he first large-scale study of smartphones in everyday use by consumers has revealed that apps drain 28.9 percent of battery power while the screen is off. To address the problem, researchers have created a software tool that reduces the energy drain by about 16 percent.

Researchers at Purdue University, Intel Corp. and startup company Mobile Enerlytics 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,” said Y. Charlie Hu, a Purdue professor of electrical and computer engineering.

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 at http://www.github.com/hushnymous

Source: New tool reduces smartphone battery drain by intelligently suppressing background activities – Purdue University

It’s not an app yet, but could be soon – hopefully.