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Why are tinned copper wires, aluminum wires, and aluminum rows the development trend of new energy vehicle wiring harness materials in the future?

May 07, 2024

According to public data, my country's annual production and sales of new energy vehicles have increased from 75,000 vehicles ten years ago to 9.5 million vehicles, accounting for more than 60% of the world, with an average annual compound growth rate of 71%. At present, the domestic new energy vehicle industry is entering a period of accelerated development, and achievements in the fields of new energy vehicles and power batteries are also rapidly spreading. Consumers' favor for new energy vehicles stems not only from environmental awareness and the pursuit of low-carbon travel methods, but also from the pursuit of more efficient forms of energy conversion. Compared with traditional fuel vehicles, new energy vehicles have advantages in environmental protection and intelligence, but the biggest advantage lies in energy conversion efficiency.

The energy conversion efficiency of the internal combustion engine of a fuel vehicle is usually between 20% and 30%, and the remaining energy is lost in the form of waste heat. The energy conversion efficiency of new energy vehicles can reach 80%-90%. Whether it is pure electric or plug-in hybrid, the energy conversion efficiency is much higher than that of fuel vehicles. As more efficient power units in new energy vehicles gradually replace inefficient power units, energy efficiency will be further improved. The rise of new energy vehicles not only represents the green transformation of transportation methods, but also indicates the direction of efficient energy use in the future.

According to research by domestic and foreign scholars, the energy conversion efficiency of new energy vehicles is also significantly affected by factors such as battery performance and motor efficiency, vehicle body weight, and energy conversion loss during charging and discharging. These losses directly limit the further improvement of energy conversion efficiency.

Judging from the current technological development trends, optimizing the materials and connection methods of conductive lines in new energy vehicles is the best way to improve energy conversion efficiency.

Traditional automobile wires have always used copper as the conductor material. However, copper wires also have some drawbacks: for example, they are prone to patina formed due to oxidation. It not only makes the appearance of the wire worse, but more importantly, its electrical conductivity is far inferior to that of pure copper. Therefore, the resistance in the circuit will be significantly increased and the current transmission efficiency will be reduced, which may affect the performance and safety of new energy vehicles.

In order to solve the problem of copper wires being easily oxidized, a common solution is to use tinned copper wires. The tin layer can effectively prevent copper from contacting oxygen and water in the air, thereby slowing down the oxidation process of copper. At the same time, tinned copper wire has good electrical conductivity and mechanical properties. These characteristics determine its application value in the field of new energy vehicles.

However, due to the low melting point of the tin layer, when welding tinned copper wires with ultrasonic wire harness welding, local high temperatures may cause the tin layer to melt, affecting the welding effect. Therefore, during the ultrasonic welding process of tinned copper wire, how to accurately control the welding temperature and time is a very difficult technical difficulty to overcome.

However, it should be noted that tinned copper wire is relatively expensive to produce. This limits its wide application in the field of new energy vehicles to a certain extent. Currently only used in high-end new energy vehicles. China needs to import a large amount of copper materials every year, and the price of copper materials has continued to rise in recent years. The scarcity of copper resources and rising prices have kept the cost of automotive wires high.

Can we improve energy conversion efficiency while reducing production costs? In the industry, aluminum wires are regarded as a viable substitute for copper wires. Major new energy vehicle manufacturers have already tried to use aluminum wires to replace copper wires because aluminum wires have the following advantages in new energy vehicles:

1. Good electrical conductivity:

The resistivity of aluminum is 2.65×10-8 Ω·m, while the resistivity of copper is 1.72×10-8Ω·m. Although aluminum has a higher resistivity than copper, the resistance requirements of the entire vehicle circuit can be met by increasing the wire diameter of the aluminum wire (about 1.3 times).

2. Lightweight:

The density of aluminum is 2.7g/cm³, while the density of copper is 8.96g/cm³. The density of aluminum is only one-third that of copper, so weight reduction can be achieved by simply increasing the cross-sectional area of the aluminum conductor by approximately 30%.


3. Cost-effectiveness:

Due to the extreme imbalance in my country's copper and aluminum mineral resources and their mining costs, the price of copper wires is much higher than that of aluminum wires. By using aluminum wires instead of copper wires, we can reduce the production cost of new energy vehicles and make them more competitive in the market.


In the field of automotive wiring harnesses, cost and weight are also one of the key reasons for the development of lightweight automotive wiring harnesses. Using aluminum conductors instead of traditional copper conductors does have the advantage of reducing cost and weight. However, there are also some technical difficulties in the application of aluminum conductors, such as:

1. Connection reliability:

Problems such as metal oxidation and electrochemical corrosion that may occur during traditional crimping of aluminum conductors and copper conductors will cause loose connection points or increased resistance, affecting the performance of the entire conductor.

2. Creep effect:

Creep is a phenomenon of slow deformation of metal materials under the action of external force for a long time. Due to the difference in thermal expansion coefficients between copper and aluminum, aluminum wire is more prone to creep. Under certain conditions, the creep rate of aluminum wires can be as high as 25 times that of copper wires, which has a significant impact on the fatigue resistance and service life of aluminum conductors.

3. Increase in wire volume:

The conductivity of aluminum wires is weak. In order to meet the conductive requirements of automobile wires, the cross-sectional area of the aluminum wires needs to be increased, which will increase the volume of the wires to a certain extent and bring greater challenges to connections.


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