China is the world's largest country in the production and use of electric bicycles, with a national ownership of about 350 million and an average annual output of about 35 million. Electric bicycles are convenient, efficient, and not too expensive, which greatly meets people's rigid needs for short-distance travel. However, in recent years, electric bicycles have also caused many accidents and even casualties due to various reasons, which has aroused public concern. In addition to deploring, people have once again focused on the safety of electric bicycles.
A series of electric bicycle fire accidents that occur in various places, although the causes are not the same, often catch fire quickly, burn fiercely, release toxic and harmful gases, and even explode in serious cases, resulting in casualties and property losses.
Gao Weina, second-level commander of the Fire Supervision Department of the National Fire and Rescue Administration: It can reach the burning state in 30 seconds, and the temperature in the center of the flame can reach 1200 degrees Celsius in 3 minutes, and if it is indoors, the indoor temperature can be as high as 600 degrees Celsius, which will produce a large amount of toxic smoke. At present, there is no fire extinguishing agent specifically for electric bicycle fire fighting in our country.
Experts say that lithium battery fires are quite different from ordinary fires. Lithium battery is a kind of energetic substance, with the existing fire extinguishing agent such as dry powder fire extinguishing agent, there is almost no effect on lithium battery fire extinguishing; with carbon dioxide, heptafluoropropane can only extinguish the open flame, can not fundamentally inhibit the occurrence of fire, often will re-ignite; although the water sprinkler system cooling and extinguishing effect is obvious, but the water consumption is large, and the extinguishing time is long.
According to the statistics of the National Bicycle Association, as of the end of 2022, there were about 350 million electric bicycles in the mainland, with an average of one for every four people. Therefore, even if there is a small probability of an accident, it is not a small number in absolute terms. According to the statistics of the National Fire and Rescue Administration, since 2021, a total of 69,700 fires caused by faulty batteries in electric bicycles and buildings have been reported across the country, killing and injuring 884 people, and causing direct economic losses of more than 700 million yuan. So, why do electric bicycles have frequent fire accidents?
Gao Weina, second-level commander of the Fire Supervision Department of the National Fire and Rescue Administration: Electrical failure is the most important reason, accounting for 78%, of which battery thermal runaway accounts for 44%. First, the intrinsic safety of the whole vehicle and battery products is not up to par, and the lithium batteries sold in the market are mixed, and many are even "three no" products; second, the problem of illegal modification is prominent; third, electric bicycles enter the building to charge at home, causing mass deaths and injuries.
The reporter launched an investigation in Nanning, Guangxi. With the assistance of the traffic police, we randomly inspected some vehicles and found several outstanding problems. The first is to modify the battery in violation of regulations, in order to run further, the courier brother installed a spare lithium battery on the basis of the original lead-acid battery. Because the battery compartment was already occupied, he simply put the spare batteries in the suitcase.
According to the national standard, the battery should be fixed in a special battery pack box, and the maximum gap between the battery and the side wall of the battery pack box should be less than or equal to 30mm, and it should not shake. Not only did the courier use the suitcase for the battery, but the fixed battery actually used foam and plastic bags. Not only that, but he also made changes to the line and structure of the car. The investigation found that there were not a few illegal modifications to the battery. The main purpose of the modification is to run faster and farther.
In April 2019, the "Safety Technical Specifications for Electric Bicycles", which is often referred to as the new national standard, was officially implemented. It stipulates that the speed of electric bicycles shall not exceed 25 km/h, the weight of the whole vehicle shall not exceed 55 kg, and the battery voltage shall not exceed 48 volts. However, many people believe that the new national standard cannot meet the actual demand, especially high-frequency users such as takeaways, express delivery, substitute drivers, small traders, and enthusiasts, so they have been modified.
At present, there are more than 10 million riders in the country who use electric bicycles as their operating tools, and some of them tend to be equipped with at least one backup battery, most of which are modified batteries, in order to run more quickly. In addition, in order to match the modified battery, the vehicle structure, size, and wiring are often modified. Although these practices are against national regulations, many people still choose to retrofit. The modification is usually carried out at the maintenance point, and the reporter came to Nanning Zhonghua Road, where the maintenance point is more concentrated.
Here the reporter saw: the lead-acid battery is changed to a lithium battery, and the small-capacity battery is changed to a large-capacity battery, which is a modification demand often put forward by general car owners. Although these are all against national regulations, they can be changed at the maintenance point.
According to the provisions of the new national standard, the battery voltage does not exceed 48 volts, but it can be changed at will here, 60 volts, 72 volts and even higher.
The survey found that the original lithium battery of the same power usually sells for thousands of yuan, while the cheap modified battery only sells for a few hundred yuan, so many people will buy modified batteries, but it also buries the hidden danger of accidents. The battery cells of modified batteries are usually second-hand batteries that have been eliminated from electric vehicles, but the black workshops are old and shoddy, and the safety protection is seriously lacking, which cannot meet the national standards at all. However, on short video platforms, many businesses have publicly displayed the battery modification process to attract business.
In the face of the chaotic modification market, the local market supervision and management department does not seem to have a good solution, and only 88 cases were investigated and dealt with last year.
Jiang Zhiying, Chief of the Law Enforcement Supervision Section of the Nanning Municipal Market Supervision and Administration Bureau, Guangxi: Each modified vehicle will be punished according to the standard of 1,000 yuan. Modifying electric bicycles, especially the work of modifying transmissions and installing batteries, can be completed in a short time, about half an hour, which puts forward great requirements for the time, frequency and intensity of daily supervision and inspection.
Modified batteries like this that do not meet national standards are prone to accidents. According to the Beijing Fire and Rescue Corps, e-bike fires caused by battery failure account for more than 90% of the total number of accidents. Most battery failures are caused by illegal modifications.
As a comparison, let's see how regular battery manufacturers ensure battery safety. First of all, from the battery cell, the regular manufacturer uses a lithium iron phosphate battery with higher safety.
Huangfu Dongyang, assistant to the chairman of a new energy company in Guangxi: Because its structure is relatively stable, the battery performance is relatively stable. At the same time, the BMS system is added to it, and the battery management chip is implanted in the battery management system, and the data of various electrical properties of the entire battery are extracted and controlled by writing programs.
The BMS system is also the battery management system, which is equivalent to the brain of the battery, and it can even remotely manage each battery. These safety precautions are not available for modified batteries.
Huangfu Dongyang, assistant to the chairman of a new energy company in Guangxi: including the voltage status of the battery, the remaining power signal, etc., can be displayed, and in the case of high temperature alarm, the power can be cut off to reduce the risk.
The fire accident caused by the electric bicycle is not only because of the use of illegally modified batteries, but also because of the modification of the body, including the body structure, motor power, wiring, etc., but at the maintenance point, these can all be changed. Even the brain of an e-bike, the controller, can be changed at will. There are countless videos of various modifications on the Internet.
Industry insiders said that replacing the original battery with a large-capacity battery may lead to a mismatch between the technical parameters of the battery power and weight and the parameters of the main components such as the charger, speed controller, and motor of the electric bicycle, which may cause problems such as short circuit or thermal runaway during charging and use, causing fire.
Li Denghua, production process manager of an electric vehicle company in Guangxi: electric bicycles are not just parts patchwork, we must treat it as a whole design, including the rationality of the research and development structure, the rationality of the vehicle process layout, the high quality of the parts, and the rationality of the safety design of the parts, in order to ensure the factory safety of the electric vehicle, not only the battery.
In order to prevent fire accidents caused by modified batteries during charging, some charging pile companies have adopted restrictive technical means on charging piles, so as to improve charging safety.
At present, Continental only has recommended standards for lithium-ion batteries for electric bicycles, but there are no mandatory standards. It is understood that the mandatory national standard "Safety Technical Specifications for Lithium-ion Batteries for Electric Bicycles" has passed the drafting and solicitation of opinions stage and will be issued soon.
Illegally modified e-bikes go faster and go farther, but this comes at the expense of safety. Industry insiders pointed out that at present, there are no special laws and regulations for the illegal demolition and modification of electric bicycles, so the punishment measures for illegal modification of electric bicycles can only be based on administrative penalties, which is difficult to play a deterrent role. It is suggested that laws and regulations should be further improved to effectively bring into play the binding role of legal norms. Here we would like to solemnly remind consumers that they must buy regular and qualified vehicles and accessories, replace old batteries regularly, and do not modify electric bicycles in violation of regulations.
Source: CCTV News