In my previous blog post Saving battery power on Android: Third-party apps and wake locks, I discussed a battery-saving tip that works and is important for users to know about.
Here, we’ll look at a few common tips that don’t work.
Disabling PUSH notifications
You won’t gain much from disabling PUSH notifications. In fact, PUSH notifications can easily be more battery-efficient than polling. This is because your phone is able to listen for them even while sleeping (CPU off). A tiny bit of power will be spent on processing any incoming PUSH notifications, but that’s it. For those interested, the framework that makes this possible is called C2DM. Many instant messaging apps use this technology to enable the user to be connected to chat services even while the phone is sleeping.
As is often the case, no rule without exceptions. Android doesn’t enforce the use of C2DM, so you may occasionally encounter apps that implement PUSH notifications in a more battery-intensive manner.
Using task killers
Generally speaking, there is no point in using task killers. Properly written Android apps become idle when entering the background. They may be kept in memory for a while and appear to be running, but they aren’t using CPU cycles. If memory becomes low, Android will automatically close unused apps to free up memory. This is not something that the user need worry about.
If an app becomes unresponsive, you may need to kill it. But you don’t need a third-party task killer for this; You can do in Settings –> Apps.
Data through WiFi uses less power than 3G, so if you have WiFi available, by all means use it. A steady WiFi connection uses very little power. In Android 4.0, go to Settings –> WiFi –> Three dots –> Advanced –> Keep WiFi on during sleep –> set to “Always” (this should be the default, too).
When you’re in an area without WiFi, however, I suggest disabling WiFi altogether so the phone doesn’t waste power searching for networks. You may want to add a widget to your home screen for easy access to a WiFi switch.
Globally disabling the GPS feature
The GPS chip is only powered up when an app requests a GPS location, so there’s usually no serious gain from disabling GPS altogether. You may save some power when using location-aware apps, but you will also be forcing them to use the less-accurate network location instead of GPS.
How to actually save power
Besides my own blog post on the subject of wakelocks, this Lifehacker blog post has some decent tips on how to save power. It does, however, advocate the use of certain third-party apps to manage battery life – I’ve never personally felt the need to use such apps.