Does fast charging kill your smartphone battery? What experts say

Fast charging has become an indispensable feature of modern smartphones, allowing them to replenish a charge in just a few minutes. However, many users are worried about whether it shortens battery life and leads to premature wear and tear. PCMag tells whether fast charging is really harmful to the battery and whether it is worth using it every day.
How smartphone batteries work
Smartphone batteries, like most lithium-ion batteries, consist of two layers - lithium-cobalt oxide and graphite. When lithium ions move from the graphite layer to the lithium-cobalt oxide layer through the electrolytic solution, electrons are released.
When the battery is charging, the ions move back in the opposite direction and accumulate, only to be released again when you turn on and use the device.
This process generates heat, which you may feel on the back of your smartphone after a long charge or heavy use. Overheating can damage the battery in the long run.
However, modern lithium-ion batteries have become more compact and efficient. They can withstand a greater number of charging cycles - from discharge to full charge and back again - before they begin to lose their capacity.
Why smartphone batteries lose capacity over time
With each charging cycle, your smartphone naturally wears out. One of the reasons is the electrolyte solution inside the battery. Over time, the salts contained in it can crystallize, forming solid deposits that interfere with the transfer of ions. The fewer ions that pass through the solution, the fewer electrons are released, which means that the battery will not be able to deliver as much energy as a new device.
This process is accelerated when the smartphone overheats, for example, when using fast charging when too much energy is delivered to the battery at once. But damage can also occur if your phone is left in a hot environment, such as on a car dashboard on a sunny day.
Another factor is overcharging. If the battery receives more energy than it can safely accept, too many lithium ions are pulled out of its structure, which leads to irreversible changes. And it is impossible to get the lithium back.
"The atomic structure of the material literally collapses if you remove all the lithium... It's like removing the pillars from under the floor of a building," explained Kent Griffith, an energy storage researcher at the University of Cambridge.
If the battery is properly maintained, the degradation process will slow down. But ultimately, any lithium-ion battery will experience this, no matter how carefully it is used. In modern smartphones, you can check the battery status in the device settings.
Why phone batteries lose charging capacity over time (photo: Samsung)
How smartphones reduce battery wear and tear
In the early days of fast charging, batteries got very hot during charging. Back then, smartphones didn't have effective systems for dissipating heat from the battery, which made them more likely to overheat. Modern devices are better at ventilation and no longer face this problem.
Today, they use advanced technologies to manage heat and control power delivery during charging. For example, modern smartphones have heat dissipation plates, thermal protection layers, and even cooling tubes that remove heat from the battery.
In addition, most phones automatically cut off power when the battery is fully charged, even if the device remains plugged in. Some smartphones also adapt the charging process to your schedule - for example, by keeping the charge level at a safe level and bringing it to 100% only an hour before you wake up.
Multi-stage charging allows for accelerated charging in stages. When the battery is at its lowest state of charge, more power is delivered to the battery because it is able to absorb energy faster in this state. However, as you approach 100%, the charging speed slows down. In other words, your phone is not charged at full power (e.g. 80W) throughout the entire process. This is why modern smartphones can be safely charged at night without the risk of overheating or fire.
Some gaming smartphones are equipped with built-in cooling fans to keep battery temperatures low. Companies such as Xiaomi use the technology of dividing the battery into several cells, which reduces the load on each of them and achieves high charging speeds without, as the manufacturers claim, negatively affecting the battery.
Apple's iPhone has a battery optimization setting (photo: Apple)
Should you use fast charging
Is fast charging really bad for your smartphone? Yes and no. It can have a negative impact on the battery, especially if it is used too often and for a long time at high power. However, modern devices are equipped with intelligent charging management systems that minimize potential damage.
However, according to popular tech blogger Marques Brownlee, many of these technologies are too new, and there is not yet enough long-term data to prove their effectiveness. Therefore, the question remains open, and it is not worth relying entirely on manufacturers' statements.
You may be interested:
- 10 misconceptions about iPhone charging that people still believe
- Key pros, cons and tips on how to use wireless charging properly