A definitive guide to everything that affects smartphone battery life

Here are all of the things that can contribute to bad battery life.
You’ve no doubt seen or read many articles online about saving battery life. It’s a popular topic because nobody likes tethering a phone to the wall multiple times a day. However, most battery-saving articles give you ideas about what to try in order to improve your battery life. This time around, we’re instead going to identify all of the various things that cause battery drain in smartphones.


The list is actually surprisingly long and that’s probably a good indicator of why so many people struggle with battery life. It is difficult to keep track of every little thing your phone does. However, we hope that giving you this knowledge will help you troubleshoot battery issues and adjust your usage to maximize your battery life. Here is our definitive guide to everything that affects smartphone battery life.


Battery sizeOnePlus 10 Pro top view showing battery statsWe’ll start with the most obvious influence on battery life — the size of the battery itself. Not all smartphones have the same battery size and it’s this size that helps determine how long your phone will go before hitting zero. Smartphone batteries are generally measured in milliamp-hours (mAh). This is mostly simple math. The more mAh a phone has, the longer it should be able to theoretically last. It doesn’t always work that way, but it’s a good place to start.


On the high end, phones like the Samsung Galaxy S22 Ultra and the Moto G Power have massive 5,000mAh cells while some other phones, like the regular Galaxy S22’s 3,590mAh battery, have smaller cells. Generally speaking, phones with larger batteries tend to have better battery life than ones with smaller batteries.
Of course, there are many other factors to take into account. More powerful processors and larger, high refresh-rate screens will drain your battery faster. More on those factors below. However, if the phones have identical specs, the one with the bigger battery will simply last longer.


DisplaySamsung Galaxy S22 Ultra vs Apple iPhone 13 Pro Max front on carpetThere are four different ways a display can affect battery life. The first is the size, as larger screens have more surface area and require more power to light up. Phones with larger displays also usually have larger batteries so there is a bit of a give -and-take there.
The second way a phone’s display affects battery life is the resolution. Admittedly, the differences aren’t huge, but it is objectively measurable. Displays with 1440p resolution have 77% more pixels than a 1080p display and it requires extra processing power (and therefore , more battery) to render those extra pixels. OEMs sometimes include a 1080p mode on a 1440p display to help cut back on the processing power and save battery.


Displays use more battery than any other phone component.Brightness is another significant power draw. This is also a matter of simple math. The brighter something is, the more power it requires. It’s not as noticeable if you go from 50% to 40% brightness. You’ll almost certainly see a difference when going between 80% to 20%, though.


Finally, the display’s refresh rate matters a lot. The refresh rate represents the number of times a screen refreshes every second and is measured in hertz (Hz). Newer phones have 90Hz and 120Hz displays which refresh 50%-100% more frequently than regular 60Hz displays.

That requires a whole bunch of extra processing power and puts further strain on your phone’s battery. Modern phones have adaptive refresh rates to help combat the battery drain, dropping down to as low as 1Hz when viewing static content.
Displays eat up more battery than any other individual component of a device because it is the main way we interact with a phone. This is why most battery-saving tricks revolve around display tweaks. However, lowering your brightness a few percentage points does virtually nothing and the resolution only matters if you have lots of screen-on time. Finally, using dark themes on AMOLED displays doesn’t work as well as most think it does.


ConnectionsSamsung Galaxy S21 Ultra 5G speed testConnections have a massive impact on battery life. The most common connections are your cell phone signal, data, Bluetooth, Wi-Fi, and location services. Connections drain the battery in a few different ways and the first one is fairly obvious.
If you enable these connections and don’t use them, they draw unnecessary power over the course of the day. Hardware and software optimizations have minimized this drain and it’s barely an inconvenience these days. It still drains the battery, but not nearly as much as it used to.


Additionally, a weak signal can greatly increase battery drain. It’s also a very difficult problem to fix. Your device regularly checks for signal strength. When the reception is bad, the phone checks more frequently, and this constant checking drains the battery. Usually, this only happens in certain types of buildings and in bad reception areas, but if you live (or work) in one of those places, it can be a constant and nearly unsolvable problem.


Every time your phone connects to something, it costs you battery life.Finally, actually using these connections drains your battery. If you go online and spend five minutes downloading a file, that’s five whole minutes your phone is actively using its networking hardware. The same is true of voice calls as your phone engages its radio for the entire length of the call.


A lot of people recommend using airplane mode to switch off all connections when not using your phone. To be honest, it doesn’t save that much battery and it ends up being invasive and annoying. We recommend staying connected to Wi-Fi while at home (or work). Additionally, the Google Play Store, Google Photos, Amazon Photos, and others all have settings that will postpone backups or updates until you’re connected to a charger. You should definitely check and see what can be put off until your phone is safely charging.

For regular users, the first thing that matters for the chipset is its generation. Every year chips get smaller, faster, and more energy-efficient. The Snapdragon 855 was faster and more energy-efficient than the Snapdragon 845, and the latest Qualcomm chipset , the Snapdragon 8 Gen 2, continues the tradition. The same goes for HUAWEI’s Kirin SoCs, Samsung’s Exynos chips, and MediaTek’s silicon. This is a rather complex topic, but the super basic explanation is that newer chipsets can do the same work as older chipsets except faster, with less energy consumption, and with less heat. All of those things affectbattery life.