Should battery vehicles be banned from entering residential areas? After the Nanjing Fire

After a fire killed 15 people in a community in Yuhuatai District, Nanjing, the topic of fire hazards of two-wheeled electric vehicles has once again attracted attention.

Recently, several communities in Tianhe District, Guangzhou announced plans to ban electric bicycles from entering the communities, triggering heated discussions among residents. Netizens are confused. Most of the previous fire protection propaganda emphasized that electric bicycles cannot be charged at home. Now, can they not be parked downstairs or even entered into the community?

Some netizens believe that battery cars have repeatedly caught fire. In addition to improper charging, is there also a quality problem? Why can't we strictly inspect and eliminate fire hazards when leaving the factory, instead of not being allowed to park due to choking?

350 million battery cars and rising fires

The number of fires caused by e-bikes is indeed increasing.

The National Fire and Rescue Service will publish detailed data on e-bike fires starting in 2021. Data shows that in 2021, nearly 18,000 fires caused by electric bicycles and their battery failures were reported throughout the year, killing 57 people.

In 2022, 18,000 electric bicycle fires were reported, an increase of 23.4% from 2021, and 3,242 fires caused by battery failures in residential premises were reported, an increase of 17.3% from 2021.

In 2023, a total of 21,000 electric bicycle fires were reported across the country, an increase of 17.4% compared to 2022.

The number of fires caused by electric bicycles is increasing year by year, which is related to the increase in their ownership.

According to data released by the China Bicycle Association, as of the end of 2022, the number of two-wheeled electric vehicles in my country's society will be about 350 million, which is more than 30 times that of electric vehicles and higher than the overall number of cars. This is equivalent to 1 out of every 4 Chinese people owning an electric bicycle.

So, what causes electric bikes to catch fire?

According to data released by the Fire and Rescue Bureau of the Ministry of Emergency Management, 80% of fires caused by battery cars are caused while charging; and 90% of cases causing casualties occur in places such as hallways and stairwells.

This sentence implies two elements: one is the problem of electric vehicles themselves, and the other is environmental factors.

Let’s talk about the first one first, why do electric bicycles easily catch fire when charging?

Most of this can be attributed to the quality problems of electric bicycles, especially batteries, such as battery thermal runaway during charging, spontaneous combustion of electric vehicles, short circuits of electric vehicle lines, electrical faults, etc.

The most frequent cause of fires is thermal runaway and ignition of batteries during charging. Sometimes electric vehicles that are not charging can spontaneously ignite, also due to battery thermal management failure or battery short circuit.

There are also cases where individual owners of electric bicycles have modified their vehicles and purchased non-original batteries. For example, Wu Mouhai in Guilin, Guangxi purchased a lithium battery that did not meet safety standards and installed it on an electric bicycle. During charging, the battery ran out of control and exploded, causing a fire.

Why are electric bicycle batteries so easy to run out of control and explode? Why can there be so many non-original batteries on the market?

There are two types of batteries for electric bicycles: lead-acid batteries and lithium batteries. The former has mature technology and stable performance but is heavy and bulky. The latter has high energy density, high charging efficiency but high cost, is sensitive to temperature, and is more prone to overheating. , fire and explosion risk.

The new national standard stipulates both voltage and vehicle weight, and lithium batteries have begun to rapidly enter the two-wheeled electric vehicle market. In 2017, the market penetration rate of lithium batteries was only 10%. It will increase to 24.5% in 2021, and will be around 19.5% in 2022.

Judging from fire cases, battery thermal runaway ignition almost always occurs in lithium batteries.

However, safety issues cannot be attributed to lithium batteries. In fact, the problem is not lithium batteries, but inferior and irregular lithium batteries.

Unlike the new energy vehicle industry, the electric bicycle industry is filled with lithium battery products of varying quality and informal enterprises.

According to statistics from the Chinese Enterprise Database, as of now, there are only 1,496 major companies in China's power lithium battery industry.

However, Qichacha data shows that there are currently more than 60,000 domestic lithium battery-related companies, of which small and micro enterprises account for more than 60%, and companies without patent information account for 65%.

According to industry insiders, a set of regular 48-volt 24-Ah lithium batteries suitable for two-wheeled electric vehicles costs about 2,000 yuan. We checked the e-commerce platform and found that a set of regular brand lithium batteries with 48 volts and 20 ampere hours sells for close to 2,400 yuan.

However, the price of mainstream electric bicycles is only 1,500-3,000 yuan! It can be seen that the investment cost of the battery management system is extremely low.

In order to control battery costs, some electric bicycle manufacturers even use disassembled old batteries, which greatly increases the risk of accidents.

In 2022, the State Administration for Market Regulation conducted random inspections of 295 batches of products from 262 electric bicycle and electric bicycle battery companies, and the unqualified rate in the spot inspection reached 21.0%.

Among the manufacturers of substandard products, well-known companies such as Yadi and Xinri are also involved.

In our statistics, the severity of fires is closely related to the environment.

We have found that fires caused by electric vehicles are often accompanied by users charging their electric vehicles indoors. When electric vehicles are charged indoors, the continuous charging time will first appear to be too long, which can easily cause the battery to overcharge, pierce the internal diaphragm, and cause short circuit and thermal runaway. At the same time, indoor ventilation is poor, the temperature is high, and there are many combustibles, making it more difficult to escape from a fire and easily causing more serious fires.

Nowadays, it is a consensus that charging at home is not allowed, but in the fire in Nanjing, the battery car that caught fire was not in the residents' homes, but on the elevated floor downstairs.

It is worth noting that the serious consequences of the fire are actually related to the charging of the overhead layer and the building structure of the residential building.

Since most of the e-bike body is made of flammable and combustible materials, the maximum instantaneous temperature can reach thousands of degrees Celsius 4 minutes after a fire breaks out, and black smoke is diffuse, and visibility is basically zero.

The overhead floor of the residential building where the fire broke out was connected to the lighting well, and the fire and smoke spread across households and floors along with the lighting well. Therefore, in addition to the residents on the lower floors, the floors with the most severe burn marks on the facades are located on the 21st to 34th floors and other high-rise buildings. The poisonous gas produced by the combustion of electric vehicles is enough to suffocate people to death within 100 seconds, which is also one of the reasons for serious casualties.

It can be seen that the causes of fires caused by electric bicycles include both their own quality problems and environmental factors.

To cure this problem, both aspects of management are indispensable.

At present, the mandatory national standard "Safety Technical Specifications for Lithium-Ion Batteries for Electric Bicycles" is in the process of approval, and a new wave of centralized rectification of electric vehicles entering buildings and homes is also underway in various places.

Treating the symptoms must also address the root cause. How to make electric bicycles no longer a "ticking bomb" requires improvement and implementation of regulatory standards, establishment of market thresholds, and inspections during use. This is a systemic management issue that cannot be solved overnight.