The recent launch of the Apple iPhone 14 series has catapulted the 'always-on display' into consumer consciousness in a big way. Although new to Apple devices, the technology has been part of the Android world for years. But what exactly is it and how does it affect battery life? Our DXOMARK display and battery experts conducted research to better understand the autonomy impact of Always-On technology.
The display is a very energy-consuming part of a smartphone. This causes most smartphone screens to turn off after a relatively short period of inactivity. The "always-on" feature allows users to view certain types of information, such as the time, without having to fully wake the phone from sleep.
DXOMARK recently asked users in a survey* what they thought of the Always-On feature, and 54% of respondents said they found the feature useful, while 46% found it not very useful.
However, the convenience of having the screen lit all the time can come at the expense of battery life, and that's one of the main things our engineers wanted to figure out. So they tested the brightness and power consumption of the always-on displays of four leading devices: Apple iPhone 14 Pro Max, GooglePixel7 Pro, Samsung Galaxy S22 Ultra (Exynos) and Xiaomi 12S Ultra - for a fair comparison.
Our tests
To perform our battery measurements, we tested all four smartphones under the same conditions for at least two days in a Faraday cage at a temperature of approximately 22°C (71.6°F), with ambient light of 50 lux and battery power between 20% and 80% (levels at which the battery meter is most stable). The telephone settings were also the same everywhere:
- ·Airplane mode enabled
- Wi-Fi, data, Bluetooth, location services (etc.) are disabled
- Auto brightness on
- Adaptive refresh rate is enabled
· All units used a graybackground(on the default screen, not specific to Always On), but this only affected the iPhone, which shows the wallpaper blurred when Always On mode is enabled
To perform the display measurements, we used a Radiant imaging colorimeter to map the always-on interface and base our calculations on the maps.
From left to right: Apple iPhone 14 Pro Max, Google Pixel 7 Pro, Samsung Galaxy S22 Ultra (Exynos), Xiaomi 12S Ultra
Measure battery
Our battery test results showed that autonomy was greatly affected by this always-on feature, which drains the battery about 4 times faster! The battery lasts about 100 hours in idle mode when the feature is activated, instead of 400 hours when the feature is disabled. The Google Pixel 7 Pro had the best autonomy of the four devices, lasting 139 hours when the Always On Display was activated. Interestingly, the smartphones with the best autonomy in idle mode also showed the worst autonomy when turning on the Always-on display. Is it too much confidence in their battery that the manufacturers spent less time optimizing this mode? Maybe.
*Qualifies the autonomy in hours until complete discharge of the battery. This data is projected thanks to a long measurement taken between 80% and 20% of the battery, where the battery is most "stable". Combined with linearity we can project the autonomy on a full battery.
At DXOMARK, in addition to autonomy measurements, we compare power consumption, in milliamps (mA), which is the ratio of battery capacity (mAh) divided by autonomy (h). This metric measures the rate at which a specific use drains the battery and evaluates the performance of the platform itself, regardless of battery capacity. As shown in the following table, the iPhone is the most optimized and the discharge current remains low in all situations. But the differences with the competitors are quite small, with discharge currents around 10mA in idle screen off and around 36mA with always on screen, except for the Xiaomi 12S Ultra, which drains the battery much faster at 47.3mA. Why? You will find some explanations in the analysis of our Display experts.
*Discharge current is the ratio of battery capacity divided by autonomy (for more details on how we measure discharge currents, see the DXOMARK How We Test section on dxomark.com: https://www.dxomark.com/a-closer-see -how-dxomark-tests-the-smartphone-battery-experience/)
Show goals
As for the results of our screen brightness test, the iPhone 14 Pro Max and Xiaomi 12S Ultra were the brightest of the four devices by quite a large margin. But the difference is big when it comes to the way the screen lights up. In fact, the Apple iPhone 14 Pro Max lights up the entire screen, while the Samsung and Google devices only light up the icon. The reason that the Xiaomi 12S Ultra has a very high maximum and average brightness is that in Always-On mode it also shows a very bright symbol in addition to the time of day.
Acquisition of Radiant imaging colorimeter shownBrightnesslevels on the different displays in our study
Another important point is that all these devices use OLED screen technology, which is more energy efficient because, for example, black areas on the screen do not consume power. LCD technology, on the other hand, always consumes energy and is therefore not compatible with Always-On mode. Therefore, bright devices are expected to have higher consumption. Note that we were unable to make specific measurements on the variable refresh rate, as the luminance is very low in automatic mode. But the refresh rate can affect battery life depending on how it is set by each manufacturer.
To conclude our measurements, we found that although the iPhone had an average brightness screen, its power consumption was the lowest, indicating that Apple engineers have optimized efficiency very well. Google and Samsung showed similar power consumption, but with an Always-On Display experience that was much less demanding: only small parts of the screen were illuminated and the maximum brightness was kept low. They both showed similar discharge currents to the iPhone, while showing a much dimmer display.
Finally, the third Android device, the Xiaomi 12S Ultra, showed the highest battery consumption when the Always-On feature was enabled, and although its average brightness was comparable to iPhones, the battery consumption can be explained by the very bright pixels on the side. characteristic icon. The maximum brightness was by far the highest.
Ultimately, the resulting user experiences in terms of autonomy were quite similar, as the Android devices have a larger battery capacity than the iPhone.
Room for further optimization
Apple was late to offering an 'always-on display' feature like its peers, but as with virtually every feature the company launches, its engineers have thoroughly researched how to optimize the user experience by making the most of the hardware and get the operating system. The always-on experience on Android phones, which have had this feature for a while, isn't quite on par with iPhones, offering an almost comparable or worse battery experience. The performance of the iPhone 14 Pro Max shows that further optimization is also possible for Android phones.
*DXOMARK survey conducted on social media (Twitter and LinkedIn) from November 30 to December 12, 2022; the results are based on responses from 222 people.
