It’s an age-old problem: The batteries in the remote die. While you’re replacing them you get distracted for a second and can’t tell which batteries are dead and which work. Unless the batteries came with some sort of painful gimmick, it’s impossible to tell just from looking at them. Until this test emerged.
This month, scientists at Princeton University managed to prove that this test is in fact accurate. Using “non-destructive mechanical testing” (read: dropping), the scientists were able to show that the amount of charge a battery has left is inversely proportional to how bouncy the battery is.
As Scientific American notes, alkaline batteries contain a zinc gel that oxidizes as the battery discharges. The gel gets denser the more it oxidizes, causing it to bounce higher when it’s dropped, like a golf ball on freshly-paved asphalt.
As we all now know, it’s totally fine to throw out most regular batteries, but now you can easily double-check that you’re tossing out the right the ones.
The above image was taken by John Seb Barber and shared under a Creative Commons license on Flickr.