Yeah, everything said here I'm going to agree with. No one's going to stop you from running these in your games, I suppose but I would never allow anyone to use them in any of my games. As is, starting off the game around 10 refresh or so, everything you can make is, for the most part, pretty balanced. There really isn't much in the lines of power gaming. Well, as the game progresses to higher refresh values from hitting major milestones, wizards slowly inch ahead. Sure, it takes a decent while but it's a class that can literally do ANYTHING. One of the few restriction on them is the stress of casting continually.
Past that, who cares about 17 shifts to create a battery? You can mitigate most/all of those shifts to receive no stress/consequences via good thaumaturgy. Past that, this would be like the creation of any other enchanted item type of thing where it would most likely not be taking place during game but over a period of time "off-screen." As such, any stress that would still be induced by the making of the item is nullified. Hence it simply not being balanced. Sure, they would need to take up an item slot - probably multiple for a single battery depending on the number of shifts - but it's still just an item slot for what would have been situationally excellent benefits, but is instead entirely generally excellent benefits.
To summarize: Entirely unbalanced. Stick to potions.