Battery and meters are two widely used technologies, yet no one stops to think how they work. They determine our future. They dictate how we communicate, commute, adopt green technologies, and measure. Imagine the trauma of pushing your snazzy car everytime you started on a journey, or charging your new cell phone after each call. And what would the world be without the means to calculate the amount of resources used? Bharat Lal Seth charts the evolution of the two technologies and analyses what future holds for them