You've probably heard the old adage that nothing in life is free. The idea is that even if something doesn't cost you dollar bills, it will cost you time, or effort, or a little piece of your soul. The same is true for the App market, as a new study claims that running those freebies can cost you sweet, precious battery life.

BBC News reports that Android and Windows Phone devices loading up third-party advertising utilities in free apps took a serious hit to devices' power. The study used popular free apps like Angry Birds and Facebook over a 3G connection.

The study suggested that only 20% of Angry Birds' energy usage was to run the actual game. 45% is used to locate you so that the third-party tools can target their advertising. At least another 25% was eaten by the "3G tail," a period of time up to 10 seconds in which the 3G connection is kept open even after the download has completed.

"Advertising needs to connect to the server and send information about location," said Chris McClelland of app developer Ecliptic Labs. "That just takes up so much battery. It seeps up the energy."

The researchers didn't test Apple devices like the iOS and iPad, but if your apps are pulling advertisements using a 3G connection, it seems likely you're getting a loss of power no matter which platform you use.