How do the battery testers on battery packages work?
How do the battery testers on battery packages work? The little disposable battery testers that you see on batteries or battery packages are a great example of combined technologies — several existing technologies have been combined in a completely new way! Battery testers depend on two special types of ink: thermochromic and conductive inks. Thermochromic ink changes color depending on its temperature. Conductive ink can conduct electricity. By applying layers of these special inks along with a layer of normal ink using a fairly normal printing press, it is possible to create an extremely inexpensive printed design that changes depending on the amount of electricity it receives. There are two types of thermochromic ink: liquid crystal and leucodye. Liquid crystal based thermochromic ink is sensitive to very small changes in temperature, but it is fairly difficult to manufacture. This makes it perfect for use in items like thermometers
