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How to judge whether an electric bicycle is qualified? What tests does a qualified electric bicycle have to go through? On August 14, the Chutian Little Reporter Group went to the Zhuankou Testing Base of Wuhan Product Quality Supervision and Inspection Institute, transformed into "little quality inspectors", followed the quality inspection experts, experienced the whole process of electric bicycle safety testing, and gained a lot of new knowledge and unforgettable experience.

Next, let us witness the growth of the young reporters through their essays and paintings.

Electric bicycle safety science tour

Huang Yuhan, Class 2 (6) of Wuhan Shanying Primary School

On the morning of August 14, our group of young reporters followed the reporters from Jimu News into the Wuhan Product Quality Supervision and Inspection Institute.

First, we went to the conference room on the third floor of the Wuhan Quality Supervision Institute to learn professional knowledge about electric vehicle batteries. The teacher talked about cases in life. Most of the explosions and fires of electric vehicle batteries were caused by modified batteries. Then the professional lecturer explained to us the difference between modified batteries and original batteries. The battery is mainly divided into three parts. The innermost part is the battery cell. We can imagine them as children holding hands. BMS is like a class teacher, managing students to abide by discipline and not run around. Imagine the outer shell as a classroom, to shelter them from wind and rain, so that they have a better environment for class. For modified batteries, BMS will be like when the teacher is not in the classroom during self-study, and the naughty students will not obey and run around. The shell of the original battery will be harder. If it is not a particularly strong impact, it will not have any problems. The modified battery is not so hard. If it encounters a large impact, the battery cell will fail and catch fire and explode.

When charging an electric vehicle, do not charge it with flying wires, do not charge it for a long time, do not charge it at the entrance of the fire escape staircase, do not bring the electric vehicle or its battery into the elevator or charge it at home, ride it to the community's dedicated electric vehicle charging shed to charge it, and use the original electric vehicle wire to charge it. Do not modify the battery and electric vehicle without authorization. Modifying the headlights will short-circuit, modifying the wiring will cause malfunctions, and modifying the acceleration will cause the brake system to fail.

After learning theoretical knowledge in the conference room, we went to the electrical center and visited various tests for electric bicycles. The first test point is whether the brake is powered off, the motor power and the maximum speed. It is qualified if it is less than 25 kilometers per hour. The second test point is to test the handlebars. Rotate the handlebars to 1600 Newtons to see if there is any bending or breaking. 1600 Newtons is about 160 kilograms. Simulate emergency braking, steps, etc. to test the anti-bending characteristics of the handlebars. The third test point is to measure the strength of the frame and the front brake assembly. The fourth test point is to test the braking distance. How far does it take to stop when braking. The fifth test point is heavy object impact, to test the strength of the front fork assembly. The sixth test point is to measure the size, measuring the center distance, center wheelbase, body height, seat height, rear hanger width, etc. The rear hanger width must be less than or equal to 175 mm. The distance from the pedal to the ground is tested to prevent the pedal from rubbing against the ground when the electric vehicle turns. Finally, weigh the electric vehicle, requiring it to be less than or equal to 55 kilograms.

The battery compatibility is tested in a radio darkroom. There is no signal at all when the door is closed, and the mobile phone has no network, which is a signal shielding environment. Electric bicycles must be anti-interference, neither being disturbed by the external magnetic field nor interfering with the outside world.

The motor should be less than 400 watts. If the power is too high, it will be difficult to control. The speed of the electric vehicle is related to tire pressure, weight (the test is configured with 75 kg), braking distance, ground friction, slope, ground flatness, etc. Electric vehicles also need regular maintenance like cars, and they also need to go to regular testing institutes for functional testing.

The activity ended quickly, but I still felt unsatisfied. Today's study is closely related to our lives, and I learned so much!

Painting: Tao Yuyin from Class 1, Grade 4, Hanjiangwan Campus, Chongren Road Primary School, Wuhan

(Source: Jimu News)

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