Building replacement proprietary battery packs
After getting into drone racing (where you need to take good manual care of your batteries because they're basically a bunch of cells soldered together), I realized that every battery we have everywhere is just some standard cells in some standard configuration.<p>With that knowledge, you can replace the battery in any gadget (small ones are usually 3.7V, or 1S), if you know how to care for it. Replacing the battery in a MiniDisk like this, I would maybe not trust the internal MiniDisk charger and charge by hand, but it should otherwise work identically to the factory battery.