Apps drain 28.9 percent of smartphone battery power while the screen is off, according to the first large-scale study of smartphones in everyday use.
To address the problem, researchers have created a software tool that reduces the energy drain by about 16 percent.
Researchers studied the use of 2,000 Samsung Galaxy S3 and S4 phones served by 191 mobile operators in 61 countries. “This was the first large-scale study of smartphone energy drain ‘in the wild,’ or in everyday use by consumers,” says Y. Charlie Hu, a professor of electrical and computer engineering at Purdue.
Out of the 45.9 percent of daily battery drain where the screen is off, 28.9 percent is due to apps that frequently wake up and run in the background. Out of this 28.9 percent, researchers have shown how to save 15.7 percent with a new system called HUSH, which is available for free on GitHub.
“During screen-off, the phone hardware should enter the sleep state, draining close to zero power,” Hu says. “Apps wake the phone up periodically during screen-off to do useful things, but then afterward, they should let the phone go back to sleep. They are not letting the phone go back to sleep because of software bugs and, specifically, due to the incorrect use of Android power control application programming interfaces called wakelocks.”
