Overcharging iPhones will damage it

Not just Galaxy - Why can iPhone batteries explode?

Stephan Wiesend

Some Apple fans may react with glee to Samsung's Note problems, but are iPhones completely safe? A look at batteries as a potential source of danger.

EnlargeThe Note's "overheating problems" resulted in some spectacular images.

Samsung apparently made several mistakes in the affair surrounding the Galaxy Note 7: According to a US testing authority, the battery simply does not fit into the device, which can lead to a compression and a subsequent short circuit. Now the replacement devices are apparently also affected, although they use a different battery. However, the incidents draw attention to the fact that modern batteries are not harmless. The increasingly cheaper energy storage devices are now being used in cars, e-bikes, gardening tools, headphones and the cheap little power bank that you just received as a promotional gift. Apple batteries are not indestructible either. Cupertino uses lithium-ion batteries in its Macbooks, iPads and iPhones, which in individual cases can also go up in flames - although not nearly as often as with Samsung's Note. The manufacturers of notebook batteries now seem to have the technology under control. Perhaps the expensive series of product recalls between 2006 and 2009 had a beneficial effect here. Immature batteries from Sony made it necessary to recall millions of devices from almost all notebook manufacturers, including Apple.

Apple devices can also burn out

Lithium-ion batteries can also “run through” in iPhones, a Reddit user recently reported on a very special unpacking experience: a friend had ordered an iPhone 7, but when he unpacked the package he found a completely burnt device. Obviously, the battery had self-destructed during transport, without the delivery service noticing, by the way. But there are also terrifying reports from users who were carrying their iPhone 6 in their pocket when it suddenly went up in flames. As I said, these are isolated cases. The specialty of the Samsung devices was that they were brand new, undamaged devices. Actually every battery has an integrated overvoltage, charging and overheating protection. And the battery almost always fails instead of burning. In addition, some incidents involving the iPhone could have involved devices with a spare battery.

EnlargeAn iPhone 7 received its device as it were "Burnt on Arrival".

What to do

As a smartphone user, you hardly have to pay attention to anything. Modern smartphone batteries have many protective functions, so if the battery overheats, the charging of the battery is stopped immediately. Problems with charging or the sudden bulging of the iPhone due to a defective battery should be recognized as a warning signal. Above all, however, you should avoid overheating the device and thus the battery. It is not without reason that the NYPD has an impressive series of images that show why a smartphone should never be charged under the pillow or the duvet. Obviously this has caused quite a few fires.

EnlargeCell phones should not be charged under the pillow.

And you should know that if you drop or get wet, the iPhone's battery can be damaged. Furthermore, when replacing a battery, it might be better not to use the E-Bay battery for 4.90 euros, but invest a little more. And after the replacement, you shouldn't forget the old battery somewhere, but dispose of it via the dealer or, for example, a GRS collection box.

What exactly happens when the battery explodes

As many know-it-alls have already stated, “explosion” is actually not entirely correct. In most cases it is a sudden heating or ignition, also called thermal runaway. This can happen with varying degrees of intensity, from a little smoke to a real explosion. The Samsung victims were mainly shocked by the completely surprising start of overheating - the smartphone was often neither plugged in nor was it particularly stressed. This "surprise effect" is probably due to the fact that physical damage can only trigger a fire some time later. The reason: In simplified terms, a battery consists of a cathode made of lithium and an anode, usually graphite. A separator separates these two elements. In the Samsung smartphone, however, the battery was apparently compressed due to insufficient dimensions. However, if the cathode and anode connect, a short circuit occurs. This is clearly demonstrated in countless YouTube videos, which can be found using the search term “lipo explosion”, for example. Two other possible causes are overheating and electrical faults such as deep discharge.

EnlargeYou can find some spectacular videos on the topic of smartphone batteries on YouTube.

Danger arises from the extreme heat of several hundred degrees, which can cause burns or an apartment fire. The toxic vapors that are created are also dangerous, but are evidently difficult to detect by fire alarms due to their special composition. A burning battery should also be extinguished with powder or sand, the FAA recommends extinguishing battery fires in aircraft with halon or water. The lithium in the battery, however, reacts strongly with water; at best, it helps in large quantities to cool the thermally broken battery. However, if you only use a few pieces of ice or cover the battery, this can actually intensify the fire - you shouldn't touch the device under any circumstances.

A battery pack smokes, a defective charger is fatal

Continuous batteries haven't killed anyone yet. So far, however, there are three known deaths of young users who, according to reports, died while charging their iPhone or iPad. In all cases, however, not a defective battery but a defective charging cable - for example because the iPhone fell into the bathtub and the user was electrocuted. In Germany, however, a fatal electric shock should be unlikely because a so-called FI switch is supposed to prevent this in newer apartments. However, you should still be careful when buying cheap power supplies or external batteries. It may not always have to be an expensive original Apple device, but at least a branded device from companies like Anker instead of the EUR 2 direct import from China.

E-bikes as a real problem

As impressive as a burning iPhone or Note may appear, devices such as e-bikes and drones pose a far greater danger. The battery of an e-bike has a charge of 500 Wh and can therefore cause far more damage than an iPhone battery with perhaps 6 Wh. Many e-bike buyers apparently still do not know that there are rules to be observed when storing and discharging .

EnlargeHere an e-bike caused a small apartment fire.

For example, batteries should only be half charged for longer periods of storage. Incorrectly stored batteries have already triggered several apartment fires, as a report by the SWR showed. Many users are not aware that a simple fall on an e-bike could trigger a battery fire days later. If the bike is not used for several months, for example in winter, a deep discharge could also trigger the burnout. The combination of high capacity and high physical stress is probably dangerous. So it is not surprising that burning batteries have also been known among drone users and model builders for years. Incidentally, self-made batteries from cheap components often cause problems.

EnlargeThe batteries of an e-bike store up to 500 Wh and are not without danger.

It is not without reason that high-capacity batteries are no longer transported by airlines and smaller replacement batteries are only allowed to be carried in hand luggage.


Devices with rechargeable batteries are becoming more and more widespread, but smartphone batteries are still relatively harmless. Especially with larger devices such as e-bikes or leaf blowers, however, you should absolutely observe a few rules when charging and using them. And when buying peripherals like chargers, we recommend paying attention to things like CE mark and quality.