The Samsung Galaxy Note 7 became infamous shortly after its launch in August this year when reports emerged of phones overheating, setting on fire, and even exploding.
Even though there were only 35 incidents out of more than a million phones sold, Samsung issued a full recall-and-replace order… until the replacements started exploding, too. Samsung has since issued a full recall on all remaining Galaxy Note 7 devices and even suspended production.
But the Galaxy Note 7 is not the first device to be recalled for this reason, and it probably won’t be the last. In 2011, Apple recalled a batch of its first-generation iPod Nano devices. In 2007, Nokia recalled 46 million phone batteries, and there have been more than forty other such recalls since 2002.
In this article, we’ll explore just what the heck is going on and whether or not you need to worry about this with your own smartphone.
Why Do We Use Batteries That Explode?
All of our portable electronic devices (i.e. phones, tablets, laptops) use Lithium-ion batteries. Pound for pound, Lithium-ion batteries provide far more energy than other types of batteries — around twice as much as Nickel Metal Hydride (NiMH) batteries and around six-times as much as the lead-acid batteries used in cars.
This is important in an industry where weight (or lack thereof) is a huge selling point. We all want our phones to be as light as possible yet still last at least a full day without recharging — and at the moment, Lithium-ion is the best technology we have that lets us do that.
But Lithium-ion batteries have a few disadvantages, too. They have a short shelf life, only lasting about 2–3 years from the date of manufacture, and that’s regardless of whether they’re actively used or not. If they fully discharge, they’ll never work again. And occasionally they explode.
To understand why this happens, it’s necessary to know a little about how Lithium-ion batteries work internally.
Like all modern batteries, they store and release energy through controlled chemical reactions. A current flows between two electrodes (an anode and a cathode) through chemicals called electrolytes. Lithium is highly reactive, which is what gives these batteries such a high energy density — but it also means that if something goes wrong, the results can be catastrophic.
So, What Can Go Wrong?
There are a few things that can go wrong with a Lithium-ion battery and they all involve overheating. If one part of the battery gets too hot, then it can lead to a chain reaction known as “thermal runaway” — the whole battery gets hotter and hotter until it ignites or explodes.
Because of this, Lithium-ion batteries have an on-board computer to ensure they don’t overheat. If this fails then overheating can occur, especially on a hot day or when the device is being heavily used. Overcharging can also lead to overheating, but again, the battery’s internal computer should prevent this. Unfortunately it may fail to do so, whether due to a manufacturing error or because the computer itself has sustained damage.
The anode and cathode also need to be kept separate or the battery will short circuit, redirecting energy to the electrolytes. In a Lithium-ion battery the electrolytes are highly flammable, and fire or explosion is all but inevitable if this occurs. Why would the electrodes ever touch? Again, maybe because the battery sustained physical damage or because of a manufacturing error (e.g. a defect in the material that separates the electrodes, the introduction of a foreign conducting material, etc).
Misusing or abusing the battery can also cause an explosion. Piercing the battery with a sharp object can cause a short circuit, while connecting it to an incorrect charger can cause it to overcharge or charge too quickly, which can lead to a build up of lithium on the electrodes, a short circuit, and ultimately an explosion.
What Went Wrong for Samsung?
It’s not yet clear exactly what the issue was with the Galaxy Note 7. The company has blamed “a very rare manufacturing process error” which caused the anode and cathode to come into contact. Further investigations are underway. Samsung has stated that none of its other products are affected by this issue, and there have not been a significant number of incidents involving their other products.
Remarkably, some people have decided that the Galaxy Note 7 is such a good phone, they’re going to hold onto theirs despite the risk. This is, to say the least, a rather reckless approach, and while the risk is small, it’s unnecessary to take it. There are plenty of good alternatives on the market, including some of Samsung’s other products.
Should You Be Worried?
Although the consequences of an exploding battery can be catastrophic, it’s an extremely rare event. You’re more likely to be struck by lightning — which would probably also cause your phone to explode! But there are some steps you can take to reduce the odds even further:
- Only use the original battery, or one from the manufacturer, or a reputable brand.
- Don’t leave your device in hot areas, particularly while charging. Keep it out of direct sunlight, and make sure it can dissipate heat effectively.
- Have a protective case for your phone to avoid puncture damage if you drop it. But take the case off if the phone gets too hot. The phone will almost certainly shut down before the battery gets hot enough to ignite, but the heat can still shorten the life of the battery.
- Do not use a cracked or swollen battery. Remove it from any device and do not attempt to charge it.
- Dispose of old or damaged batteries responsibly. Take them to a recycling center, or to a electronics retailer who will be able to dispose of them properly.
Until there’s a breakthrough in battery technology, we’ll be using Lithium-ion batteries on a daily basis. And the vast majority of us will never encounter a problem more serious than running out of power. If the Samsung debacle has you concerned, take care and know that you have pretty much nothing to worry about.
Did you buy a Galaxy Note 7? If so, are you one of the mavericks who’s keeping theirs? Have you ever encountered a battery explosion? Let us know in the comments section below.