In recent years, fire incidents caused by electric bicycle batteries are not uncommon, and have become a hot topic in media reports. In the face of this problem, many regions have begun to take strict measures, explicitly prohibiting the charging of electric bicycles and their batteries indoors to avoid potential safety risks.
According to the data, a total of 18,000 electric bicycle fires were reported nationwide in 2022, an increase of 23.4% from 2021; In 2023, the number of cases will rise to 21,000, an increase of 17.4% from 2022. The number of electric bicycle fire accidents is increasing year by year, but there are very few reports related to fire accidents related to small electrical appliances such as power banks and mobile phones. This raises a question: Obviously everyone is a "lithium battery", why do electric vehicles love accidents so much, but compliant power banks can be brought on the plane?
Image: AI-generated
In fact, although e-bike batteries may be similar in materials to small lithium-ion battery devices we use every day, such as mobile phones and power banks, they are fundamentally different in terms of design, usage conditions, and safety features. These differences have a significant impact on their performance and security, so let's talk about them in more detail below.
There is a gap in capacity
The first is that there is a significant difference in design and scale. E-bike batteries have a much larger capacity than mobile phones and power banks, and are usually measured in kilowatt-hours (kWh) or ampere-hours (Ah), while the latter is usually measured in milliampere-hours (mAh).
E-bike batteries need to provide enough energy to support the vehicle's long-distance driving, while the batteries and power banks in mobile phones only need to meet the power needs of everyday electronic devices. In order to meet the large capacity and high power requirements of electric bicycles, the battery is a battery pack composed of dozens or even hundreds of cells, and has a management and balance system to ensure the uniform charging and discharging of each cell, while mobile phones and power banks usually only contain a few battery cells, and the structure is relatively simple.
There are more cells in the e-bike battery, and the system is more complex, which means that there are more points of failure that may occur, and it also means that in the event of a fire, the e-bike battery will burn more vigorously and faster because of more "fuel", which will eventually cause greater harm.
An electric car in the stairwell that was being charged suddenly spontaneously combusted, and it exploded 3 times in just 15 seconds of the video!
The working and charging environments are different
During the use of electric bicycles, they will encounter various extreme environmental conditions, such as high temperature, low temperature, humidity changes, vibration and impact, etc., which may exacerbate the aging and wear of the battery, thereby increasing safety risks.
In contrast, mobile phones and power banks are usually kept in a more mild environment, and there are few bumps and vibrations during use, so the safety risks are relatively small.
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At the same time, people's habits of using electric bicycle batteries, mobile phones and power banks are also different. E-bike batteries often need to be charged at high power for long periods of time, sometimes without proper supervision, and some accidents have shown that chargers will connect multiple sockets in series or pull long wires to charge, which increases the risk of safety accidents.
In contrast, mobile phones and power banks usually have less charging power (even flash charging technology, the power is usually not as good as that of electric vehicles), and charging behavior is more frequent and dispersed, and users are more dependent on and concerned about these devices, so they tend to be more cautious in the use process and less likely to be risky.
To sum up, although e-bike batteries and small lithium battery devices are similar in basic materials, their performance and safety characteristics and safety requirements are quite different due to their essential differences in design concepts, usage scenarios, and safety requirements. In this way, we can understand why we should be strict about the battery of electric bicycles, but we are relatively relaxed about mobile phones and power banks.
So how can we make e-bike batteries safer?
Security is no small matter
Considering that once the e-bike battery fails, it may cause serious consequences, the e-bike battery system contains more layers and higher intensity safety protection measures, such as overcharge protection, over-discharge protection, short-circuit protection, thermal protection, etc.
At the same time, many big brands of electric bicycles are equipped with a battery management system (BMS) to monitor the parameters of the battery in real time and take measures to ensure safety if necessary. Although mobile phones and power banks also have some degree of battery management functions, these functions are relatively simple, and the main purpose is to extend battery life and improve efficiency.
In fact, Continental has made significant progress in the regulation of e-bikes, especially through the implementation of laws and regulations such as GB17761-2018 "Safety Technical Specifications for E-Bicycles" and CNCA-C11-16:2021 "Implementation Rules for Compulsory Product Certification for E-Bicycles", which provide clear production specifications and safety standards for e-bike manufacturers.
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These specifications not only stipulate the production requirements for e-bikes, but also strengthen the regulation of e-bikes through measures such as 3C certification to ensure that only certified products enter the market. These measures greatly improve the safety performance of newly produced e-bikes and help reduce safety accidents caused by product quality problems. The vast majority of current electric vehicle fire accidents are due to electric bicycles that do not meet standards, unauthorized modifications, especially battery modifications, and improper charging methods. It is believed that with the implementation of new standards, the elimination of old products, and the improvement of public safety awareness, electric bicycles will also be safer.
Planning and production
Author丨ZHANG Yun, Ph.D., Institute of Process Engineering, Chinese Academy of Sciences and University of Surrey, UK
Audit丨Shao Hanqi, Engineer of Zhejiang Zhongke Lide New Materials Co., Ltd
Planning丨Ding Kun
Editor丨Ding Kun
Reviewer丨Xu Lai Linlin