Interesting question. My guess is that are two different classes of objects, some with charges, like flashlight. Others add to your carrying capacity, like duffel bags.
And yet others can store other items inside, like scabbards.
That begs the question of how a merged class, that increases your carrying capacity, can add items to it, and has an electric charge would behave.
I mean, if I find a cooling box, will all my inventory be refigerated? What if its a very small box, and I transport 15 Pizzas through a summer? Will they spoil slower? Can they be frozen?