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At its core, a typical alkaline battery, when freshly charged, boasts a voltage of around 1.5 to 1.6 volts, gradually decreasing as the charge diminishes. Utilizing a multimeter, one could measure this decline, but the PowerCheck simplified this process. By merely pressing on two dots on the battery’s label, users could activate a built-in system connected to a tiny heater that interacted with thermochromic material, changing the color of a gauge based on battery charge levels.