A video has been released which graphically shows what happens when a lithium ion battery is overcharged.
In short, it explodes.
A special programme by Channel News Asia reveals how this happens and also spotlights the dangers of using battery chargers that are wrong for your electronic device.
Experiments were carried out by Associate Professor Palani Balaya of the National University of Singapore Centre for Energy Research & Technology.
He explained that while a lithium-ion battery is being charged the ions move from the positive to the negative electrode at a fairly high voltage of 3.7 volts - much higher than the 1.5 volts in a typical alkaline battery.
These ions move through a liquid electrolyte which is highly flammable – and that is why when one overcharges a lithium-ion battery, it overheats and can even explode.
To demonstrate, Dr Balaya overcharged a single battery cell, applying more than 5 volts instead of the recommended 4.3 volts.
The cell was observed slowly bulging and then it began to emit smoke before abruptly exploding in a spectacular orange burst.
To see this go to https://www.youtube.com/watch?time_continue=8&v=CkEkFjoFPlA
Dr Balaya said: “If this explosion happened at the pack level it would be a very massive one.”
This is why every rechargeable battery contains a battery management system (BMS) that prevents it from overcharging.
However, inferior quality and non-original batteries often do not have a good BMS and are unable to stop charging which is why they pose a fire risk.
In another demonstration, Dr Balaya showed how the temperature inside a battery from a reliable manufacturer did not rise beyond 3°C during the charging process - while another battery from an unreliable source heated up by as much as 10°C.
While the consequences of using a cheaper and potentially unreliable battery can be dire, using an inappropriate charger can be just as disastrous.
A certified charger will typically feed the correct prescribed electric current for the battery. One not from the same original supplier as the battery could feed too high a current, sparking a fire.
* Several major airline companies now use AvSax fire containment bags in case electronic devices, including phone chargers, catch fire mid flight.
They are used to deal with burning electronic devices ranging from laptops and mobile phones to e-cigarettes.
They were deployed on aircraft 20 times in 2017.
If an electronic device starts to seriously overheat or emit smoke the cabin crew will pour at least two litres of water into an AvSax and then drop the burning device into the bag, adding additional water as required. The water activates the polymer gel inside the bag causing it to expand around the device. Should the device keep on venting then the AvSax is tough enough to absorb the force.
The AvSax cools the batteries in the device, reducing the likelihood of the battery catching fire but if it does go into what is known as thermal runaway when all the battery cells catch fire at incredibly hot temperatures it is all contained within the bag.
Amazingly, the water is absorbed into the internal lining of the bag so the device is dry when it is removed.
