More doesn't mean longer: how does battery capacity affect battery life?

Autonomous operation throughout the day is the main requirement of any user when buying a new smartphone. It would seem that it is quite easy to refer to the specifications, look at the number of mAh (mAh or milliampere-hour) and draw conclusions. But this can sometimes lead to some difficulties: we wonder at the short battery life of a seemingly huge 4,000 mAh battery, or wonder how long a tiny battery can last inside phones like the iPhone SE.

The phone's mAh rating is a rather meaningless statistic when viewed separately. Battery life is actually a very complex thing, depending on a wide range of hardware and software variables. Consider why you should not trust the mAh numbers as the only indicator of the battery life of a smartphone.

What does mAh mean?The abbreviation mAh, indicated in the battery specifications, means milliampere-hour. It is a unit of electrical charge that is equal to the supply of one milliampere of current continuously for one hour. So a 1 mAh battery can provide 1 mA current for an hour, and a 1000 mAh battery can provide 1 mA current for 1000 hours.

However, a 1000 mAh battery providing 2 mAh current will only last 500 hours. It is clear that smartphones do not work for hundreds or thousands of hours, because they consume much more than 1 mA of current from the battery. The more current consumed by your phone, the shorter the battery life.

All other things being equal, a phone with a larger battery capacity will last longer than a smaller one. However, this is rarely observed, as the phone's filling and therefore power consumption vary widely. Model number 1 can consume 10, 20, or even 30% more current than model number 2.

The uniqueness of each smartphone's hardware and software means that no two devices are the same. That's why just knowing the battery capacity in mAh won't give you really useful information about the expected battery life.

MACH: Numbers or resultsbefore delving into the answers to the "why" questions, let's run some tests. We ran a number of phones with different specifications and using the Speed Test G test and recorded how long it took to fully discharge the battery.

The results are arranged in ascending order of battery capacity. As you can see, there is no clear and obvious trend in them. One would expect that the battery life would roughly increase with increasing capacity, but this is not the case.While smartphones with giant 5,000 and 6,000 mAh batteries were supposed to provide the longest battery life under stress test conditions, the Google Pixel 3a XL actually won with 3,700 mAh. The difference of just a few minutes between the 3700 mAh in the Pixel 4 XL and the Asus Zenfone with its 6 5000 mAh battery, only says that the battery capacity alone is not a guarantee of a long service life.

Perhaps the most striking trend: most phones fall into the 3.5-4 hour battery life span. It seems that these numbers are what manufacturers are aiming for - the Google Pixel 4 at 2800 mAh, the Galaxy S20 at 4000 mAh (Exynos model) and the 4510 mAh OnePlus 8 Pro-all within minutes of each other. Obviously, different hardware specifications and software functions use the battery differently.

It all depends on the "filling" The battery powers all the equipment of your smartphone, from the processor to the screen. Obviously, different hardware uses different amounts of power. For example, low-and mid-level processors consume less power than their flagship counterparts.

In general, higher performance requires more power. That's why so often budget phones have longer battery life than premium phones with the same battery capacity.

But even flagships, as you can see, can have very different levels of power consumption. Look at the situation with the Samsung S20 based on the Exynos chipset and Snapdragon. Manufacturers may underestimate the speed or, conversely, overclock the chipsets to achieve the preferred performance.

There are some good examples of how additional hardware can drain the battery faster. The Google Pixel 4 and its Soli radar system are a prime example of having a feature that will speed up the discharge.

Having a time-of-flight camera with its focus system, more powerful stereo speakers, or a 4K display also affects battery life. Even something quite small, like charging the S Pen in the latest Galaxy Note phones, affects the battery life. Yes, these features make the phones unique, but they also have a price.

The trend towards increasing display refresh rates also plays a big role in why modern phones consume so much power. This is the reason why the Samsung Galaxy S20 series phones support 60 Hz natively, despite having 120 Hz support. The Pixel 4's 90 Hz mode lowers the display brightness in an attempt to extend battery life. The reason is that the faster the display content is updated, the more power it consumes.

Want some more examples? Did you know that the 4300 mAh OnePlus 8 with a 90Hz screen provides longer battery life than the 120-hertz OnePlus 8 Pro with a 4510 mAh battery? Otherwise, the two phones have virtually identical specs - and this highlights just how much of an impact the refresh rate can have on battery life.

Keep in mind that battery life is not just a matter of hardware stuffing. Smartphone software can also affect battery life by unloading background apps from memory to reduce CPU load. Huawei's EMUI shell is known to be more aggressive in this regard than the Samsung UI One.

5G power consumption Another recent trend complicating the battery situation is 5G support. Modems and radio components for 5G consume more power than similar ones for 4G networks, which means that your battery will not last long in the case of a 5G connection. The situation is complicated by the fact that different 5G modems and chipsets consume different power levels.Mid-range chipsets with built-in 5G modems, such as the Exynos 980 and Snapdragon 765G, should consume slightly less power than the external premium modems used in flagship smartphones. This may be partly why the LG Velvet and rumored Google Pixel 5 models are abandoning Qualcomm's power-hungry flagship chipset, the Snapdragon 865.

The move to 5G hardware has certainly increased the need for higher-capacity batteries. However, whether this is an important parameter when buying depends on whether you really need support for 5G networks that are not yet widespread.

If you are currently working with 4G, which is most likely, the power consumption of the smartphone components will not be as high, and the battery life will be slightly longer.According to Redmi CEO Lu Weibing, switching from 4G to 5G usually requires at least 20% more power.

The question of balance is the key conclusion from all that has been said: it is not so easy to create a smartphone with a long battery life, how to build the maximum possible battery into it. Manufacturers must take into account the cost, the amount of free space in the case and the equipment that they are going to use. The more functionality there is in the phone, the more difficult it is to balance it all. Most manufacturers try to achieve a balance in the necessary equipment and battery capacity, which will help you use your smartphone throughout the day.

The stress test did not reveal a direct relationship between capacity and battery life, because there is no such relationship. Larger batteries obviously provide more power, but the choice of equipment made by manufacturers has no less impact on the actual results of the battery.

Mid-range smartphones with less energy-intensive technologies, such as the Pixel 3a, have smaller batteries, while working all day. In the premium segment, manufacturers use larger capacity batteries to support more energy-intensive technologies, such as 5G, high refresh rate displays, or additional performance in games.

Of course, the way you use your phone also has a big impact on battery life. Fans of social networks and surfing the Internet end up with much lower battery consumption than mobile gamers.