Here's an interesting one if you're one of those folks who doesn't like to pay for smartphone apps - those free ones may be draining your battery faster than premium ones.
We realise that's quite a generalisation to make but it is based on some research - research that has been picked up on by New Scientist.
Those behind it found that 10-30 percent of the power drawn is for the app itself with the rest going on driving the advertising which ultimately pays for the app.
We're not talking some rubbish you'll find in the depths of Android's PlayShop here but also some big names - like Angry Birds, which only used 20 pecent of power to fuel the game but an amazing 45 percent to generate location-specific ads. Strewth.
Then there's the additional power demands of the 3G connection needed to utilise all this jiggerypokery.
As they say, no such thing as a free lunch!