In electric vehicle on-board chargers (OBCs), DC bus capacitors typically range from 470μF to 2200μF. Without effective pre-charge protection, the large inrush current generated during startup can damage power semiconductors, relays, and other critical components. Repeated current surges may also accelerate battery aging by increasing internal resistance, ultimately reducing battery cycle life.
Compared with industrial applications, automotive environments place much stricter requirements on passive components. OBC systems must operate reliably under severe vibration, wide temperature ranges from -40°C to +125°C, and frequent charging cycles. Conventional industrial-grade pre-charge resistors often struggle to meet these long-term reliability demands.
Why Use Power NTC Thermistors in OBC Pre-Charge Circuits?
Power NTC thermistors offer several advantages for automotive pre-charge applications:
1. Superior Cold-Start Protection
At low temperatures, such as -40°C, NTC thermistors exhibit higher resistance, providing stronger inrush current suppression during vehicle cold starts.
2. Lower Power Loss at High Temperature
Once heated, the NTC resistance drops significantly, minimizing power dissipation and reducing heat generation inside the enclosed OBC environment.
3. High Reliability Under Harsh Conditions
Automotive-grade NTC thermistors are designed to withstand thermal cycling, mechanical vibration, and long-term operation while maintaining stable resistance characteristics.
At JEC (Dongguan Zhixu Electronics), we provide power NTC thermistors designed for high-reliability automotive and power electronics applications:
Model: MF72 10D-15
Maximum steady-state current: 5A
Suitable for large DC bus capacitors
Excellent thermal performance and surge capability
Designed for high-voltage platforms, including 800V EV architectures
Higher voltage ratings
Enhanced energy absorption capability
If you are designing OBC, DC/DC converter, energy storage, or high-power charging systems, contact JEC for free samples and one-on-one engineering support.
Post time: Jul-03-2026