Voltage is a measurement of a battery's power. The higher a voltage, the more powerful a battering is. 1.5 volts barely hurts at all. Higher voltage batteries such as 9 volt batteries should be approached with caution. 12 volts is exceptionally painful, causing electrical burns and bruises. Large groups of batteries should be avoided at all costs. The highest known combined voltage is 250 volts which is extremely lethal and able to kill 4 humans simultaneously. Just try connecting 5 batteries(12 volt)in a series circuit, remove the protective coating from the wire, and touch it with a wet hand. Try it.