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For a Science Fair project...

I'm looking for a 12V mechanical ticker that will count up while attached to a power source. The unit I bought only ticks up once when power is first introduced.

The experiment is to test what brand of battery runs the longest, and in differing environments. Ideally, start it up, check it periodically, and when the battery is spent, the counter will tell you how long the power lasted.

One of the easiest solution is with an Arduino: it supplies you with an ADC (Analog to Digital Conversion) allowing you to start a timer when you insert the power source, and an event can be triggered when the voltage drops to a predefined voltage. The timer will give you the time it took. Just one caveat, you have to reduce the voltage seen by the ADC pin of the Arduino (or Raspberry, an ESP32, or another MCU; the Raspberry is more a micro computer than an MCU; programming is required, but it allows you to "modify" the functionalities without modifying the hardware.)

That sounds like a fun project! For what you’re trying to do, you’ll need a continuous mechanical or electronic counter—something that advances as long as power is flowing, not just on startup. The one you bought is the “pulse” type, so it only ticks when voltage changes. Look for a DC hour meter or a motor-driven counter instead; those run continuously while powered and will give you a clear reading when the battery dies. They’re pretty cheap and easy to hook up, and should work perfectly for comparing battery life across your tests. Good luck with the experiment! google baseball