From E-Motor EOL, ECU Thermal Aging to Battery Pack Testing — Re-examining Connection Design for High-Voltage, Signal and Fluid Circuits

Within the new energy vehicle manufacturing industry, it is widely acknowledged that testing of the three-electric system (battery, motor, electronic control unit) acts as a critical threshold determining overall vehicle quality. Unlike conventional powertrain systems, three-electric testing represents highly coupled complex engineering integrating high-power electricity, control signals, thermal management and safety protocols. However, one process segment is frequently underestimated yet directly restricts production takt and operational reliability: the physical connection between test equipment and the Device Under Test (DUT).

Engineers specializing in three-electric testing will readily relate to this challenge. Whether conducting end-of-line (EOL) testing for electric drive systems, constant-temperature aging of ECU assemblies, or final testing of battery packs, frequent connections and disconnections of high-voltage circuits, low-voltage signal harnesses and coolant pipelines are mandatory. With withstand voltages reaching thousands of volts and peak currents hitting hundreds of amperes, compounded by high-temperature aging environments, manual plugging and unplugging of each harness and pipeline is not only time-consuming and labor-intensive, but also carries significant risks of misconnection and fluid leakage.

Test Preparation Is Essentially Building Complex Transmission Channels

On a typical battery Pack EOL test line, workpieces pass through successive stations for air tightness, electrical safety, reliability and performance testing. If operators must manually disconnect and reattach all circuits at every station, test preparation time becomes excessively prolonged, rendering full automation meaningless.

Calculating Capacity Logic Behind "Integrated Single-Plate Design"

This is the exact application scenario for Qiaotian Intelligent’s ECS (Energy Combination System) modular connection solution. Simply put, standardized docking plates are installed on both the pallet side and equipment side, integrating all required high-voltage, low-voltage and fluid modules. As the pallet carrying DUTs enters the test chamber, driving actuators drive the connectors on both sides to complete precise automatic docking in a single motion.

This integrated single-plate design eliminates cumbersome wiring procedures and, more importantly, unlocks production line flexibility. With customized transition harnesses, a single test line can accommodate multiple product variants, realizing true multi-model compatibility on one production line.

Technical Core Enabling Stable Operation Under Harsh Working Conditions

Battery test environments impose extreme strain on connectors. Qiaotian’s ECS system delivers reliable performance under such rigorous conditions, supported by four core technical strengths:

1. Floating & Position Correction Mechanism

   Mechanical positioning deviations between pallets and test chambers are inevitable on automated lines. The ECS system is equipped with diamond and cylindrical pin guiding structures, offering floating compensation of ±2 mm along the X/Y axes, ±1 mm along the Z axis, and ±0.5° angular offset. This absorbs manufacturing and docking tolerances to guarantee stable equipment operation.
2. Ultra-Low Contact Resistance Under High-Frequency Mating Cycles
4. Test line connectors undergo countless mating cycles daily. Qiaotian’s QCM electrical modules adopt lamella finger contact technology, delivering ultra-low contact resistance and maintaining cool operating temperatures under heavy current overloads. Their service life exceeds 100,000 mating cycles, far outperforming standard connectors.
6. Flat-Face Dry Break Fluid Design

   Circuits carrying water or oil face severe safety hazards from medium leakage during disconnection, especially in high-voltage test environments. Qiaotian’s fluid modules adopt flat-face dry-break architecture to prevent fluid dripping at the interface upon separation, establishing a fundamental barrier for electrical safety.

Real-World Field Application: Battery Pack Test Line of A Leading Manufacturer

Take a practical project for reference. For a customer’s battery Pack test line, stringent technical specifications were specified: rated 600 A energization for 40 seconds; shielded twisted low-voltage signal cables rated at 5 A; 3500 V dielectric withstand test; compatibility with 10 product models.

Similar high-voltage challenges are prevalent in ECU thermal aging testing. In another project, equipment inside an 85 °C constant-temperature aging chamber needed to withstand 4000 V HIPOT voltage and rated 400 A / peak 600 A current, while supporting 135-pin low-voltage signal transmission and a 35 L/min fluid circuit. Customized ECS module configurations allowed Qiaotian to fully satisfy these extreme operating conditions.

Efficiency Gains Go Beyond Superficial Numerical Improvements

• Manual plugging, verification and locking operations that once took several minutes are condensed into a few seconds of automatic docking;

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• Hazards of misplugging or missing connections are eliminated, lowering risks of distorted test data and equipment damage;
• Most critically, standardized interfaces drastically simplify model changeovers — new products can be tested simply by swapping pallet-side transition tooling, delivering tangible improvements to equipment OEE (Overall Equipment Effectiveness).

As three-electric technology iterations accelerate, testing priorities have shifted from individual component performance verification to systematic coordination and mass-production reliability validation. Under this trend, test data accuracy and line throughput heavily rely on the stability of these "invisible" physical connections.