square ends for headphone batteries

thingiverse

Headphone battery problems got you stumped? Can't find replacements with square ends? If you try to swap in regular AAA NiMH batteries, they just won't turn on. What's going on here? It all comes down to tiny little switches at the negative end of each battery compartment that need to be depressed. Here's how to fix it: print out a replacement part, cut it in half with diagonal cutters, and trim both pieces to fit (22mm long). Then shove the half-square end all the way down to the bottom of the compartment and slide it back to engage the switch. Now you can use standard AAA NiMH batteries again. Other types might fit, but only put NiMH back in the charger - trust us on this one.