Lit The Materials You Would Use To Make A Battery Tester.?

Answer 1

A really simple battery tester is a flashlight bulb. The strenght of light produced is proportional to the strenght of the battery. Just use a bulb with the appropriate voltage rating.

Answer 2

Your tongue can detect voltages from around 3 volts and up.
About 9 volts should be about the limit. It will not detect value, but will detect presence. Of course the sharper the sting, the higher the, ouch, voltage.