About ten years ago, Duracell began to market its Copper Top^TM cells with a built-in battery tester. Initially the testers were built into the paper/bubble packaging; later they were placed directly onto the covers of some cells. Although this practice seems to have been abandoned for the most part, it is still possible to find on-card testers being sold, as shown on the image at the right.

The magnified image below shows the two sides of one of the original testers. Explain how the Copper Top^TM Tester for the 9 V battery works by using simple circuit concepts, properties of resistors, and determining how the display works.