Is A Hot Battery Charger Normal and Can It Damage Phone Battery

Carrie Tsai - Neway
10 min readDec 24, 2020

By Carrie Tsai, Last Updated: December 24, 2020

“Ouch! Every time I use my battery charger to charge my phone, it gets hot to the touch when it’s plugged in for a while. This is often accompanied by the heating up of my phone. Why does this happen? Is this normal? Can this cause damage to the phone battery?”

It isn’t surprising if you also encounter this problem. Instead, you’re not alone. In fact, when charging the battery of mobile phones, tablets, and even laptops, battery chargers especially those for Li-Ion batteries will inevitably heat up and even make the charged devices get hot. When facing this situation, many people will be afraid if it can cause burning or damage to their devices.

Is it normal for a battery charger to get hot during the charge? Can it cause any damage to the phone battery? Well, take it easy. In order to better explore the questions, we’ll first discuss the reason why your battery charger and even your phone warm up during the charge. Then the article will keep exploring the main questions and will also give you some tips on how to reduce the damage to your phone battery. Keep reading.

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Why Does Your Battery Charger Heat up When Charging Your Phone

Before discussing why a battery charger heats up when charging a mobile phone, having an understanding of how a charger works are helpful.

Just like a battery that gives you the power to operate your phone or any other mobile device, a battery charger gives the battery power to make it work regularly. Essentially, a battery charger works by transmitting electric current to batteries for a period of time in the hope that the cells (power-generating compartments) inside of the batteries can maintain the energy passing through them.

More specifically, reversed to the battery’s working which converts chemical energy stored in it to electrical power to give the power to devices, a battery charger carries electric current through the battery by converting the electric power to the chemical energy which is used to regenerate the run-out electrolyte inside of a battery.

* The Battery Charger Isn’t Compatible

That being said, a battery charger charges a mobile phone by transmitting an electric current for a period of time. But why does the charger get hot during the charging process?

* Using Cheap Third-party Battery Chargers

Well, the vast majority of causes rest in a process occurring inside of a charger which is specific to charging — voltage and current conversion. This kind of process refers to the conversion of low voltage to high and the conversion of alternating current (AC) to direct current (DC).

Due to the fact that most mobile phones and other electronic devices only support low-voltage direct current which can ensure consumer safety while the normal current from the socket for home use is high-voltage alternating current, there is a need for voltage and current conversion.

* Placing the Charger and Charged Device on Heat Traps

However, the conversion process certainly causes some energy losses since the conversion efficiency cannot up to 100 percent. Generally, when converting the alternating current to direct current, a normal battery charger is capable of transmitting around 70% of electric current, while the other 30% is converted to heat energy and is diffused. This is what causes the heating up of your battery charger when it’s charging your phone.

Is It Normal for A Battery Charger to Get Hot When Charging Your Phone

* Charged-Device Malfunction

Given that the conversion from high-voltage AC to low-voltage DC during the charge isn’t 100% efficient, it’s normal for phone battery chargers to have standard warming-up when charging mobile phones.

Nevertheless, not all heating cases are normal and are of no concern. In addition to the conversion efficiency, there are still a large number of causes for heating up the battery charger during the phone charge. And it’s worth noting that heating has to be moderate. Overheating which is nearer to reach burning temperatures point has a much higher risk in burning.

That said, if you have your battery charger warm up while charging your phone, this could be a sign of something serious rather than a normal phenomenon. Hence, every time you find that your battery charger gets hot, you should try to figure out the cause in order to lower the risk of burning of your charger and your phone.

In addition to the normal phenomenon, here are some of the major reasons why your battery charger gets hot as you use it for charging:

Even though you successfully connect a charger whose terminal plug can match the port from your phone, this doesn’t necessarily mean that the charger could be compatible with your device. Charger incompatible with your device may not be used to charge your device as it may cause heating-up on either the charger or the connected device.

Hence, if your battery charger always gets very hot during a charge, check to see if it’s compatible with your device. If it isn’t, replace it with a new one that is well compatible.

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If your battery charger is at a very high temperature every time you use it to charge your phone, the problem could be that the charger is cheaply made and comes with no strict safety precautions. Some third-party battery chargers at a very cheap price may not go through a strict electrical evaluation and may be made without proper safety precautions, which makes them prone to potential risk.

Thus, it’s advisable for you to always use an original battery charger or at least a charger that is certified and comes with proper safety precautions. For example, if you’re using an iPhone, you’d better charge it by using Apple’s original charger or choosing to use a charger which is certified by Apple MFi.

Placing your battery charger and your phone on a cushioned surface or on the bed can also cause the heating-up of your charger and your phone. This is because a cushioned surface essentially gathers the heat by restricting airflow on the charger and the phone, making the temperature increase. Under this circumstance, a proper fix is to immediately put your charger and your phone onto a flat place where air can flow freely.

A hot battery charger or charged phone can be also led by the electrical malfunction of your phone. This is because electrical malfunction can easily cause a short circuit which can definitely heat up the phone itself and the connected battery charger or can even easily cause overheating and burning accidents.

Can A Hot Battery Charger Cause Damage to Phone Battery

Generally speaking, if a battery charger gets hot during a phone charger, the heat can further be transferred along the data cable to the phone, making the cable and the phone warm up. However, can the heat from a battery charger cause damage to the phone battery?

Well, this depends on the level of heat. Normally, if the battery charger has standard moderate warming-up when charging a mobile phone or any other electronic device (caused by the normal energy diffusion from voltage conversion), it should have little effect on the phone battery. Otherwise, an abnormal increase in temperature of a battery charger during a charge can cause permanent damage to the phone battery.

This is because, on the one hand, batteries of mobile phones or other electronic devices contain fluids and work through chemical reactions. When the heat is transferred from a battery charger along a charging cable to a device, the fluid inside of the device battery evaporates through chemical reactions, which causes damage to the internal structure of the battery. The improper internal structure makes the battery charge much faster, leading to electrolytes loss and in turn decreasing long-term battery life.

On the other hand, when the battery charger heats up, the heat can be applied to the connected phone, making the electrons within the battery excited. Excited electrons can push the chemical reactions inside of the battery to occur faster, which can overtime reduce long-term battery life.

How to Reduce Battery Damage Caused by Heat During A Charge

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In fact, when charging a mobile phone or any other electronic device, there will be some heat inevitably diffusing from either a battery charger or the connected device. That being said, heating-up is unavoidable.

However, in addition to the standard warming-up of the battery charger which doesn’t cause damage to the phone battery, other causes of making battery temperature increase can mess up battery life permanently. Hence, every time you charge your phone, you should try to reduce the heat produced in order to reduce damage to your phone battery. Let’s run down some proper tips which are useful for reducing battery damage during a charge.

Turn off Phone Screen and Turn on Airplane Mode

Using your phone while it’s charging can increase the overall power of your phone, making your phone get hot and thus causing damage to the battery life of your phone battery. Hence, don’t use your phone during the charge. Turn off your phone screen or whack Airplane Mode on when you’re charging your phone.

Turning on Airplane Mode stops your phone from seeking out and using networks but still allows you to use your phone, which can reduce heat from your phone and in turn reduce damage to the phone battery. To turn Airplane Mode on, simply go to Settings and enable it.

Don’t Overcharge Your Battery

Overcharging your phone can also cause damage to the phone battery and more seriously to your phone itself. This is because, on the one hand, charging a battery beyond its capacity can build up too much internal heat to the battery, which can degrade battery life over time. On the other hand, overcharging a phone can make the battery become overheat, increasing the risk of phone burning.

Hence, don’t overcharge your battery. Once your phone is fully charged, charging should stop immediately.

Do Not Use Low-quality Power Bank

The majority of mobile phones require a battery charger or a power bank to distribute an output voltage of around 5V. However, many power banks especially those of low quality provide a lower or higher voltage than what’s needed to charge your phone.

Matching a lower or higher voltage when charging your phone can cause serious damage to the battery life of your phone. Therefore, if you need to use a power bank instead of a wall battery charger to charge your phone, you should choose one which is of high quality and can provide the voltage that’s required to charge your mobile phone.

Use Wireless Charger As Little As Possible

Wireless charger, as a new kind of charging technology, is indeed cable-free and brings users a lot of conveniences. However, it can also be the cause of damage to the phone battery lifespan.

This is because wireless charging produces greater power loss. The power can be further converted into heat gathering on the place of the charging board where the mobile phone is placed, which can damage the battery over time. Thus, use a wireless charger as little as possible.

Try to Avoid Charging Your Phone Via the USB Port from Your PC

Normally, don’t charge your phone by connecting it to your PC via the USB port on your PC. This is because the charging speed of the USB port from your PC is much lower than that of the battery charger. Lower charging speed requires a much longer charging time, which can expose your phone to heat for a longer period of time and thus cause damage to the battery of your phone.

Charge Your Phone in a Well-ventilated Environment

Every time you charge your mobile phone, you should keep it and the battery charger in a well-ventilated environment. This can help dissipate heat to avoid extreme temperature and to reduce damage to the battery of your mobile phone.


Now everything is clear! Normally, due to the fact that the voltage and current conversion isn’t 100% efficient, it’s normal for a battery charger to have standard heating-up when charging a mobile phone.

However, a hot battery charger isn’t always of no concern. For heating cases caused by an incompatible or cheaply made charger, phone malfunction or improper position, the hot battery charger can cause damage to the phone battery. Since the heat isn’t avoidable during a charge, you should try to reduce the heat produced from both your charger and your phone to reduce the damage to your phone battery.



Carrie Tsai - Neway

Carrie Tsai is part of team Neway and is always active to share her ideas of Neway. She enthusiastically dives each day into the depths of the mobile industry.