How your lithium-ion battery could be an explosive danger
You spot an online advertisement for a replacement battery for your e-scooter that costs just S$30 – a staggering 10 times cheaper than the original one.
For many consumers, the choice is pretty obvious – so long as it does the job, go for the better bargain. But safety could be the trade-off here.
A recent episode of Talking Point showed just how lithium-ion batteries – used in personal mobility devices (PMDs) such as e-scooters, and electronic devices such as handphones, laptops and power banks – can pose fire risks.
Along with the growing popularity of PMDs here in recent years, there has been a spike in fire incidents involving them - a 52 percent increase in 2017 from the same period in 2016.
Most smartphones have a single cell battery, but a PMD’s battery pack can contain as many as 35 cells, noted Associate Professor Palani Balaya of the National University of Singapore Centre for Energy Research & Technology.
A battery pack for a hover board.
WHY BATTERIES GO BOOM
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 3 volts.
The cell was observed slowly bulging, and then it began to emit smoke before abruptly exploding in a spectacular orange burst.
“If this explosion happened at the pack level, it would be a very massive one,” he pointed out.
(Youtube: CNA Insider)
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 good BMSes, and are unable to stop charging, which is why they pose a fire risk, explained Dr Balaya.
In another demonstration, he 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. He warned:
"Every time a cell warms up, you are evaporating the liquid electrolyte into gas. The local pressure builds up and it leads to an explosion".
Batteries do carry certain certifications to show that they have been tested for safety. But this system is not fool-proof because the certifications may be easily duplicated.
Talking Point host Diana Ser went online to find out more about cheap batteries, discovering that many are unbranded, with the sellers unaware of where these batteries were made.
UNCERTIFIED CHARGERS ALSO UNSAFE
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.
In a recent crackdown here, 175 unregistered e-scooter chargers from various suppliers were seized by safety authority Spring Singapore.
Mr Jay Jin, who owns e-scoooter outlet Kernel Scooter, had to learn about applying for the SAFETY mark certificate when he set up shop about a year ago.
This process includes sending the power adapters’ blueprints to the relevant agencies, where they run vigorous tests to ensure these adaptors meet the safety requirements. The process takes about one to two months and costs about S$300 to S$400.
“There are some sellers, mostly home-based, who may not apply for this thing because of the cost factor,” he said. “And some may not be aware that all electrical appliances that involve batteries and power adapters need this certificate.”
A PMD charger with a SAFETY mark means that the voltage advertised on it is accurate, and the mark – which can be in the form of a sticker or engraved on the device – applies not just to PMD but also other chargers in general.
Handphones and even powerbanks which use lithium-ion batteries can overheat and explode when not charged properly.
DO SELLERS AND BUYERS CARE?
Despite this, some retailers Talking Point spoke to didn’t think the Spring SAFETY mark was important. One shrugged off the notion that a charger she was selling without the mark could be a fire hazard.
“There is no such thing, it won’t happen,” said the retailer confidently.
One consumer said that SAFETY mark or no, price came first. She explained: “For me, if I can charge my phone, I will just go for the cheaper option.”
Perhaps, though, it would be better to burn a small hole in one’s pockets buying a legitimate product - than to risk burning down one’s house.
Watch this episode of Talking Point here.