When traveling that deals with TSA or any other equivalent, I always keep my batteries, vape, cell, laptop, in easy reach. They will always have you place batteries in their own tray or bin when getting scanned. Hell, I had to remove my fitbit from my wrist before going through once. I do one of 2 things when I travel.
1. 99% of the time I am traveling with a laptop. Any airline I travel on allows a carry on and a laptop bag to be carried on. And due to available space, the carry on can be required to be checked in, but a laptop bag will always be allowed to be carried on (to my knowledge). So I will put my mods and batteries with battery cases into a pocket in my laptop bag.
2. My carry on is usually a backpack and on trips that I do not take my laptop. My backpack has clip and buckles and straps and junk like that. I have a small Samsonite bag that is a small messenger tote that can attach to my backpack and is small, about 6x8 inches. If my backpack needs to be checked due to space, which has never happened to me, then that little tote is tiny enough to fit with me on the plane and carries my vape gear, mods, batteries, tanks and some juice.