Does fast charging hurt your phone battery?

The fast charging function is, without a doubt, one of the most popular trend features of modern smartphones. That’s understandable, as it’s more than practical during the day when you don’t have to wait for an eternity to fully charge your phone.

The whole thing has now gone so far that there is a real competition between manufacturers to see who can provide the best and most powerful charging technology. At last year’s MWC, Xiaomi demonstrated its impressive charging technology, which pumped a Redmi mobile phone with 4,300 mAh to a full charge with a whopping 300 watts in just five minutes.

As fascinating as those figures above are, many smartphone users are becoming increasingly concerned. After all, can this be healthy for the mobile phone battery? A legitimate question, which we address in this article. Find out what fast charging does to your mobile phone and whether or not it can actually ruin the battery.

Further reading: The best USB-C cables for charging and transferring data

What happens during the charging process

All modern smartphones use either lithium-ion batteries or lithium-polymer batteries (LiPo batteries for short). However, cell chemistry is the same for both. There is a negative electrode (cathode), a positive electrode (anode), and electrolytes. The energy that powers a mobile phone is generated when the negative lithium ions flow through the electrolytes to the positive side. When the battery is empty, this flow stops. During the charging process, the lithium ions are moved back to the negative side so that the cycle can start again.

The charging process is not exclusively linear because batteries function like a kind of sponge. They absorb most of the energy when they are empty and absorb less when they are almost full. So the closer to saturation, the less efficient the charge and the flatter the charging curve. The charging voltage, on the other hand, starts at maximum power and then drops relatively quickly.

Simplified illustration of a mobile phone charging process: The charging efficiency decreases from around half the battery level.

Mobile phone batteries degrade

Whether fast charging or not, all batteries wear out over time. This is because the flow of lithium ions always releases some heat, to which the chemical processes react very sensitively. For this reason, you should not plug in your mobile phone when the battery is still relatively full, as inefficient charging releases even more heat.

Note: On iPhones, this natural wear and tear can even be viewed. Under Settings > Battery > Battery Status & Charging Process, you will find a percentage indication of the maximum battery capacity that is still available.

Heat is therefore the main reason why batteries degrade. Many users see this problem with the “fast charging function,” because the more current flows into the battery, the more excess heat is generated. Acute overheating can even cause the electrolytes to crystallize and the ion current between the electrodes to fail completely.

But –and this is the crux of the matter–manufacturers know this, of course. That is why there are a number of important precautions to prevent more heat than normal being generated during fast charging.

Fast charging requires new technologies

In recent years, various fast charging standards have been developed to increase the transmission performance of power supply units. Qualcomm’s Quick Charge protocol, for example, is widely used. Version 5 enables charging from 0 to 50 percent in just 5 minutes at 100+ watts.

OnePlus’ WarpCharge technology manages 65 watts. Another standard is VOOC Flash Charge from Oppo, for example, which has also replaced the Warp Charge technology at OnePlus since the two companies became part of the same group. The OnePlus 10T mentioned above, for example, comes with a 150 watt SUPERVOOC power supply. Other standards include USB Power Delivery, Adaptive Charge (Samsung) and TurboPower (Motorola).

There are now several ways and options for protecting mobile phone batteries. The most common solutions include…

Power supply unit with integrated power management

Parallel charging

Additional cooling hardware

Many smartphones with a fast-charging function are supplied with power supply units that have integrated circuits. These ensure that the heat energy can escape before it gets close to the mobile phone. The disadvantage of this solution is that the adapters are often larger than usual.

Another option is parallel charging. The idea is simple. Instead of sending the entire current into a single battery cell, it is split into two parallel cells. The two solutions are now frequently combined for the best possible charging performance. The downside of this charging technology is a slightly lower overall capacity. This is simply because the volume of two battery cells, including the housing and hardware, takes up more space.

With parallel charging, the power is divided between several battery cells.©Xiaomi

Cooling hardware is always a solution for regulating heat development. The better the cooling system, the more power can flow into the device without overheating it. There are plenty of options: heat shields, vapor chambers, even entire fans (especially on gaming smartphones) are used to protect the batteries from excessive temperatures.

Which brings us back to the initial question. Does fast charging ruin mobile phone batteries or not? Do the solutions listed work? How quickly does a battery have to degrade to be considered “ruined”?

There are even official industry standards for the latter: Xiaomi guarantees that 80 percent of the original battery capacity is still available after 800 full charging cycles with its 11T Pro (with 120 watt fast charging). Apple promises a capacity of 80 per cent after 500 charging cycles. And then there is Oppo. At the beginning of February 2023, the Chinese manufacturer presented two new fast charging standards: 150W SuperVOOC and 240W SuperVOOC technology with 80 percent battery capacity after no less than 1,600 charging cycles. We are excited to see what breakthroughs await us this year.

Does fast charging ruin the mobile phone battery or not?

Without long-term studies, it’s not possible to answer this question definitively, but so far everything points to the fact that fast charging does not accelerate the normal wear and tear of a battery.




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However, it’s also a fact that fast charging generates more heat due to the higher wattage, from which the phone must be protected. To this end, manufacturers use various measures aimed at improving energy management–be it through optimized power supply units, parallel charging or smart hardware, and sensors to regulate temperature fluctuations.

The users themselves actually have the greatest influence on battery life. Here are some quick tips on how to keep your mobile phone battery fit for longer:

Always charge with a cable if possible, even if your phone offers inductive charging.

Avoid complete discharges. The optimum battery level is between 20 and 80 percent.

Do not charge your battery if it is still relatively full (over 60 percent).

Avoid extreme temperature fluctuations, whether heat or cold.

Always use the charging accessories supplied by the manufacturer (plug adapter, charging cable).

Do not charge your mobile phone when performance-intensive apps or games are running.

Do not leave your mobile phone plugged in for longer than necessary when the battery is fully charged.

This article was translated from German to English and originally appeared on pcwelt.de.

Smartphones