Although mobile devices are constantly becoming faster and more efficient, battery drain is an issue that seems to continually plague app developers. The reason is simple: Users are attracted to dynamic apps that offer impressive visuals, extensive functionality, and that run fast. Unfortunately, many developers don’t know how to deliver this while also keeping their app from draining users’ batteries. And since battery life is the one resource that is shown on the screen constantly, using too much can ruin even the most useful apps.
So how can you create an effective app while also avoiding battery drain? While some developers may immediately begin pairing back key performance metrics like frame render rates, this can adversely affect the usability. Fortunately, there are several creative ways to ensure your app remains effective while keeping it from consuming too much battery.
Using a wake lock to keep a phone’s screen or CPU on is one of the most common ways an app will drain a battery. Although they may sometimes be necessary for an app to carry out a function, too often they are not. However, if you do need to prevent a device from falling asleep, there are several lightweight alternatives to wake locks that you should consider first.
For example, if you need to keep the screen on, use the FLAG_KEEP_SCREEN_ON function. This does not require any special permission and allows Android to manage unused sources when the user moves between applications. Alternatively, if your app is performing long-running HTTP downloads, you can use DownloadManager to conduct the download in the background. Or, if your app is synchronizing data from another server to create backups, you can use Android’s sync adapter framework. This gives you more control over battery usage by centralizing data transfers so that they all run at once.
If your application does require a wake lock for certain essential components, such as the CPU, consider using PARTIAL_WAKE_LOCK so that users can at least shut off their screen.
A golden rule of writing code is that you should never be doing work that you don’t need to do. The same goes for your app. To keep it from using up too many resources, you should carefully comb through its code to ensure that it is not dragging down performance and battery life. As you do this, ask yourself whether each operation can be removed altogether or deferred. For instance, can your app cache data rather than repeatedly download it? Can data backup wait until the device is getting charged?
How you optimize your application will ultimately depend on its unique needs. However, there are multiple tools available that can help you tweak your app to maximize battery life. One of the most useful is JobScheduler, which allows you to intelligently schedule different tasks to better manage device battery consumption. Rather than making your app dependent on user interaction, you can program it to carry out nonessential functions, such as downloading information or updating itself, when it has access to a network or power source.
A surefire way to drain your users’ battery is to build an app that continually wakes up their device to perform operations. This is especially true when it comes to network operations, as a device’s wireless radio is one of the most significant sources of battery usage. Every time a typical 3G radio is powered on for a data transfer, it will remain at a full energy state for an additional five seconds of tail time, followed by another 12 seconds of low energy state. This means that, if your app transfers data for one second every 18 seconds, the radio will remain perpetually on.
The simplest way to fix this issue is by batching your operations so that they all turn on and utilize the radio at once. This can be done for both outbound data transfers, such as when an app needs to transmit information to an external server, or for inbound data transfers. For the latter, you can use prefetching, which allows you to download all the data you will need for a given session at once, rather than through multiple transfers, helping you to effectively cut down the total number of times the radio is turned on.
If you’re still looking for more ways to reduce battery use, Android offers an array of options for optimizing how your app handles two of the worst offenders: network usage and location services.
For instance, to reduce network battery drain, the first step is to collect and analyze traffic data so that you understand how your app is using network resources and consuming power. This will allow you to optimize app network use over multiple workflows, including user-initiated, app-initiated, and server-initiated. Learn more on Android’s Reduce Network Battery Drain page.
Optimizing location services is another great way to improve your app’s battery life. To do this, you can tweak how your app the precision of its location data (accuracy), how often it collects location data (frequency), and how quickly it collects location data (latency). In general, the higher any of these factors are, the more battery your app will require. Depending on your needs, you may be able to optimize battery usage by reducing the location services your app uses. Learn more on Android’s Optimize Location for Battery page.
Finally, Android offers multiple other features to further reduce app power consumption. Doze takes advantage of batching by deferring activities while the device is asleep and consolidating them to maintenance windows. If a device is inactive over a long period of time, these maintenance windows will become less frequent, helping to save battery. AppStandby also takes advantage of inactivity, except (as its name implies) it focuses on individual apps. If an app has not been used for a period of time, it will halt all of its network activity.
While it may be tempting to take shortcuts that reduce overall app performance in order to optimize battery consumption, it is not necessary. Creative developers now have many ways of making sure their applications are using power intelligently while also meeting the needs and expectations of their users. Keeping these considerations in mind throughout development will help increase the success of your app.
Stay tuned for more tips and tricks for making apps better.