Temperature sensors: safeguarding EV battery packs

Why temperature matters 

Most of today’s electric vehicles use lithium-ion batteries, which have an ideal operating temperature range of typically around 25°C (77°F). When temperatures deviate from this, the battery’s capacity, charging speed and discharge efficiency may suffer. In addition, overheating of batteries can lead to thermal runaway resulting in the battery catching fire or even exploding. Temperature sensors, such as NTC thermistors, are crucial in preventing such incidents by monitoring and alerting when the battery temperature exceeds safe limits. 

Placed directly inside the battery cells, internal sensors provide precise temperature readings, ensuring that each cell operates within a safe range by controlling heating and cooling mechanisms. Continuous monitoring allows for the assessment of battery health and can trigger safety measures in the event of overheating, such as disconnecting the battery or reducing charging rates.

High-voltage battery solutions 

The trend towards higher-voltage EVs continues as drivers seek ever-better performance. They offer a number of key advantages including: 

• Improved range: high-voltage batteries typically have higher energy densities which translates into longer driving ranges between charges.
• Faster charging: these systems can handle higher charging power levels, which leads to faster charging times. 
• Enhanced performance: by providing the necessary power to achieve better acceleration and higher top speeds, high-voltage batteries contribute to the responsive performance some EVs are known for.
• Regenerative braking: high-voltage systems are often used in regenerative braking systems which convert kinetic energy back into electrical energy during braking. This can be stored in the battery and used to extend the vehicle’s range or improve efficiency.
• Efficiency: by operating at higher voltage levels, these systems reduce current flow and minimise resistive losses in electrical components, improving the overall efficiency of the powertrain.

Specifying temperature sensors for high-voltage EV batteries 

High-voltage systems are versatile and can be adapted for various vehicle types including passenger cars, trucks, buses and even industrial applications. To ensure the safety, performance and longevity of the battery, specialised engineering is required. Factors to consider include the location of the sensor and whether it is inside or directly on each battery cell; the required accuracy and resolution; the response time of the sensor; how the sensor is integrated into the battery cell; environmental considerations including vibration and humidity, and compliance with relevant industry standards.

NTC thermistors for EV battery cells can be customised to suit the specific needs of the EV manufacturer. Examples include the use of flexible elastic housing which fits around the outside diameter of the battery cell and can be customised to accommodate varying cell sizes. 

If you are uncertain about the specific temperature sensor requirements for your EV battery cells, talk to our team of experts who have specialist knowledge of battery cell monitoring applications. They will work with you to design and manufacture a sensor that meets your performance and safety requirements.