommended by a CPAP place failed miserably – sorry, I can’t recall the other brand. (It released the smoke inside when after installing I load tested it using a portable lamp with a 100 Watt bulb!) The Samlex is worth a few extra bucks.
Wayne
A few observations from my experience using CPAP in an RV.
In my own experience, my Respironics machine (REMStar Auto) worked very well on 12 VDC. I boondock a lot in cold weather (spring and fall). I do not know for sure whether my voltage at the machine ever fell below 11.5, but it likely did so. I can’t remember ever disconnecting my CPAP from 12 VDC when charging the batteries using a generator plus the on-board converter (WFCO). I’m sure voltage went above 13.5 when charging, but then I was never using the CPAP at the time. I’ve never had a problem. At 19,000 plus hours it is still going strong.
The new rig has a modified sine-wave inverter and I’ve only used the old CPAP about 10 nights with it, so far. It remains to be seen whether that becomes a problem.
My wife used a ResMed VPAP Adapt ASV in the past and it was no end of problems. First of all, the 12 VDC cord cost over $100, vs. $25 for the Respironics. When we went to use it in the TT, it immediately shut down. The only way to get it started again was to start up the Yamaha Ef1000is and plug it into 120 VAC. Then it would immediately fail again when returned to 12 VDC. Long story short, after speaking to a technician/engineer with ResMed, I found that it was designed to shut down if the voltage went below 12.00 VDC. Camping in the mountains in the early spring with batteries in a box on the tongue, good luck maintaining 12.00 VDC or better, especially if something else using 12 volts (such as the furnace blower) cycles on. The technician/engineer protested that they worked fine for him, in the lab with his 12-volt power supply, and argued that there was something inherently wrong with using 2 T-105s in series and that it was my fault because of that! As I told the technician/engineer, 1) I was using a big 12-volt battery that I could carry around in 2 6-volt packages and 2) their product was designed to fail in the real world, where batteries sometimes get cold and their machine isn’t always the only thing drawing power!
The answer was a small pure sine-wave inverter. I installed a small Samlex (300/400? Watt) pure sine inverter just inside the front wall, using heavy wire (AWG 8) for the short run, and had no further problems. (I wish I had thought to keep that little Samlex when I sold the TT.)
I bought the Samlex after trying another brand of pure sine inverter recommended by a CPAP place failed miserably – sorry, I can’t recall the other brand. (It released the smoke inside when after installing I load tested it using a portable lamp with a 100 Watt bulb!) The Samlex is worth a few extra bucks.
Wayne
