ASUS Eee Pad Transformer Prime Power Modes Tested: Which Gets the Most Battery Life?

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Among its other attributes, the ASUS Eee Pad Transformer Prime has two unique features that will help users extend its battery life: The ability to switch the screen from Super IPS+ to Standard IPS mode, and three performance settings: Power Saving, Balanced, and Normal. But how much more battery life can you squeeze out of the Prime?

First, an explainer. In Standard IPS mode, the Transformer Prime maxes out at an extremely bright 380 nits, but when you enable Super IPS+ mode, that number jumps to 600 nits.

For the performance settings, in Normal mode, all four of the Tegra 3 CPU's cores can operate at their maximum speed of 1.3 GHz; in Balanced mode the cores are capped at 1.2 GHz. Power Saving mode caps the cores at 600 MHz when all four are active, 700 MHz when three are active, and 1 GHz when one or two are active. It also caps the frame rate at 35 fps and lowers the display power.

So, with two brightness settings and three performance settings, that's six possible permutations. And we've tested them all. 

To test the Transformer Prime, we used our standard LAPTOP Battery Test, continuous web surfing via Wi-Fi with the screen brightness at 40 percent. Also, these tests were conducted with the tablet alone, and not when connected to its dock.

As was expected, the combination of Power Saving and IPS gets you the longest runtime, while Super IPS and Normal eats up the battery the fastest. However, we were a little surprised that there was almost no difference between Normal and Balanced mode when using Super IPS mode. As ASUS said, most users will see the best combination of power and endurance using Balanced mode. 

Stay tuned for our battery tests of the Prime using its keyboard dock.


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1 comment
  • Damien R. Says:

    The Norman/Balanced result makes perfect sense with the kind of test you ran. The difference between the two is the maximum speed at which the cores can be set. Your test uses very little CPU, and probably only the 5th core (the one for "regular use"). Little CPU means the difference in max clock speed between Norman and Balanced is negligible, hence your results. Another reason for the little difference is that one of your power drains is the Wi-Fi, and the Wi-Fi will drain the same kind of juice in any power/brightness mode with the kind of test you are doing.

    Repeat your Brightness vs. Power Saving mode tests using a test such as "continuous playback of a 720p movie" which WILL use the 4 cores of the Tegra 3, and then, you should see some differences.

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