Why High-Voltage Harnesses Need the Right Conductor
In a new energy vehicle, the power battery directly or indirectly provides the energy, the drive motor uses that power to drive the vehicle, and the electronic control system manages the power output. What connects these devices and lets each perform its function is the wiring harness installed in the vehicle. Unlike the harness in a traditional car, the new-energy-vehicle harness also includes a high-voltage harness - an essential component that safely and reliably transmits the electrical energy needed to drive the vehicle, playing a key role in the safety, reliability and stability of the vehicle.
Copper as the Standard Conductor
At this stage, automotive high-voltage wiring harnesses mainly use copper as the conductor (see QC/T 1037-2016), including bare round copper wire and tinned soft round copper wire, formed into stranded conductors.
1. Excellent Electrical Conductivity
At 20 °C, the resistivity of copper is 0.0185 Ω·mm²/m, compared with 0.0294 Ω·mm²/m for aluminum - copper conducts about 60% better.
Under high current, the working temperature rise is lower, reducing heat loss during transmission; the excellent thermal conductivity of copper also keeps the working temperature of the high-voltage harness within a safe range.
Because of the excellent conductivity, the cross-sectional area of the copper wire can be smaller under the same load - which helps flexible layout of the harness, including a smaller turning radius (high-voltage harnesses generally need a bend radius of more than 5–6 times the harness diameter).
Finer harnesses reduce bending stress and the force needed for installation, connector insertion and removal, lowering installation and maintenance difficulty; the smaller cross-section also lets the harness be arranged flexibly in grooves and corners of the metal body, or close to the body, effectively reducing electromagnetic interference.
2. Good Mechanical Properties
Besides conductivity, copper offers better tensile strength and bending properties than alternative conductors. Copper has a tensile strength of 200–240 MPa with elongation up to 50%; its good plasticity makes it easy to process by calendering, extruding and stretching into various shapes and sizes. In service, the copper conductor withstands the vibration and friction of vehicle travel, giving higher reliability and a longer service life.
3. Chemical Stability and Corrosion Resistance
Copper also has good chemical stability, corrosion resistance and easy weldability. Vehicle operating environments are complex and harsh: high-voltage harnesses and terminal connectors inevitably work in humid, salt-spray and other corrosive environments. In humid, high-temperature and vibration conditions, conventional harnesses suffer insulator wear, loose joints and wire corrosion, which leads to disconnection or short-circuit failures. Since high-voltage harnesses carry higher voltages and currents and place greater stress on terminals and connectors, safety requirements are higher: quality copper ensures terminals and connectors maintain good contact over the long term, avoids galvanic corrosion, and slows insulation aging or damage and conductor corrosion. These are among the main challenges that alternative materials must fully verify before they can replace copper as a high-voltage harness conductor.
Summary
Copper's combination of high conductivity, good mechanical strength, excellent corrosion resistance and easy termination makes it the reliable choice for high-voltage wire harnesses in new energy vehicles - where safety, reliability and stability are non-negotiable.
