Ads in free Android apps might be annoying but you probably never imagined they were radically draining your battery. New research from Purdue University and Microsoft highlight just how much ad-driven apps tank your battery life.

What did they find? That poorly designed ad-modules in free ad-driven applications are terrible at conserving energy. In popular applications like Angry Birds and Free Chess 70% of the energy the application consumed was used to drive the ads. They also surveyed other applications and found that ad-driven apps weren’t alone in excessive battery use–the New York Times app, for example, spent 15% of its battery consumption on tracking and background tasks.

Hit up the link below to read the full whitepaper for a more in depth look at the methodology and results.

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