iPhone 4 and iOS 4 battery drain

Anthony Caruana
Wednesday, 04 August 2010 13:14

Your IT - Mobility

iPhone 4 owners and those that have upgraded their older iPhones to iOS 4 have noticed that battery life is suffering. We take a look under the covers to find the problem.

One of the big features that Apple has delivered with iOS 4, that was requested by users, was multi-tasking - applications continue to run in the background even when you've returned to the home-screen or another application. Here's an example of how it works.

If you're running a sat-nav and then decide to go to the browser to look something up, the sat-nav app continues to run in the background, tracking your movement and updating its route information. With any application that uses Location Services, it's easy to see this running as there's a small indicator near the battery meter at the top of the screen.

However, other applications are more insidious. For example, we were running an IM client, Yahoo Messenger, and found that it was running in the background, churning up CPU cycles. An easy way to check which applications are running under iOS 4 is to double-press the main button. That opens a small tray of your running applications.

This list scrolls across with a finger swipe and shows which applications are currently active on the iPhone. Based on our observations and use, it's easy to end up with over a dozen apps all sitting there, either working or waiting for some further input from you.

If you want to really shut down an app, a tap-hold on the open application icon will reveal a small minus sign in the top-left corner of the icon. Tapping that will close the application down.