The picture shows a warning notice. Screenshot of the official Weibo of Beijing Firefighting
html At around 3 a.m. on the 120th, a fire in a community in Tongzhou, Beijing killed 5 people, causing an explosion in the charging of electric bicycle batteries in the home. This is another tragedy caused by electric vehicles. In recent years, electric bicycles have become an important means of transportation for short-distance travel for the general public, but at the same time, casualties caused by electric bicycle fires have occurred frequently. The fire hazards exposed by electric bicycles during charging have become the focus of attention of the whole society.-
At present, my country's electric bicycle ownership is about 300 million, and one out of every 4 people rides. This data is still growing at a rate of 30% per year. With the huge number of electric bicycles in hand, vehicles are in frequent situations of fire and explosion. Let’s first look at a set of data for 2020: 16.9% of the 65 major fires in the country were caused by electric bicycles. In recent years, the major casualties caused by electric bicycles have also been shocking. For example, in 2020, an electric bicycle charging failure in Baoshan, Shanghai caused a fire, causing 5 people to die; in 2019, several electric bicycles and debris on the first floor of a house in Qinzhou, Guangxi, causing 3 deaths and 3 injuries; in 2018, a charging electric bicycle caught fire, causing 4 deaths; in 2017, a short circuit of the electric bicycle electrical line in Taizhou, Zhejiang Province ignited the surrounding combustible materials; 11 people died and 2 seriously injured.
In recent years, the government has successively introduced relevant measures to block related hidden dangers. Due to the increasing number of fires caused by electric bicycle electrical failures and charger failures in recent years, the new national standard of "Electric Bicycle Safety Technical Specifications" was officially implemented in 2019, putting higher requirements on the safety performance of electric bicycle power batteries. Electrical safety and charger safety content have been added and improved in the content.
On August 1, 2021, the "Regulations on Fire Safety Management of High-rise Civil Buildings" officially implemented mentioned that if electric bicycles are parked or charged electric bicycles in public halls, evacuation walkways, stairwells, and safety exits of high-rise civil buildings, if they refuse to correct the correction, the fire rescue agency shall order the correction, and shall impose a fine of not less than RMB 2,000 and not more than RMB 10,000 on business units and individuals, and a fine of not less than RMB 500 and not more than RMB 1,000 on non-operating units and individuals. Make electric bicycle owners afraid to park stairwells, walkways and other places that are likely to harm the public.
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Why does an electric bicycle suddenly catch a fire? While bringing us convenience, it also leaves safety hazards around us. In short, it is still related to the electric bicycle battery. Currently, there are three commonly used batteries for electric bicycles: primary batteries (dry batteries), lead-acid batteries, and lithium-ion batteries. Lithium batteries are the most widely used, such as some mobile phones, computers, electric bicycles, electric vehicles, etc., which are used in lithium batteries. Most of the batteries in the event of an electric bicycle accident are lithium-ion batteries. Lithium batteries are made up of thin sheets such as positive and negative electrode layers, electrolytes, and separators. A slight damage to this structure will cause a fire. Why does
lithium battery spontaneously ignite? There is only one final cause of
- short circuit, and there are probably the following reasons for short circuit:
is puncture of foreign objects. There is a layer of separator between the positive and negative electrodes inside the lithium battery. Once a foreign object pierces, the separator will be damaged, which will cause a short circuit and heat inside the damaged lithium battery, which will eventually cause the entire battery pack to catch fire.
The second is external impact. External forces may cause damage to the internal structure of the lithium battery or the shell to be damaged. Once the internal structure of the lithium battery is damaged due to external force impact, it is easy to cause electrode short circuit or electrode exposure, and the damaged battery will heat and burn.
is internal short circuit. Currently, there are large parts of the electric vehicles that have spontaneous combustion on the market. The lithium battery is aging or the battery itself is unqualified, causing internal short circuits. This situation generally has no signs and cannot be stopped when there are signs of spontaneous combustion.
Once the electric car catches fire and explodes, the consequences are very terrible. A fire department previously conducted a short circuit and fire test on an electric car. Once the electric car catches fire, the combustion speed is very fast. It only takes about 10 seconds for an electric car to burn to a thousand degrees in 3 minutes! At the same time, it will be accompanied by a large amount of toxic thick smoke, which is very easy to cause casualties.
knows the dangers of electric vehicles. Everyone must keep in mind these "five principles" when charging:
1. Do not charge the electric vehicle battery for a long time and replace the aging battery in time;
2. Do not modify the electric vehicle battery and circuit privately;
3. Do not remove the speed limit device of the electric vehicle;
4. Do not buy inferior chargers for cheapness;
5. Do not charge in indoor environments such as stairwells, aisles or rooms.
