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The continuous high temperature and scorching heat. Can electric cars be charged in such a hot day?Xiao Chen, who is doing an internship during the summer vacation,After visiting customers, before recharging my electric scooter, I always take out my mobile phone, open the Ninebot App, check the battery level and temperature, and decide whether it is appropriate to find a place to charge my car.

Ms. Wang used to worry about her commute to work every winter when she heard that cold weather was coming: she was afraid that it would be too cold and the battery of her electric bike would stop working or not be able to charge; in the summer, she was afraid that the electric bike would overheat and become unsafe...

After all, overcooling or overheating during battery charging and use have always been the biggest safety risks.

Since switching to Ninebot, their safety and range anxieties have been greatly alleviated, and there are many other citizens who have benefited from this. Ninebot recently conducted public welfare science education on electric vehicle safety in Nanjing, Jiangsu, Wuhan, Hubei, Hangzhou, Zhejiang, and other places, in collaboration with firefighters, traffic police, and market supervision. This also gave us a glimpse into their efforts and contributions to battery safety.

A "core" fundamentally guarantees safety

The battery cell is the key to the safety of electric vehicle batteries.

According to Pang Xu, a battery safety expert at Ninebot, Ninebot cooperates with domestic first-tier brand suppliers to produce its battery cells. However, Ninebot does not simply purchase products from suppliers, but develops and designs them from the source and customizes them according to the needs of user scenarios.

For example, the lithium battery charging problem that Ms. Wang is worried about is the feedback received from users when Ninebot was first established: when the outdoor temperature is below 0℃, electric vehicles cannot be charged and start slowly. Therefore, Ninebot developed a lithium battery pack that can be charged at -10℃. Importantly, in this way, users no longer need to charge the battery indoors because it is cold outside, solving the major safety hazard of indoor charging from the source.

Pang Xu introduced that Ninebot has also developed and put into production batteries that can be charged at -20℃. In the future, electric vehicles will be more convenient to use in winter in central and even northern China!

On November 1 this year, GB 43854-2024 "Safety Technical Specifications for Lithium-ion Batteries for Electric Bicycles" will be officially implemented. For single cells, six test items must be passed, including marking, overcharging, overdischarging, external short circuit, thermal abuse, and puncture. For battery packs, 22 test items must be passed, divided into four categories: electrical safety, mechanical safety, and environmental safety. As one of the main drafting units of the standard, Ninebot actually applied these strict new requirements to its own products a year ago, and conducted sufficient safety tests of higher standards such as high temperature, low temperature, rain, and electrical connections for the entire vehicle through its own Ninebot laboratory and commissioned external laboratory tests.

An App that makes you feel more at ease

What made Xiao Chen develop the habit of opening his phone to check the App before using an electric bike was the "Ninebot Travel" developed by Ninebot. In fact, what users see on their phones is only the most intuitive application level, or in layman's terms, a small part of the iceberg floating on the sea. Behind this "Ninebot Travel" is a very powerful car networking system.

For example, Xiao Chen can determine whether his car is suitable for charging and whether it can be fast charged from the mobile phone app. In fact, the Ninebot battery pack is connected to the Ninebot car operating system, which supports communication data reporting, power limit function, charging upper limit function, OTA upgrade support, fast charging and other functions. The system will monitor the temperature, current, voltage and other aspects in real time and continuously monitor the data of each battery cell. Once the battery temperature is too high or the power is cut off, the battery's built-in communication function and the 4G module on the Ninebot electric vehicle will collect the information to the Internet of Vehicles system. After cloud-based big data analysis, the risk will be judged earlier than the owner himself, and the warning will be sent to the owner through the App and mobile phone text messages.

Moreover, this system has several additional easter eggs:

Bicycle fall reminder - in case a cyclist accidentally falls, "Nine Travel" will automatically call the pre-set emergency contacts!

Positioning function - from now on, my mom is no longer worried about me losing the car!

"Handshake" again and again to solve mileage anxiety

Citizens who rely on electric vehicles as their main means of transportation should be familiar with "range anxiety": the most feared thing is that the battery is not enough to run. Although fast charging can be used in emergencies, it also brings new safety issues: overheating and reduced range. Ninebot's solution lies in the "handshake" between the battery and the electric vehicle, a self-developed system called BMS.

Pang Xu, a battery safety expert at Ninebot, told reporters that battery fires and explosions are caused by external factors other than the battery itself, such as overcharging, overcurrent, overload, etc., which indirectly lead to short circuits and thermal runaway of the battery. In response to this, they developed their own intelligent BMS to provide all-round active and passive safety protection.

For example, when charging, the charger and battery will adapt their power at different temperatures to avoid overcharging in high and low temperature environments.

For example, when the user is riding, the BMS will adaptively adjust to gradually reduce the vehicle's power output and capacity, and stabilize the battery temperature below 60 degrees.

For example, by developing larger capacity mass-produced batteries (48V/30Ah) and high-power chargers (20A), the battery life can be increased to more than 80 kilometers, while the charging time is reduced to 2 hours.

In addition to automatically cutting off the power when charging is completed to protect the battery from overcharging, BMS will pay more attention to the cultivation and guidance of user safety habits: users can set the charging limit, charging power, and full charge reminder.

The above functions are achieved through the repeated exchanges between the charger and the battery during each charging process. Pang Xu figuratively compares it to a "handshake". Through the "handshake", the charger can judge the health of the battery: whether it can be fast charged, automatically reduce the charging speed in high temperature environments, and automatically cut off the power when fully charged...

Pang Xu concluded: The key to battery safety is the battery cell, battery pack and battery management system. In terms of battery cells, Ninebot has established a car network by superimposing a national standard laboratory database to monitor the entire process of each battery cell from birth to scrapping; in terms of battery packs, it conducts higher standard safety tests on the entire vehicle through its own laboratory; and the independently developed battery management system BMS not only has more complete functions, but also uses its own "Ninebot Protocol" to prevent the use of third-party modification software and ensure the safety of the entire vehicle.

Of course, no matter how safe the equipment is, it cannot compare to the safety awareness of every consumer. As a company with a sense of social responsibility, in addition to strict requirements on products, Ninebot also actively participates in and organizes a series of popular science activities to let more people understand electric vehicles and use them safely.