I was coming here to mention the inventory duping glitch I encountered, but I see you've already released an update that addresses that, sooo...
Instead maybe a suggestion for the stacking:
Can you make it so the used batteries don't stack? At the moment they stack with new batteries which makes is a little hard to figure out which to keep and which to throw away if you have multiple.
Other than that, I've loved the way you've been going with the game so far. I'm super excited to see what you come up with next!