Smartphone battery: 7 habits that make it last longer

The lithium-ion batteries in smartphones wear out with use. After a few hundred full charge cycles some of the original capacity is gone for good. How much, and after how many cycles, depends on the model, and manufacturers state a figure for each phone (often something like 80 percent of capacity after 500 or 1000 cycles), which you will find written in your own phone’s specifications. The process doesn’t stop, but you can slow it down a lot. Here is what really matters.

1. Avoid the extremes: neither 0 nor 100 percent

The greatest stress on a lithium cell comes when it is completely empty or completely full. Keeping the level between 20 and 80 percent as much as possible reduces wear. Both iPhones and recent Android phones have an option to limit charging to 80 percent (on iPhone under Settings > Battery > Charging, where you will find the slider that stops the charge at 80 percent; on many Android phones under Battery > Battery protection). If you don’t need the full range every day, turn it on.

2. Heat is enemy number one

Heat is what shortens a lithium battery’s life most. The hotter it works, the faster it ages, and temperature damage is not recovered when it cools down again. So no phone in the sun on the dashboard, and no charging under a pillow. And if it gets hot during fast charging or while you’re gaming, take the case off.

3. Fast charging is fine, but not always

65 W or 120 W chargers are convenient, but they generate more heat. For overnight charging use the standard charger, or “optimised charging”, which learns your schedule and finishes charging shortly before you wake up.

4. There is no need to “calibrate” the battery

The advice to fully drain the phone once a month dates back to the nickel batteries of twenty years ago. With lithium it achieves nothing. And leaving the battery flat for days genuinely does harm it, so it’s a habit to drop and leave at that.

5. Check who is draining it

Under Settings > Battery you’ll find the list of the hungriest apps. If an app you rarely use sits at the top, restrict its background activity or uninstall it.

6. Wireless charging in moderation

It is convenient but less efficient, because part of the energy is lost as heat. Use it when it suits you, keeping the cable as your main method.

7. Use trustworthy chargers and cables

It does not have to be the original. But it should be from a recognisable brand, with the specifications printed on it and a seller you can go back to. If the charger or cable carries USB-IF certification (the consortium that defines the USB standard), that is a further good sign. The CE mark is a different thing, and the confusion here is common: it declares conformity with the applicable European rules, it is required to sell in Europe, and it is neither a quality certification for the charger nor the equivalent of USB-IF. The anonymous few-euro products, often with no traceable seller, are where the problems concentrate.

When it’s time to replace it

Below 80 percent of remaining capacity the phone lasts noticeably less between charges, and that is the threshold manufacturers use for warranty purposes. The serious symptoms, though, are different ones, and they can arrive earlier or later. Sudden shutdowns while the charge is still high, or, on iPhone, the slowdown the system applies after the first abnormal shutdown to prevent further ones.

A replacement costs a few tens of euros at an independent repair shop and considerably more through official service on recent models. Get a quote for your own phone, because the figure varies a lot from model to model.