How to Make Your Battery Last Longer – Turn Off Chatty Apps, Part 2

In my last post I showed you research on battery drain. This time I’ll give you a look at turning off chatty apps, both before and after using Trepn™ Profiler, a product of Qualcomm Technologies, Inc.

How Many Apps Are On Your Phone?

First, the math I showed you last time from Google I/O assumed 30 apps installed on a smartphone.

That may seem far-fetched to some people, but a report from Statista and Mashable based on data from Google’s Our Mobile Planet project shows that, globally, the average smartphone has 26 apps installed. In the United States, the average smartphone has about 33 apps installed, and in South Korea the figure goes up to 40 apps installed. That’s in line with the calculations on how quickly apps devour battery life.

Don’t forget that in some cases users have no control over the apps draining the battery. Between the handset manufacturer and the carrier, most smartphones come with a handful of preinstalled apps for things like location, news, weather and media that chisel away at battery life, but which users can’t remove, short of rooting the device.

So by default, smartphones come ready to consume power just about any way they can.

Using Trepn Profiler – Test 1

Take for example the up- and down-arrows on your phone’s menu bar. They flash even when you’re not using your phone because installed apps are using the cellular radio to send and receive data, which consumes power.

Trepn Profiler is designed to collect activity data from different functions on the device, then lets you analyze it on your mobile device or PC. I used Trepn Profiler to see what my phone was doing while it sat idle on my desk for an hour.

1. I downloaded Trepn Profiler from the Qualcomm Developer Network and installed it on my phone.
2. To see whether apps were using the cellular radio in my device efficiently, I turned off WiFi.
3. I launched the app on the device and touched the Profile System button.
4. To make sure it was all about the radio, I turned off the screen and left my device unused for about an hour.
5. After 60 minutes, I stopped profiling, saved the data as a database file and copied it to my computer, which runs the Trepn Plug-in for Eclipse. Here’s the resulting chart (with my notes):

• The red chart shows that even though I wasn’t using my phone, two of the CPU cores were active much of the time, spiking to almost their maximum operating frequency.
• The orange chart shows the GPU was also used at least four times at about 70% of its maximum operating frequency.
• The light yellow line shows the GPS was turned on and off three different times, even though the phone was not in use, so apps were asking for and likely storing my location.
• But the biggest revelations are on the light green chart (Mobile Network State) and the Mobile Data Usage chart beneath it. The radio is idle, but it’s almost never dormant. Packets are coming and going almost constantly, so the radio stays on for a few seconds after each transfer, as I described in the last post.

I may not have been using my phone, but something was.

Using Trepn Profiler – Test 2 (Chatty App Turned Off)

I had a hunch that a particular social app was the source of all the activity, so I disabled updates on it and repeated my experiment, this time for 30 minutes.

• This time, the red chart shows that average clock speed dropped and, at some points, the number of active cores dropped to one.
• The light green chart shows that the cellular radio still never reached its low-power, dormant state and was transmitting at full power for over 400 seconds. This generally indicates that apps are mismanaging the cellular radio.
• Note that this time, the Mobile Data Usage chart shows that the phone moved only about 10-20 percent of the number of packets in the first test.

Next Steps

If you’re a developer, you can use Trepn Profiler to profile the apps you create. The resulting charts show you how particular functions in your app affect components on the mobile device – CPU, GPU, Wi-Fi, cellular radio, display, etc. – and ultimately affect your customers’ battery life. Plus, on Snapdragon® Mobile Development Platforms, you can chart the power consumption of your app all the way down to the battery level.

Whether you’re a developer or a user, Trepn Profiler is an easy-to-download and easy-to-use tool for monitoring app performance. Following my example above, you can use it to test your device with certain apps disabled until you determine which ones are consuming power needlessly.

• To get access to Qualcomm's multiple mobile development technologies, you need to register on the Qualcomm Developer Network
• Get Trepn Profiler now from the Qualcomm Developer Network.
• You can find out more about using Trepn during my presentations at AnDevCon in San Francisco (this Wednesday, November 19 at 11:30am). Stop by, introduce yourself and let me know what you’re working on.