Free Apps Drain Smartphone Batteries

Paying for your applications can make your smartphone battery last longer, according to research.

Almost 75 percent of the energy consumed by free versions of apps is exhausted serving up ads, tracking user information and conducting other hidden tasks, unrelated to the application’s core functions, according to the study, entitled “Where is the energy spent inside my app?” by computer scientist Abhinav Pathak of Purdue University, Indiana.

Eating power

Pathak and his colleagues made the discovery after developing Eprof, which they claim is the first fine-grained energy profiler for smartphone apps. Eprof was then tested on smartphones running Android and Windows Phone 7, with the notorious iPhone battery life eluding judgement.

When the team of researchers looked at six popular apps including Angry Birds, Free Chess, Facebook and NYTimes, they found that only 10 to 30 percent of the energy was spent powering the app’s core function.

“For example, in Angry Birds only 20 percent is used to display and run the game, while 45 per cent is spent finding and uploading the user’s location with GPS, then downloading location-appropriate ads over a 3G connection. The 3G connection stays open for around 10 seconds, even if data transmission is complete, and this “tail energy” consumes another 28 per cent of the app’s energy,” reports New Scientist.

Eprof also revealed several “wakelock bugs”, a family of ”energy bugs” in smartphone apps, and effectively pinpointed their location in the source code.

Pathak blames the energy leakage on inefficiencies in the third-party code that developers use to generate profit on free apps.

“Despite the incredible market penetration of smartphones and exponential growth of the app market, their utility has been and will remain severely limited by the battery life. As such, optimising the energy consumption of millions of smartphone apps is of critical importance,” reads the research paper. “However, the quarter million apps developed so far were largely developed in an energy oblivious manner.”

Since the problems are in the code, they can be fixed fairly easily. Using a new accounting presentation of app I/O energy, Pathak’s team has managed to reduce the energy consumption of four apps by 20 to 65 percent.

The research findings will be presented at the EuroSys conference in Bern, Switzerland, next month.

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