A phone battery loses capacity over time, that cannot be avoided. But how fast it wears out depends a lot on heat and on how it is charged. Here is what really damages it, what is a myth, and how to tell when to replace it.
How a lithium-ion battery wears out
Phones use lithium-ion batteries. They wear out in two ways: with charge cycles (one full charge from 0 to 100%, or twice 50%) and with time, especially when they stay hot or full for long. After a few hundred cycles, a battery usually keeps around 80% of its original capacity.
Heat, the main enemy
In a Moroccan summer, this is the factor that matters most. Avoid leaving the phone in the sun, on the car dashboard or under a pillow while charging. Gaming or filming for long while charging heats it from both sides at once. A thick case that holds heat can come off during long charges.
Stay between 20 and 80% when you can
A battery wears faster when it sits at 100% or often drops to 0%. No need to obsess: topping up during the day instead of waiting for the phone to die, and not leaving it plugged in at 100% in the sun, already helps.
Most recent phones have a setting for this: optimised or adaptive charging, which waits before going past 80% overnight, or a charge limit at 80 or 85%. It is in the battery settings.
What is a myth
- You should fully drain the battery now and then. That was true for old nickel batteries. For lithium-ion, full discharges wear it out.
- Charging overnight damages the battery. The phone stops charging when full, and optimised charging reduces time spent at 100%.
- You should close every app. The system manages background apps. Reopening them all the time can use more power.
Charger and cable
An unbranded, uncertified charger may not regulate voltage properly and can overheat. Choose a charger that clearly states its power and fast-charging standard (USB Power Delivery or Quick Charge, depending on the phone). Fast charging does not wear the battery noticeably as long as the phone does not get too hot. A damaged cable, with exposed wires or a bent plug, should be replaced.
In the car, a good car charger avoids cut-outs and voltage spikes when the engine starts.
Using less power day to day
- Auto brightness and a dark background (on OLED screens) save a lot.
- Location set to “while using” rather than “always” for apps that do not need it.
- Power saving mode when you know you cannot charge before the evening.
- In areas with weak coverage, the phone keeps searching for signal and drains fast. Airplane mode or Wi-Fi only helps.
When to replace the battery
The settings often show battery health as a percentage of original capacity. Below 80%, or if the phone shuts down at 20 or 30%, it is time to replace it. A swelling battery (screen lifting, case bulging) must be replaced straight away and no longer charged.
On the go
For long days, a power bank saves the phone from dropping to 0%. The guide choosing a power bank explains how to read its real capacity and what is allowed on a plane.
If the phone stays in a drawer
A phone that will not be used for weeks should be stored charged to about 50%, switched off, in a cool place. Stored empty, the battery can drop too low and stop taking a charge.
