Science fair tech help.

[netherbawss235]

I am planning to do a Science Fair project using 3 types of batteries. Duracell Quantum, Duracell Coppertop, and Energizer Rechargeable Batteries. I want to stick them in flashlights and see how long they last. But instead of checking every hour or so I want to see if there is a solarpowered stopwatch kind of device that stops ticking when theres no more light. Is there a device that does that, and would that device reset when it runs out of energy?

[joshmcd]

Arduino!