I have some partial experience with my wife's S9 and my A10 machine running off battery power. However, it is with our 5th wheel trailer when running with no AC supply. We each have a ResMed 12 volt to 24 volt converter which we use in place of the normal 110 volt adapter. ResMed publishes a battery guide which gives the 12 volt current draw for an inverter solution (which we do not use) vs a voltage converter solution (which we use). The DC to DC converter is about 40% more efficient. From our trailer experience I would say that the ResMed guide is pretty accurate. We both draw about 1 amp at 12 volts. If you are using a battery solution and the DC to DC converter or equivalent you probably need a 10 amp hour 12 volt battery as a minimum. A motorcycle dry AGM would technically do it and would be reasonably cost effective, BUT I highly doubt you would get one on a flight unless it says it is a CPAP battery. And they are expensive. I believe the ResMed battery and adapter package is in the $700 range. Here is a link to the battery guide. The amp draw is quite dependent on the average pressure you use. A BiPAP generally operates at a higher pressure and the minimum draw may be over 1 amp, but you should be able to look it up. This low current draw is with the humidifier and heated hose turned off. That is one thing you should do before your flight as no matter which way you go, you may be limited on the plane for watts - figure out how to shut the humidifier off and the heated hose off. That is what we do when we operate on 12 volts from the trailer. We try to limit the current draw to the minimum because we depend on a solar panel to charge up the batteries each day.
As for the British Airways 747 on board I thought I found an easy answer for you, with a power guide pdf. The problem is that I found two of them and they are not the same. The power options you get depend on the class of ticket you buy. If you are flying first class no problem with just using your standard AC adapter. If flying economy you may be out of luck and need a battery solution. In between those two extremes it is a bit of a mystery. In any case Here are some links I found. Probably what you should do is contact British Airways and find out exactly what power you are going to get at your seat.
Traveling with a Medical Condition - See Section on CPAP Machine
In Seat Power: Quick Guide - Version 1
In Seat Power: Quick Guide - Version 2
I don't see any easy way of using that 15 volt outlet that seems to be all that is available in some cases depending on the class of ticket.
Hope that helps some. I think your only problem is the flight over, as your existing dual voltage adapter and plug adapter should do just fine in Europe.
Appreciate the insights, all the more so because we just got a travel trailer and have been spending a lot of time up in the mountains of Arizona to escape the heat. We're in an RV Park with power, but I wondered what route to take for my BIPAP AirSense 10 when we cut the cord and go boondocking.
The battery devices I'm looking at are all 95-100 Watt-hours, which is effectively what the official Resmed battery solution provides... But as you say, those are $800-ish. I've found several similarly powered units in the $200-$350 range. I'm thinking of ordering a POWERMOD BPCPAP24V-KT unit from Amazon ($250) or Magnadyne,the manufacturer ($200). Amazon's return policies make them attractive, but fifty bucks is, well, fifty bucks.
My BIPAP is needed for the severity of my condition - I run at 17 on inhale and 13 on exhale, which requires more than typical power consumption. I have a Kill-a-Watt meter so I can see how much power it takes per hour on average... But the wild card is how much the battery unit will REALLY provide. Normally it is not what they are rated in the sales and marketing literature and specs - I'm afraid I will need to buy one and try it out.
To your point, they are definitely labeled as remote CPAP power supplies and should be allowed on the plane. I will be calling BA to get verbal approval and details on the outlets, but most airlines allow lithium ion batteries up to 100 watt-hours max, which is why they are all in that same capacity range.
But I'm thinking that I want something like this anyway for either tent or trailer camping without power. A generator would charge this during the day, solar and vehicle outlets are also options.
Amp hours is a term which assumes the battery is 12 volts. 10 amp hours in a 12 volt is 120 watt hours. I would consider that the very minimum to survive a night at 15 cm average range without using the heated hose and humidifier. That Magnadyne unit in 24 volts looks like it should do it, but you were looking for actual experience (which counts), I don't have that.
For trailer off grid camping I think I would go the route of 12 to 24 volt conversion with the ResMed converter which is in the $100 range. That assumes you have a reasonable size battery in your unit. We use two 6 volt golf cart batteries in series plus a 70 watt solar panel to recharge. At about 150 lbs I doubt they will let you on a plane with that setup though! And if I was buying again, I would get a 100 watt solar panel, which seems to be the current Costco in store standard. Based on actual experience I think we could camp indefinitely with that setup while using two ResMed CPAPs.
One additional point. Whatever you choose, make sure it is well tested before your trip. I told my wife that she did not need to bring her normal AC adapter on a trip we made earlier this summer. We could always run off the 12 volt power from the trailer whether or not we were plugged in to AC. Well her brand new ResMed DC to DC converter lasted 4 nights and then quit. There was a bad connection in the power cord. Fortunately she ignored my advice and brought the AC adapter and was fine for the time we had AC!
I can't get all technical (and am addressing just the travel trailer part of your ?) but I travel in a VW Eurovan with a second 12 volt, marine battery and inverter. Along with a small solar panel, this powers a fridge, lights, device chargers and CPAP with no problem. Overnight, there is barely a drain on the battery storage. When I looked into CPAP batteries for camping, they need to be recharged after 8 hours anyway.
My wife has been using a CPAP for almost 4 years now. We started out by using the RV batteries, an inverter, and one 70 watt solar panel. The trailer uses very little power as the lights are all LED, and we use propane for the fridge, cooking, and even outdoor lighting. What I found was that we were just keeping up to the CPAP drain with the one 70 watt solar panel. Then this year I got into the CPAP use as well. In theory we could have run both machines off the one inverter, but I was worried we would need another solar panel to do the recaharging. We also found is that it is hard to find an inverter that does not use a fan to keep cool, and that fan is much noisier than a CPAP. That is when I did some math and found we could run both CPAPs with the DC to DC converters (which have no cooling fans) for almost the same power as running one off an inverter. My plan was to try it this year and if it didn't work then buy another solar panel. It turned out to be not necessary as the one panel seems to manage. Using the furnace on 12 volts is a non starter though. It uses way too much power to recover the next day.
And you are correct that a CPAP battery/power supply solution is not really going to be ideal for camping, unless you only do one night stands without AC power. Although if a solar panel and inverter was used to recharge the CPAP battery during the day it might work if the solar panel was large enough.
All good points, thanks. My trailer has two deep cycle 12V batteries in parallel (12V systems throughout), and all of the lights are LEDs, so without air conditioning and running the fridge off propane, I might very well be able to just use a couple of solar panels to keep the batteries charged for lighting and BIPAP at night.
Also, thanks for the suggestion about the DC-DC converter and info on the higher efficiency that setup provides.
As a camper myself (Have a Keystone Cougar 5ver), I bought a generator for dry camping; not keen about the solar panel life and like my A/C, etc. I have a 3500 running watt Champion generator that I also use at the house when we have one of very frequent power outage. It has a push button start and if positioned away from a bedroom (either RV or home), isn't too annoying. We live rural as you might have guessed. Champion makes a dual fuel (propane / gasoline) generator that I really like and it is ultra dependable. Only thing that could be improved is some sort of gas gauge because filling (re-filling mostly) in the dark makes it easy to slop gas all over. I have never used the generator on propane. I bought a slightly used Generac home transfer switch on craigslist and had an electrician install it. I can power up the kitchen minus electric stove and microwave, the bedroom where we have a window A/C (we cut off main A/C at night to save a couple bucks), living room, bath, office; in fact most of the house other than A/C, well pump (240V), microwave, water heater and electric stove. Anyway, when power goes out, I start the generator, plug into a supplied outside wall outlet and flip the switches on the Generac from LINE to GENERATOR and we have power. Our power can go out for a few days at a time so I keep a few 5 gallon gas cans on hand. Life goes on in the event of a power outage. I can haul the generator with us on camping trips, if needed and it is RV ready; just plug in my 30A RV power cord and I am ready to brave the wild; Bipap works fine btw as does A/C; Just can't do A/C and microwave, etc, at the same time. I put the fridge on propane and the water heater on propane only. It works. And no solar panels with inverters and being without A/C (live in Texas!).