Experience with O2 Concentrators?

[Sandersmr]

My mom is looking to get a portable O2 concentrator that is FAA compliant. She recently went on supplemental O2 during the day as well as at night. In the past she would just rent a portable when it came time to fly (because most cabins are only pressurized to 8-10,000 feet altitude so less O2 %). Anyway, from the little reading I've done, it sounds like the battery life is an issue as some of the airlines, Delta included, require 150% of travel time in batteries.

So does anyone have any experience and/or recommendations?

[snowball]

I don't have any recommendations but do remember hearing of on system that somehow (and it's been awhile sense I read it the ad for it) took it from the air so you didn't have to rely on batteries as much haven't a clue as to how it worked what it's name was just remember thinking wow that sounds neat
good luck in your search
sheila