Modern smartphones are equipped with very large capacity batteries: 5000mAh is common, although 2000mAh was the norm some ten years ago. In order not to sit with such smartphones near the outlet for many hours, fast charging was invented: that is, charging using increased current and voltage.
Enhanced means more compared to the standard 2 amps at 5 volts, although recently such parameters were also considered “fast” compared to 1A – and according to the USB specification, 500 mA is generally enough, and on old laptops and desktops it was.
The power at 5V and 2A is 10 W (5×2=10), in fact, it is slightly less due to losses. But modern smartphones are equipped with 50-watt, 66-watt, and 80-watt adapters, and some models even set records: 150 or even 240 watts. And here the question arises: isn’t such fast charging harmful to the battery? How quickly will it fail? What if manufacturers specifically make more and more powerful charging systems specifically so that we can buy a new smartphone faster?
A lithium-ion battery has two layers: graphite and lithium-cobalt. During the operation of the battery, ions move from the graphite layer to the lithium-cobalt layer through the electrolyte solution.
When charging the battery, the ions move in the opposite direction into the graphite layer. Battery wear occurs due to the fact that the salts contained in the electrolyte crystallize and become solid, and ions no longer pass through these areas. The fewer ions that can move back and forth, the smaller the effective capacity of the battery.
The crystallization process is irreversible, and it noticeably accelerates with increasing temperature. And the temperature of the battery can rise for various reasons. For example, you left your phone in the sun. Or… connected it to fast charging, during which the battery heats up.
That is, it turns out that fast charging is still harmful. Yes and no. The first smartphones with fast chargers really warmed up significantly in the process. But modern models have effective heat dissipation – cooling systems “serve” not only the processor but also the battery – up to the evaporation chambers.
At the same time, charge controllers monitor the temperature of the battery and prevent it from charging too fast and too “hot”.
Accordingly, the harm or harmlessness of fast charging depends not on the supplied power, but on the implementation of the cooling system in a specific smartphone. It is obvious that the flagships of A-brands are doing well in this regard, but budget models of third-tier Chinese manufacturers will most likely save on good heat dissipation.
Although the smartphone will charge quickly and even then it will not explode, due to constant overheating, its life will be short-lived and you will have to change the battery for a new one quite soon – you will feel the effect of “aging” after a year.
Overheating of the battery causes it to swell due to the release of oxygen. Such a battery can still be used for its intended purpose but for a very short time. Low-quality batteries deflate the fastest.
And, of course, no cooling system will cope if it’s hot around. So try to use fast charging in cool places. And yes, putting the device near an open window in winter is a good idea. And in the summer – under the air conditioner. So the battery will really last longer.