A battery is a power source consisting of one or more electrochemical cells with external connections. They are used for powering electrical devices such as flashlights, mobile phones, and electric cars. Italian physicist Alessandro Volta is generally credited with discovering the first practical battery. He invented his battery in 1800, it consisted of discs of two different metals, such as copper and zinc, separated by cardboard soaked in brine (high-concentration solution of salt NaCl in water H2O). However in the present we have portable rechargeable batteries with many advanced features.