If you have a space problem in your carry on,remember that underwear has 2 sides so that will save you some space?
There's no reason why you can't put batteries in a jacket pocket securely, isolate terminals or put in ziplock or lipo bags.
I wear a jacket if I need to keep cabin bag weight down to the ridiculous 7kg limit here with Australian airlines, stuffing my pockets with books, magazines, water bottle, etc to make it, lol.
Did the TSA react to the Lipo bags.
Lipo bags are not usually required by any airline, but I feel they are a decent idea as they will contain a lipo runaway fire better than not having them.
But if they were substantially useful, I'm sure airlines would have made them mandatory for batteries such as ours.
Phones, laptops, etc, no special requirements, overall too hard to try and make such things compulsory for the masses of lithium batteries taken on board.
I wonder though, if lipo bags might actually make the cabin crews life harder in the event of a runaway lipo fire ?
The first thing they must do when a lipo starts runaway (heat and smoke) is cool it with water / soda water, etc !
My lipo bags (not used for batteries) at home are zippered up, with a flap over the zip all round, would be really hard to get big volumes of water onto them to cool them, if batteries are starting to smoke.
Once a lipo gets hot enough and virtually acts like a magnesium fire, a suitable fire extinguisher is also hampered if the batteries are contained in a lipo bag.
Maybe it best not to use them apart form storage at home for some sort of containment ?