There's more and more evidence that the Pixel 4's battery is too small and Google's path to acceptable battery life limits software capabilities through its ability to run. The latest discovery comes from Mishaal Rahman of XDA Developers, who found an unused high-brightness mode hidden in Pixel 4's code.
A high brightness mode has become a typical feature of smart phone display panels. Instead of a special toggle switch, manufacturers usually enable a high-brightness mode when the user turns the brightness slider all the way up or when the ambient brightness sensor detects sunlight. This usually has a negative effect on the battery life. However, if you have the choice of seeing or not seeing your phone in direct sunlight, the tradeoff between runtime is a welcome option.
The Pixel 4 display is not particularly bright with a peak brightness of around 450 nits in full-screen mode. The Galaxy S10, on the other hand, has a maximum frame brightness of 800 nits, and a big difference seems to be the lack of this increased brightness mode. Rahman found the pixel 4 high brightness mode hidden in the pixel 4 kernel, but it is not a mode normal users can freely switch to. It does not turn on via the slider or in high ambient light.
As usual, Rahman has found a way to turn the feature on and off with root access so that Pixel 4 achieves a more acceptable peak brightness of 610 nits. It sounds as if flipping the switch will cause it to work just like a Samsung phone – just open the brightness slider so the maximum setting emits more light.
This is the second big discovery around the Pixel 4 Wonky display implementation. Pixel 4 should have a "Smooth Display", which indicates the 90 Hz functions of the panel. However, unlike any other 90Hz phone on the market, Pixel 4 does not always run in 90Hz mode. Instead, Google has tied the refresh rate to the display brightness and ambient light so that the "90Hz" pixel 4 runs most of the time in 60Hz mode. According to Google, the 90 Hz mode was limited to "conserve battery", so probably the brightness restrictions were applied according to the same considerations.
The battery of the Pixel 4 is since the announcement of the phone a big problem. The smaller Pixel 4 has only a 2800 mAh battery, a downgrade from the Pixel 3's 2915 mAh battery and is much smaller than the Galaxy S10's 3400 mAh battery. For a Samsung flagship with a battery that is comparable to the Pixel 4, you would have to fall back on the now five-year-old Galaxy S6. The Pixel 4 XL is a little better with a 3700 mAh battery compared to the 4100 mAh battery from Samsung, but still not competitive. Note that these phones have the same price when comparing comparable storage options.
Following the limitations of 90 Hz mode, Google has released a November patch that works 90 Hz in slightly brighter conditions Pixel 4 runs most of the time in 60 Hz mode. Maybe we'll get a patch soon, which will cancel the brightness.