The portable concentrators battery life depends on what setting you are using it on. They all tell you 12 hours on setting 1, but you actually get 4 hours on setting 4, which is what I use for walking.
What I do when I get some place to visit is turn it down to setting 2 which is adequate for sitting visiting with someone or reading etc. I just have to remember to turn it back up to go to the bathroom or the car.
The worst thing is using a portable in public restrooms! I was never a fan anyway and using them is just really awkward.
Also remember the settings on an Inogen are not liters, the pulse dose doesn't provide liters. They are just numbers and you might use a different setting that with a constant flow concentrator.

I have a mini g4 inogen it's 2.3 pounds. But it is only pulse at 1, 2 or 3 ltrs.

Hi Kellie. I also use the green tanks when I am out and about. But I don't drive. (and my profile picture lies! 🤣🏁)

As a front seat passenger, I put the larger E-tank in the REAR and drape the hose over headrest. That way, IT would be hard for it to become a projectile in case of an accident. It's a real "dance" to get in the car during bad weather just the same. 🕺

The smaller M-size tanks work well in a canvas tote bag and you could probably tuck it under your knees - even as a driver. BUT of course, you won't be able to go as far or stay as long as you desire.

You will need a lot of this 💪💪for carrying your tank up a flight if stairs. I can't go anywhere that has three stories anymore.
IT is a trade off, indeed.

be Well