The rising popularity of electric b
Electric bicycles have surged in popularity in China over the last decade, championed for their efficiency and minimal environmental impact. Yet, the boom has not been without its drawbacks.
On February 23 in a residential complex of Nanjing, capital of Jiangsu Province, fire suspected to have been caused by the lithium-ion battery of an electric bicycle resulted in 15 fatalities and 44 injuries. The blaze started on the ground floor of a 34-story building, where electric bicycles were parked. The exact cause is still under investigation.
The tragedy caught the public’s attention, not only because of the human toll but also because fires related to electric bicycles have been on the increase.
By the end of 2022, there were an estimated 350 million electric bikes in China, equating to one for every four people. Shanghai led the nation with over 10.5 million registered electric bicycles.
Last year, the National Fire and Rescue Bureau reported 21,000 fire incidents related to electric bicycles, a 17-percent rise from the previous year. In Shanghai, bicycle fires rose by about a third to 1,020, resulting in seven deaths and 23 injuries, according to the city’s Fire and Rescue Brigade.
This phenomenon is not confined to China. In the first half of 2023, the London Fire Brigade was called out to an electric bike fire an average once every two days — a 60 percent increase from the same period a year earlier, Bike Radar website reported.
Bike Radar cited three common causes of the fires:
•Electrical:
typically due to overcharge or over-discharge. It can be due to incompatibility between the battery and charger, a sub-standard battery or an external short circuit.
•Mechanical:
triggered by crushing or penetration of a battery with an external object, or an extreme or repeated impact.
•Thermal:
Extreme high and low temperature environments.
Locally, e-bike fires continue to pop up in the news.
A recent fire started by an electric bicycle in an underground garage on Wuning Road in Shanghai’s Putuo District quickly spread smoke throughout a residential building. Thanks to a second-floor extension platform, residents found safety while awaiting rescue. No one was injured.
“The smoke was very thick, with a pungent smell,” said a resident surnamed Chen, adding that visibility in the area was greatly reduced.
A fire rescue officer in Putuo explained that, aside from the metal frame, electric bikes are mostly made of plastic and rubber, producing significant noxious smoke when burned. That can quickly
increase carbon monoxide levels in enclosed spaces.
One problem is the desire of many e-bike owners to prolong battery life and attain higher speeds by replacing original batteries with larger ones, said He Penglin, deputy director of the China Electronics Standardization Institute’s safety technology research center.
These modifications often lead to overcharging and overheating, greatly increasing the risk of fire, he told China Central Television.
Despite safety standards limiting electric bikes to a maximum speed of 25 kilometers per hour and batteries to 48 volts or less, higher-voltage batteries are readily available on online platforms.
Exacerbating risk, some bike owners use “flying wires,” or electrical extensions running from their apartments upstairs to electric bicycles on the ground, to recharge batteries.
Then, too, some take batteries into
r homes for charging. hanghai’s regulations, effective since 2021, ban charging electric bikes uilding common areas, emergency cuation pathways and crowded inr spaces. owever, many ignore the rules. 2023, a courier in Shanghai’s Ming District caused a fire by using a ing wire” to charge his bike battery. ocal court handed him a two-year pended prison sentence. nce February 27, Shanghai’s fire ade has initiated nightly safety inctions in residential areas, targeting dings with centralized electric bikerging garages. uring the inspections on Febry 28 alone, more than 1,000 ety hazards were detected in 247 l communities. the Dongyuanfang community in wntown Huangpu District, for innce, electric bicycles were found to be charging in hallways, and fire exit passages were blocked with flammable materials.
At the Green Mansion community in Jiading District, residents were found to be charging their electric bikes inside buildings.
A Hongkou District community Party secretary told Shanghai Daily that the limited number of outdoor charging ports and higher fees at public charging stations deter their use in favor of cheaper charging at home.
Over 95 percent of Shanghai’s 13,000 residential communities now have electric bicycle charging facilities — mostly managed by private companies, according to the Shanghai housing authority. But demand often outstrips supply.
“Adding more stations meets resistance from some residents, who fear increased fire risks near their homes,” the Party secretary told Shanghai Daily.
Cost is a major factor. Fully charging an electric bicycle at home costs about 0.6 yuan (8 US cents), while public charging ports charge about 1 yuan for four hours.
An electric bike owner surnamed Jiang told Shanghai Daily that charging an electric bike in the public garage in his neighborhood incurs an additional monthly parking fee of about 150 yuan.
“To boost charging-station use, we should lower electricity rates to align with home-charging costs,” the community official said.
She also suggested incorporating electric-bicycle charging facilities into urban infrastructure planning to make outdoor charging safe, convenient and affordable for the public.
One new solution for safe charging is the emergence of smart battery exchanges and charging cabinets on Shanghai streets and in some communities.
Riders can either charge their batteries in the cabinet and then reinstall them on their electric bikes or swap their depleted battery for a fully charged one.
These cabinets, operated by both stateowned companies like China Tower and private firms, feature high-temperature alarms and automatic fire extinguishing systems, ensuring battery charging safety for residents and public alike.
A delivery rider surnamed Wu told Shanghai Daily that he and many of his colleagues now use battery-exchange cabinets instead of charging at dormitories where they live.
“The stations, which charge 299 yuan per month, offer a convenient solution for riders, especially during peak delivery times, allowing us swift swap of batteries that can run for 60 kilometers,” said Wu.
A pending national standard for lithium-ion battery safety is also in the works.
Electric bike batteries have far fewer cells than the batteries in electric cars, but bikes generate more safety risks, said Ma Guilong, a retired professor from Tsinghua University.
“The safety concern of bike batteries is more about proper management than about technology,” Ma told China Newsweek.
Many domestic cities such as Beijing have established local technical standards for lithium-ion batteries that power electric bicycles.
The National Standardization Management Committee’s website states that a mandatory standard for bike batteries, drafted in 2022, is in the public feedback stage.
“This standard will fill a gap at the national level for the technical basis of quality supervision of lithium-ion batteries used in electric bicycles,” standardization institute’s He said.
Once the standard is implemented, products and services that fail to comply will not be allowed to be produced, sold or imported.
The safety concern of bike batteries is more about proper management than about technology.
Ma Guilong Retired professor from Tsinghua University