ONE of the most annoying features of smartphones is that they run out of power just when you need it most. After a day of e-mailing, streaming music, downloading podcasts, watching cat videos and snapping selfies, a device can easily be left without enough charge to make an emergency call. What would help, reckons Paul Worgan of the University of Bristol, in England, is to give portable devices the ability to share some of their power.
Mr Worgan and his colleagues have come up with a wireless-charging system which they call PowerShake. To use it someone holds a phone with an expiring battery against another device—a phone, or even a smartwatch or a fitness band—and this initiates a power transfer from one to the other. Some 12 seconds of contact provides enough juice to make a one-minute telephone call. One minute of contact would allow, say, a four minute music video to be watched. The researchers will present their idea to CHI2016, a conference on computer-human interaction, in San Jose, California, in May.
Initially, the Bristol team have opted to customise the Qi coil for PowerShake experiments. They cannot use the existing Qi format because it is not designed for inductive charging next to human skin. So, to conform to international regulations, they are looking at including a ferrite and copper shield between the coil and someone’s skin, which is necessary on devices like a fitness band or smartwatch.
In testing their idea out, however, the researchers ran into a less technical problem. Some people said they were reluctant to offer their precious battery charge to others. A form of inducement might help. Vassilis Kostakos, a computer scientist at Oulu University in Finland, says one answer is cash. Anticipating the arrival of technologies like PowerShake, Mr Kostakos and his colleagues set up an auction for device power with 22 volunteers. The results, also due to be released at CHI2016, showed people wanted €1.76 ($2.00) to sell 10% of their device’s power when their battery was fully charged, but €4.41 to offload 10% when the charge had depleted to 20%. On average, 10% of device power sold for €2.22. Of course, if you appear desperate to see that cat video, the price may go up.