special report

How safe are electric vehicles using high-voltage batteries?

The high-voltage batteries used in electric vehicles today offer maximum safety and longevity. If you are still hesitating about switching from a fuel-powered car to an electric vehicle (EV) because you are worried about the safety of the battery, don’t worry! According to multiple media reports, many people are very concerned about the dangers of electric vehicles and their high-voltage batteries. In fact, high-voltage batteries are very safe to use under normal operating conditions, and there are relatively few problems. In fact, the high-voltage battery in an electric car is just like the battery in an electronic clock, simple, reliable and safe.

In contrast, batteries in internal combustion engines (ICEs) are used primarily to start the engine and power auxiliary functions such as air conditioning or music systems, while batteries in electric vehicles can basically power everything from the engine to the on-board computer to power windows. power supply to the components.

High-voltage batteries account for a large portion of the total vehicle cost, equivalent to 30% to 40% of the total price of a new electric vehicle. Given the price, you also want to be sure that your high-voltage battery will operate safely and efficiently for as long as possible.

Considering their importance, the industry has conducted rigorous scrutiny on high-voltage batteries (HV Batteries), and governments around the world have also adopted strict regulatory measures by setting safety standards, collaborating on research, and investigating recalls or other safety-related issues.

The lithium-ion high-voltage batteries currently used most in electric vehicles are equipped with high-voltage contactors, which can safely and effectively disconnect the current under normal operating conditions.

temperature fluctuations

Today, the performance of electric vehicles is comparable to that of internal combustion engine vehicles, but temperature management is critical to ensuring that electric vehicles operate safely and at maximum efficiency. The ideal operating temperature of electric vehicle batteries is about 70℉ (21.5℃), while the normal operating temperature range is 5℉-113℉ (-15℃-45℃). Temperatures outside this range, especially at lower temperatures, may result in significant performance degradation.

Possibility of short circuit

In addition to this, it is also important to keep your electric vehicle in good repair condition. If there is any damage, repair it immediately to avoid external short circuits. Short circuits are dangerous and may cause irreparable damage.

Safety disconnect device for maintenance or first aid personnel

Once an emergency occurs, immediate response from fire or public security emergency personnel is required. All electric vehicles are equipped with emergency shut-off or disconnect devices, and emergency personnel have received relevant training in their use. In addition, when the electric vehicle is turned off at night or in a parking garage, the high-voltage contactor automatically disconnects the high-voltage battery.

Whether charging at home or at a charging station, access to safe and convenient power has always been a major advantage of driving an electric vehicle. It is expected that by 2030, the number of charging stations will increase to more than 2.1 million Level 2 public charging piles.

Ultra-high voltage fast charging solutions or DC fast charging (DCFC) are also expected to increase, although currently only a small number of charging piles are equipped with this solution.

In 2019, with the advent of 800V batteries (battery capacity doubled compared to 400V standard engine batteries), car manufacturers began to build high-power vehicles that are lighter, charge faster, and are safer. In fact, it takes just over 20 minutes to charge an 800V engine battery to reach 80% capacity, while a 400V standard battery takes 40 minutes to reach the same capacity.

However, 800V high-voltage batteries are currently used in only a few vehicles. However, as more mainstream car companies continue to improve their manufacturing technology, this number will continue to increase.

“High-voltage contactors have been specially installed in the system to disconnect high loads in emergency situations. We have used an ultra-compact design and utilize our gas-filled ceramic arc chamber to safely disconnect power quickly and reliably throughout its service life ”

— Claas Rosenköetter, TDK Electronics, a TDK Group company

As an industry-leading manufacturer, TDK has launched a series of high-voltage contactors to meet the needs of high-current DC contactor relay applications. HVCs (High Voltage Contactors) are not only critical for electric vehicles, they are also an integral part of charging stations, commercial vehicles such as buses, trucks and heavy equipment, uninterruptible power supplies and renewable energy storage systems .

How to improve the safety of high-voltage contactors

TDK considers safety when designing high-voltage contactors. As an integral part of the battery disconnect unit (BDU)*1 of electric vehicles, the high-voltage DC contactor is part of the system used to disconnect the battery and extinguish the arc generated in the contactor during an emergency or malfunction. Such failures may include battery issues, mechanical problems, or damage caused by external factors.

By expanding the product portfolio of high-voltage DC contactors, TDK has developed a new smaller HVC43 series, which is 30% lighter than the previous model. The inflatable ceramic arc chamber is suitable for small current designs below 250A and can quickly disconnect and extinguish the high loads currently found in electric vehicles.

Why is disconnecting so important?

The high-voltage relay contactor is an important component of the vehicle's electrical safety system and is an important component in the vehicle's BDU controlled by the battery management system*2 (BMS). In the event of a malfunction, the BDU must disconnect the lithium-ion battery to avoid battery damage. In severe cases, it may cause fire or even explosion.

In electric vehicles, when high-power electrical equipment switches between on and off states, an arc is generated between the two contacts of the switch. In hazardous situations, this arc can be very destructive if not extinguished.

As electric vehicles gain market share across the auto industry, many leading experts are also ramping up their economic forecasts. According to Bloomberg, with the passage of the Inflation Reduction Act of 2022, electric vehicle sales are expected to account for 52% of the overall U.S. market by 2030. Even more radically, the EU has also passed an agreement that requires a ban on the production of all new non-electric vehicles after 2035.

As more consumers choose electric vehicles, the media will report less on the rare safety issues that arise in special circumstances, which will further drive the shift to an environment without internal combustion engines. After the high-voltage DC contactor is installed in the high-voltage battery system, the safety of the vehicle will be further improved, power supply will be realized on demand, and the charging speed will be faster.

in conclusion

TDK will continue to work on developing technologies that can improve the safety of high-voltage batteries and quickly launched the industry's first high-voltage DC contactor design to improve short-circuit performance.

Nowadays, car users no longer need to worry about safety and convenience, and can choose vehicles based on their own values. This means drivers get the same safety and performance experience as traditional gasoline-powered cars while also helping to improve the environment, which is a win-win situation for everyone!