Kona II: Brume

Doing this on the easiest difficulty will result in spawning more of these batteries. I had 38 and used 2 and the achievement unlocked, so you don’t need to save your batteries.

FYI... you have to be holding 40 at once, not collect 40 total. I realized when I was getting close that I'd definitely collected enough, but I'd used a few along the way.

Playing on the easy difficulty for a first playthrough, there are a LOT of batteries, so you don't have to really ration them at all. I'm sure the harder difficulties change this, but I was able to naturally pop this when I searched the old house after repairing it and going upstairs. There's a lot of game after that, too.