Cell Phone Doesn't Need a Battery ... for 15 Meters

Sick of watching your mobile phone drop from 40% to dead in the space of a minute? (*grumble*) How about a cell phone that doesn’t need batteries? Sorta ...

Vamsi Talla, a research associate at the University of Washington in Seattle, developed an interesting prototype which uses analog technology to make voice calls and text without batteries. The catch – it has a range of just 15 meters (from the basestation).

"Converting analog human speech to digital signals consumes a lot of power," noted Talla. "If you can communicate using analog technology, you're actually more power efficient."

As Wired points out, Talla and his team developed a passive “backscatter” process that reflects incoming radio waves to dial numbers. And the voice calls, themselves? Pure analog.

Talla quickly realized the parallels between his passive technique and a similar technology from the Cold War. In 1945, the Soviets presented the Americans with a present containing a secret audio bug, which only responded to the correct frequency of radio waves.

Because the backscatter process relies on components housed elsewhere for its passive power requirements, the prototype has a limited range of 15 minutes. Though if the tech were incorporated into cell towers, the phone could drift up to a kilometer.

And if many cell towers housed these components, we might realize our dream of cell phones unencumbered by irksome batteries.