Phone batteries are considered as the heart of the telephone. A phone can’t work without their engines (battery). 

Though they are not on the outer part of the phone to gain visibility, their roles are to essentially store chemical energy that is converted into electricity to power the device. 

But before we talk about the phone battery, let us trace the origins of the battery itself. 

History suggests battery have for a long time been with us, because in 1938, the Direct of the Baghdad Museum found a battery, currently referred to as the "Baghdad Battery” in the basement of the museum. Analytics dated it back to 250BC in the Mesopotamian origin. 

But the first battery was named by an American scientist, Benjamin Franklin who used the word, "battery” in 1749 doing his experiments with electricity using a set of linked capacitors. 

In 1800, an Italian physicist Alessandro Volta invented the first battery as he stacked the discs of Copper and Zinc. 

Batteries kept evolving and gaining fame, until the phone was discovered and its battery was needed. 

The first prototype of what would be considered a modern cell phone battery was first created and by 1973, it was being tested in Baltimore, Washington D.C. The tests were also being conducted in Japan simultaneously. 

However, the results of those tests produced highly powered devices that wouldn’t fit in a pocket and takes 30 minutes of charging at their best. 

Before that, a smaller phone battery wouldn’t be produced because cellular phones at the time were very large and bulky devices with an antenna that needed to work manually. This big size was a result of a bigger battery that even took little time to completely run dry and be charged again.

Since the introduction of smart phones in 2000, external battery charges have become today’s ideal because modern phones need to be used more often.