Smartphone Buyer’s Guide: Battery Size Is Not Everything
November 14, 2018 Andrew Cheng

One of the most important features of any device is battery life, and it’s a pain point for most folks. Chances are, you’ve brought your power bank out with your phone before because you’re running out of battery. This is especially true if your device is a few years old.

With that in mind, most consumers looking to get a new phone will want a device with a large battery capacity. However, a large battery does not equal to long battery life, and vice versa. There are a number of other factors to consider, including display, chipset, and most importantly, software optimisation.

Let’s talk about software first, which I’d argue affects battery life the most – after battery capacity, of course. The best example here is iOS versus Android. The thing is, iPhones typically have tiny batteries in comparison to their Android counterparts. Take the new iPhone XS Max: it only has a 3,174mAh battery. That’s much smaller than the battery capacity of most Android flagships, which can go up to 4,200mAh.

That being said, iPhones still have very good battery life; it’s actually quite amazing how long they can last despite having such “small” battery capacities. Imagine if Apple had put in even larger batteries into their iPhones – it may even outlast most Android devices.

So how is this possible? Software optimisation. In comparison to the fragmented nature of the Android platform, the closed ecosystem of iOS makes it much easier for Apple to optimise its mobile operating system. When it comes to software optimisation, there’s no denying the fact that iOS is superior to Android.

The next most crucial factor that affects battery life is a device’s chipset. Depending on the core configuration and size of the processor, it can impact battery life quite a bit. There are typically two types of cores in a chipset: lower-clocked, power-efficient cores, and high performance cores with faster clock speeds. How a particular chip switches between these two kinds of cores will determine how much power it draws.

Size of the chipset is equally important too. Currently, there are mostly 10nm processors in the market, which include the Qualcomm Snapdragon 845 and Samsung’s Exynos 9810 SoC. More recently, however, smaller 7nm chipsets are being introduced – the Huawei Kirin 980 and Apple’s A12 Bionic processors are built on 7nm processes.

It’s a simple rule of thumb: the smaller the chip is, the more power-efficient it is. Moving forward, expect the latest processors powering the next generation of phones to be smaller in size. 7nm – or even 8nm – chipsets may make headlines next year.

Last but not least is display, one of the most power-hungry hardware. Obviously, larger screens will draw more power, and the same goes for higher resolution panels. Both the battery and GPU of a phone will need to power more pixels as the resolution increases.

Panel technology also affects how much power is drawn. Generally, OLED panels are more power-efficient, as each pixel is individually lit as and when it is necessary. Contrast this with LCD screens, which need some form of backlighting for illumination. This, in turn, draws more power than necessary.

On top of that, OLED displays are especially power-efficient when displaying blacks – the pixels are completely switched off in this case. This also means OLED panels have high contrast ratio, a desirable trait for any high quality display.

Battery size does give us an indication of how long a device can last on a single charge, but don’t take it as a final metric; battery life is not determined by battery capacity alone. Whenever you’re shopping for your next smartphone, keep this in mind.

Of course, if battery life is your main concern, it’s good to narrow down your choices to devices with larger battery capacities. Smartphones with batteries larger than 3,500mAh are generally alright, such as the Pocophone F1 and Huawei Mate 20 Pro.