The reality discovered by many developers is that, given a choice between a for-pay app and a free ad-supported app, users will chose the free app 100 times more often than the pay app.
Now Microsoft Research has shown there is no such thing as a free lunch. By analysing free ad-supported Android apps they were able to show the ads displayed when the app is active can consume much more battery life than the app itself, saying running just one app could drain your battery in around 90 minutes.
The culprit is location-based ads, which get your location using GPS, already notorious as a battery drain, and then download ads over an open 3G connection.
For example, in Angry Birds only 20 per cent 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.
When they looked at popular Android apps such as Angry Birds, Free Chess and NYTimes they found that only 10 to 30 per cent of the energy was spent powering the app’s core function.
The solution, according to Abhinav Pathak, the lead researcher from Purdue University, Indiana, was not to get rid of ad-supported apps, but to optimise the code of the 3rd party ad SDKs for battery life also, no an issue that has been considered before.
Pathak will present the research at the EuroSys conference in Bern, Switzerland, next month.