I have the g3 and have been using it for the past 3 years. When I use it on 2l it last for 4 hours. Now I’m on 3l and it last for 2 1/2-3 hours. I would get extra batteries if I was you. I brought an extra battery off Amazon for $199. They are almost $400 on Inogen website. I have been using it for over a month now with no problems. It is the exact same battery/model number as the one I got with my machine. I haven’t traveled on an airplane since my diagnosis so I’m not sure how they would work but with the way you have delays now days I wouldn’t risk traveling with just one battery. Good luck and enjoy your trip!