No longer will your phone running out of juice be a problem: providing you are prepared to have a quick run. New gadget AMPY converts energy from motion into battery life to charge any USB-powered device.

A 30-minute run, 10,000 steps or an hour’s bike ride is enough to charge a smartphone for three hours. The battery can store about a week’s worth of physical activity and stays ready to use for months.

An associated app tracks the amount of energy generated, calories burned and carbon footprint offset. Individuals can also compare their stats with other users via social media.

Developed by a team of engineering PhD students in America, AMPY’s co-founders say they hope the technology behind the device will be directly integrated into smartwatches, fitness trackers and other devices yet to be invented, so they never have to be plugged in.

Wearable tech is predicted to hit the mainstream by 2016, with a forecasted 180 million units to be sold, driven by products such as Sony SmartWatch, Samsung Galaxy Gear, Microsoft Band, Apple Watch and Google Glass.