I am talking about batteries for airflight or even outdoor stuff like camping. I usually travel on flights that spans from the late evening to early morning. I am expected to sleep during the whole duration of the flight.
For me, business class seats always have a power outlet, and so I've not had to use a battery with my CPAP while flying.
For economy seats, I'd be sleeping almost upright, and my apnea is not an issue in that position. Also, I find the limited space in coach makes is really difficult to try to deploy a cpap - where will you put your unit? On the ground? I'm not sure if you're aware, but the carpet of the flight is one the *filthiest* location on any flight, and second only to the toilet floor; and I wouldn't want my cpap to be sending me air right off it. On the fold out table, or in your lap? Possible, but you might like to get a shorter hose if you're still using the 6ft hose your unit came with (I use a 4ft hose with my travel cpap); but I would be worried if it could get damaged if dropped also.
Instead, a good travel pillow is necessary for restful sleep in coach. The best travel pillow I've used, and still use even till today, is the
memory foam Komfort Kollar. I've had mine for almost 7 years now, and am still very pleased with it. The only downside is it's rather bulky, and takes up a fair bit of space; but I just strap it onto the outside of my carry-on.
I also always use eyeshades, earplugs, *and* a pair of over-ear noise canceling headphones to sleep.
Lately, I've heard about the
TRTL travel pillow, which I'm thinking of trying out. It seems to have pretty good reviews, and I'm always on the lookout for anything that might help increase my comfort while flying.
As for camping, it's a whole different ballgame. The first question would be, how many nights do you expect to be outfield with no access to a power outlet?
I bought a Transcend Auto, with multi-night battery P8, as my outfield trips are usually up to 2 nights, and only very occasionally up to 3. For my use, the multi-night battery is more than enough for 2, and has been enough to get me though the 3rd night (we usually only get 5-6h of sleep each night).
One reason why I decided not to get the HDM Z1 was because the unit drains the battery while it is plugged into the powershell, even while it is turned off. In addition, it appears to require a custom sized tube, and I'm not a huge fan of vendor lock-in.
If you would be outfield, a dedicated travel cpap may be recommended. They're designed for that purpose, and have a lower power draw, and so they can last longer with smaller batteries.
My transcend battery is 14.4V, 5200mAH (~ 74.88Wh), and it can power the unit for up to 16 hours at 14cm pressure. The Airsense 10 would appear to require a 12V, 18700mAH (~ 224.4Wh) battery for the same 16 hours at 14cm pressure (without the 50% safety margin; with, it comes up to 28000mah ~ 336Wh).
You can't fly though some airports (*) with a Li-ion battery rated more than 100Wh. You need a written letter from the airline if you wish to carry a battery more than 160Wh; but that includes all batteries in your carry on, so a laptop will take away from that as well. By default, you even won't be able to fly with 1 night (8h ~ 112.2Wh) of battery for your Airsense 10.
(*) I'm using PEK, because I transit though them semi-frequently and am familiar with their restrictions. Other airlines and airports may be more or less restrictive.