Electric Vehicle (EV) Circuit Safety Protection SETsafe | SETfuse Solutions and Products

This document introduces circuit safety protection solutions for electric vehicles (EVs), covering the following key areas:

| Power Battery Pack --- Active Protection 

| Thermal Management System --- Over-Temperature Protection 

| Battery Management System (BMS) --- Over-Voltage Protection 

| Start-Stop Battery --- Active Protection 

Overview

Electric Vehicles (EVs) are transportation vehicles powered by one or more electric motors, utilizing rechargeable batteries or other energy storage devices. EVs encompass Battery Electric Vehicles (BEVs), Plug-in Hybrid Electric Vehicles (PHEVs), and Fuel Cell Electric Vehicles (FCEVs), including electric bicycles, cars, trucks, and more. EVs are characterized by low emissions, energy efficiency, and sustainability, making them widely applicable in personal mobility, logistics, and public transportation.

Market Scale: According to market forecasts, the global EV market is expected to reach approximately USD 470 billion (around CNY 3.25 trillion) by 2025, with sales exceeding 21 million units. China is projected to contribute about 60% of global sales, with a new energy vehicle (NEV) penetration rate of 23.2%. By 2030, the global EV market is anticipated to surpass USD 1 trillion (approximately CNY 6.9 trillion), with sales reaching 70 million units and an NEV penetration rate approaching 60%. China will remain the dominant market, with the light EV and Battery Management System (BMS) markets expected to exceed USD 100 billion and USD 40 billion, respectively (data sourced from the internet, for reference only).

Why EV Batteries and Thermal Management Systems Require Circuit Safety Protection

Circuit safety protection is critical to address the following risks, ensuring battery safety, reliability, and user protection:

Thermal Runaway Risk 

Abnormal conditions such as overcharging, over-discharging, high temperatures, or short circuits may trigger thermal runaway, potentially causing battery fires or explosions. Thermal management systems monitor and regulate temperature to prevent heat buildup, ensuring batteries operate within safe temperature ranges.

Overcharge/Over-Discharge Damage 

Overcharging can lead to electrolyte decomposition, structural damage, or electrode material failure, while over-discharging may cause permanent capacity loss or battery failure. BMS manages voltage and current to prevent these issues, extending battery lifespan.

External Impact and Vibration 

EVs may experience collisions or vibrations during operation, which can cause internal short circuits or leakage. Safety protection mechanisms, such as mechanical safeguards and circuit isolation, mitigate these risks.

Battery Performance and Lifespan 

Safety protection optimizes battery performance through cell balancing, temperature control, and current management, extending lifespan, improving charging efficiency, and enhancing range.

User Safety 

Battery failures can result in fires, explosions, or electric shocks, endangering lives and property. Safety protection mechanisms, including real-time monitoring and rapid response (e.g., circuit disconnection), minimize accident risks.

Necessity of Thermal Management Systems 

Thermal management systems use sensors, thermistors, and control circuits to monitor battery temperature, combined with cooling or heating mechanisms (e.g., liquid cooling, air cooling) to regulate heat distribution. This prevents thermal runaway due to high temperatures or performance degradation in low temperatures, ensuring battery stability across diverse environments.

Certification Standards

Chinese National Standards (Mandatory) 

GB 38031-2025 

Applicable to EV power batteries, requiring no fire or explosion. 

New tests: Bottom impact, safety testing after fast-charge cycles, and revised thermal propagation tests. 

Emphasizes thermal management system reliability to prevent thermal runaway propagation. 

GB/T 31467.3-2015 

Targets lithium-ion batteries, covering over-temperature, over-voltage, over-current, and short-circuit tests. 

Requires BMS to have real-time monitoring and protection functions. 

GB 17761-2018 

Specifies electrical safety, overcharge protection, and thermal management requirements for electric bicycle batteries. 

Ensures battery safety under abnormal conditions. 

GB/T 36972-2018 

Defines requirements for over-temperature, over-voltage, over-current protection, and cycle life. 

Mandates effective temperature fluctuation control by thermal management systems. 

International Standards (Partially Mandatory, Depending on Market Requirements) 

IEC 62133 

Safety standard for secondary batteries in portable devices, applicable to lithium batteries. 

Tests include overcharge, over-discharge, short-circuit, and thermal abuse, ensuring thermal management system effectiveness. 

UN 38.3 

Mandatory lithium battery transportation safety standard for international shipping. 

Tests include vibration, impact, overcharge, and over-temperature, ensuring battery and thermal management system safety during transport. 

ISO 26262 

Automotive functional safety standard, applicable to EV BMS. 

Requires thermal management, over-temperature, and over-voltage protection to meet specific safety levels (e.g., ASIL C) for system reliability. 

UL 2271 

Safety standard for light EV batteries, covering electrical, mechanical, and environmental tests. 

Requires thermal management systems to remain stable under extreme conditions (e.g., high/low temperatures). 

EN 15194 

Mandatory European standard for electric bicycles (EU market). 

Requires BMS to include over-temperature, over-voltage, and short-circuit protection, ensuring thermal management system safety. 

Safety protection for EV batteries and their thermal management systems is critical to prevent risks such as thermal runaway, overcharge/over-discharge, and external impacts, ensuring performance, longevity, and user safety. These protections are typically achieved through intelligent BMS management and hardware components (e.g., fuses, TVS diodes, thermistors). Mandatory domestic and international standards (e.g., GB 38031-2025, IEC 62133, UN 38.3) impose stringent requirements on battery and thermal management system design, testing, and performance to ensure safety and compliance under various operating conditions.

SETsafe | SETfuse Solutions, Products

Protection Type: Power Battery Pack --- Active Protection 

Product Name: 

Pyrotechnic Cut-Off (PCO) 

Series: 

PHW  Learn more

PWX  Learn more

Protection Type: Thermal Management System --- Over-Temperature Protection 

Product Name: 

DC Thermal Cut-Off (DC-ATCO) 

Series: 

RSKxxxA  Learn more

ARL  Learn more

RQF  Learn more

TGxxxC  Learn more

Protection Type: Battery Management System (BMS) --Over-Voltage Protection 

Product Name: 

Transient Voltage Suppression Diode (TVS) Automotive Grade 

Series: 

SMD Type: ASMA  Learn more

SMD Type: ASMB  Learn more

SMD Type: ASMC  Learn more

SMD Type: SM8SxxA  Learn more

SMD Type: SM8TxxA  Learn more

Product Name: 

Electrostatic Discharge (ESD) TVS 

Series: 

SMD Type: GSM24CCAN  Learn more

Examples: 

Over-Voltage Protection for BMS Main Control Board Power Port 

ESD Protection for BMS Signal Port 

Over-Voltage Protection for BMS Analog Front-End (AFE) Power Port 

Protection Type: Start-Stop Battery --Active Protection 

Product Name: 

Intelligent Thermal Cut-Off (iTCO) 

Series: 

THUxxx-R  Learn more

Product Name: 

Pyrotechnic Cut-Off (PCO) 

Series: 

PHW  Learn more

PWX  Learn more

Commonly Used Circuit Protection Components for EV Circuit Safety (For Reference) 

Fuses 

MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) 

Thermistors (NTC/PTC) 

Relays 

Gas Discharge Tubes (GDT) 

Varistors 

Partner with SETsafe | SETfuse to Transform Technical Challenges into Reliable Solutions

When you encounter technical challenges in selecting circuit protection components or designing system solutions, the professional engineering team at SETsafe | SETfuse is your trusted partner. Specializing in over-temperature, over-current, over-voltage, and active protection technologies, SETsafe | SETfuse offers comprehensive technical expertise and rapid response to meet your needs. Whether you require precise product parameter guidance or comprehensive system-level protection solutions, SETsafe | SETfuse delivers professional, practical, and efficient recommendations and support.

From initial design consultation and solution implementation to post-sales product assurance, we provide end-to-end collaboration, ensuring your project progresses seamlessly and reliably. For any inquiries or requirements, please contact us at: sales@SETfuse.com

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