Ryan Whitwam reports on the ExtremeTech website that researchers have found a way to track android phones by studying their power use over time.
The technique works on the principle that the further away a phone is from a base station, the more power the phone uses to maintain a connection. Researchers called their proof of concept application PowerSpy. Before it can be used a power map of an area has to be established so that PowerSpy knows what performance to expect in a particular location.
Although making a call or using apps will also drain power, the algorithm used in PowerSpy is designed to monitor power use over several minutes, so that battery usage not associated with location can be filtered out.