Steven Levy got a rare look inside Apple’s Input Design Lab:
The input device, dubbed the Magic Mouse 2, would look to users exactly like the previous model. But on the inside and underneath, everything would be different, mainly because Apple was switching to a rechargeable lithium battery instead of the previous replaceable alkaline ones.
Late in the process, everything seemed to be going fine. The internal lithium battery was custom-engineered to fit the cavity. The redesigned antenna — necessary to deal with the potential interference from an internal battery — was working well.
But one thing was totally unacceptable.
The mouse didn’t sound right.