“It could work!”
Some months ago, researchers at Stanford University have published a paper about a new technique, named “PowerSpy”, that has capability to gather the geolocation of Android phones by simply by measuring the battery usage of the phone over a certain time.
Unlike Wi-Fi and GPS access, the battery consumption data does not need the users’ permission to be shared and is freely available to any downloaded and installed application.
Therefore, this data can be used to track a phone with up to 90 percent accuracy.
You can read more informations about the research on this site:
Aggregate phone power consumption data is extremely noisy due to the multitude of components and applications that simultaneously consume power. Nevertheless, by using machine learning algorithms we are able to successfully infer the phone’s location. We discuss several ways in which this privacy leak can be remedied.
Researchers have also released the source code of Android software used for data gathering on BitBucket:
But…also with HTML5 i can access battery data!
Yep! The W3C Battery Status API allows a web site to read the battery level of a device and the researcher Lukasz Olejnik has published a blog post saying that advertising companies are currently leveraging the potential of this battery status information:
Expected or not, battery readout is actually being used by tracking scripts, as reported in a recent study. Some tracking/analysis scripts (example here) are accessing and recovering this information.
Additionally, some companies may be analyzing the possibility of monetizing the access to battery levels. When battery is running low, people might be prone to some — otherwise different — decisions. In such circumstances, users will agree to pay more for a service.
As a response, some browser vendors are considering to restrict (or remove) access to battery readout mechanisms.
Olejnik has published a paper about this research. I suggest the reading: