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Here's the real reason behind the exploding Samsung Galaxy Note 7 batteries

Shweta Sengar | Updated on: 10 February 2017, 1:45 IST

Imagine this: You buy a new smartphone. After trying it out all day and handling it with utmost care, you carefully plug it into the charger right before you go to sleep. You wake up to the smell of smoke, only to find that your phone has gone up in flames.

This has been the reality for a number of people around the world, who lined up to get their hand on the Samsung Galaxy Note 7. That's right, the smartphone that has reportedly recorded a whopping over 100 explosion instances.

Samsung has announced its plans to recall every single unit of Galaxy Note 7. This roughly amounts to 1 million of the 2.5 million units manufactured.

Samsung has halted the sales and shipments of the Note 7 and is working in collaboration with government agencies to provide easy refunds and exchanges for phones.

"As of 10 October, as many as five of the supposedly safe replacement Note 7 phones have caught fire as well, and Samsung is asking all users to shut down their phones. As of 13 October, Samsung is officially recalling every single Note 7, including replacement units", reports CNET.

So why are Samsung Galaxy Note 7 batteries exploding?

Like many other rechargeable devices, smartphones also use Lithium-ion batteries. These are energy-dense and operate under high power which makes them prone to catastrophic combustion. The liquid floating around inside the Lithium-ion batteries is highly flammable.

Overheating is the primary cause of explosions. While smartphones can record a spike in temperature owing to weather conditions or heat being transferred from other components, the Samsung Galaxy Note 7 is plagued with a faulty battery cell. This means that the battery generates more heat than the device can handle.

How it happens

"If the battery short-circuits by puncturing the extremely thin sheet of plastic separating the negative and positive sides of the battery, the puncture point becomes the path of least resistance for electricity to flow", explains CNET.

This heats up the flammable liquid at that spot - if it heats up too soon, an explosion is imminent.

Another cause of combustion is a faulty "battery management system". This system monitors the electric current and tells a chip inside the phone to stop the current flow once the battery is fully charged. If either one, the chip or system, is faulty, it would result in overcharge. The battery would continue to charge and would eventually become unstable and burst into flames.

Smartphones do not have fans or liquid cooling mechanism like gaming PCs. This means that the heat must radiate for the device to cool down. If the heat is generated faster than it is lost or dissipated, it could again lead to overheating, and eventually an explosion.

The battery material starts to break down once it reaches about 100ºC (200ºF). This triggers a chemical chain reaction that releases its own energy. This process happens so fast that the entire cell goes from being in one piece to being completely destroyed just in a matter of seconds.

Batteries are becoming unsafe due to higher demands of the manufacturers for better performance from a relatively smaller battery -a desirable feature in smartphones.

According to a unpublished preliminary report sent to Korea's Agency for Technology and Standards (obtained by Bloomberg), Samsung had a manufacturing error that "placed pressure on plates contained within battery cells," which "brought negative and positive poles into contact." This means that a punctured, thin plastic layer which separates the positive and negative sides of the battery.

The Samsung's replacement Note 7s were also reported to have faulty batteries even though those were from a different supplier.

If you own a Galaxy Note 7, you should strictly consider returning your phone, even if it is marked as a 'safe' model.

First published: 18 October 2016, 1:57 IST