I wonder if anyone here can help. I'm merely a casual user of Wolfram Alpha, using it primarily to indulge in whimsical thoughts and day-to-day questions that come to me all of a sudden. In this vein, I've been wondering about the battery life of the average cell phone, and how much this has increased (or indeed decreased) since the invention of this device.

Naturally I turned to Wolfram Alpha in the hope of creating some sort of battery life chart or graph over the decades. But sadly I just can't seem to phrase things in the right way. The only progress I've made is a result for "length of cell phone battery life", but one average point of data does not make a chart! Any ideas?