Issue link: https://iconnect007.uberflip.com/i/1542458
JANUARY 2026 I SMT007 MAGAZINE 55 Standards for PTC heater power cycling, connec- tor lifecycle testing, or EMI emissions for HV pumps are less developed. This gap limits design reuse and complicates supplier qualification. The result is often redundant testing and uncertainty around expected service life, especially for newer compo- nents. The path forward lies in collaborative standards development. Organizations like the Global Elec- tronics Association are building awareness to address auxiliary subsystem requirements with the same rigor as with other harsh environment indus- tries. Common testing regimes, vibration-resis- tance benchmarks, and qualification protocols will increase reliability and reduce redundant costs. Future guidelines will need to account for mixed- voltage zones, such as 12V/48V/HV hybrids, field failure modes related to harsh environments, and test coverage gaps in qualification protocols. Part- nerships among automotive OEMs, Tier-1 suppli- ers, reliability labs, and standards consortia will be necessary to define test methodologies and qual- ity metrics, given the increasing number of auxiliary modules entering service each year. Conclusion HV auxiliaries are mission-critical, not optional. They are dispersed, harsh-environment-exposed systems requiring DFR from the ground up. Mois- ture ingress, vibration damage, thermal cycling, and inadequate clearances are common failure modes. Auxiliary module integration and connector reliabil- ity deserve as much attention as inverters or battery packs. Designing for reliability at the auxiliary level is an essential step toward delivering sustainable, high-performance EVs that meet consumer expec- tations, regardless of weather, usage, or terrain. SMT007 Stanton Rak is principal consultant for SF Rak Com- pany, and co-chair of the APEX EXPO Technical Com- mittee. References 1. "EV Auxiliary Systems," ON Semiconductor. 2. "How to Design Heating and Cooling Systems for HEV/ EVs," by A. T. Vemuri, Texas Instruments, 2020. 3. "11 Most Important High Voltage Components of Electric Vehicles," by Guchen Connector Blog, Guchen Connector, March 14, 2023. 4. "Recall 23V-518: Jaguar I-PACE HV Heater Module Isola- tion Fault," by National Highway Traffic Safety Administra- tion (NHTSA), NHTSA, January 22, 2023. 5. "Field Service Bulletin N212356540: Chevrolet Bolt HV Busbar Terminal Corrosion Update," GM Service Connect, 2021. 6. "NHTSA Opens Ford Mustang Mach-E Investigation Over Recall," by E. Snitkoff, Ford Authority, Aug. 21, 2023. 7. "A Unified Thermal Management Framework for Elec- tric Vehicles: Design and Test Bench Implementation," by M. Narimani, S.A. Emami, A. Banazadeh, and A. Modar- resi, Applied Thermal Engineering, 2024. 8. "Research on Thermal Management System Integration of Electric Vehicles," by Y. Yuan and G. Liu, Journal of Applied Mathematics and Physics, 2024. 9. "Electric Vehicle Air Conditioning System and Its Influ- ence on Range and Energy Consumption," by S. S. Jose et al., World Electric Vehicle Journal, 2022. 10. "Design Considerations for Automotive PTC Heater Mod- ules (SLUAAY5)," by Texas Instruments, Texas Instruments, 2024. 11. "Heater Not Working Thread (Model 3 PTC Issues)," Tesla Motors Club, 2020. 12. "Automotive e-Compressor – High-Voltage EV Thermal Management," Infineon Technologies, 2025. 13. "ISO 17409: Electrically Propelled Road Vehicles—Con- nection to External Electric Power Supply—Safety Require- ments," ISO, 2020. 14. "High-Voltage System: Isolation Faults Due to Possible Moisture in Heater Plug or HV Cable," NHTSA Technical Service Bulletin Database, 2018. 15. "EMC Issues in HV Auxiliary Systems for Electric Vehi- cles," by J. Spies, Automotive EMC Conference Proceed- ings, 2018. 16. "Thermal Performance Benchmarking of Automotive Power Electronics and Electric Motor Thermal Manage- ment Systems," by X. Feng, K. Bennion, and G. Moreno, 2016. 17. "ISO 6469-3: Safety for Electric Road Vehicles," by A. Schirn, ANSI Blog, Feb. 13, 2023. 18. "What Tests Do EV High-Voltage Wiring Harnesses Need to Do?" Guchen Connector, Feb. 12, 2025. 19. "IEC 60664-1: Insulation Coordination for Equipment Within Low-Voltage Systems," by International Electrotech- nical Commission, IEC, 2020 (amended 2025). 20. "Electric Bus Product Portfolio—Designed for High-Altitude Environments," CRRC, 2023. 21. "The Importance of Reliable Charging Station Electron- ics for Building a Sustainable EV Ecosystem: 'R' YOU READY?" EV Quality and Reliability Group, Global Electron- ics Association, July 2025.