At first glance, it’s hard to tell the difference between an electric vehicle and one powered by an internal combustion engine (ICE). Both look similar and move drivers from point A to point B.
Their biggest difference lies in how they’re powered — one relies on fuel, the other on stored electrical energy. Yet they share a common need: accurate temperature monitoring.
Like an ICE vehicle, excessive heat – or in more extreme cases, overheating – can affect an EV’s performance, safety, and lifespan. In electric vehicles, temperature sensor placement takes on even greater importance, as many components operate best within narrow temperature ranges.
A transportation technology defined by precision, an EV depends on well-placed temperature sensors that provide accurate control, provide early warning of issues, and help keep every system functioning as intended.
Temperature Sensor Placement: 7 Critical Areas in EV Design
Car temperature sensors are a key component of EV design -- on par with those that monitor battery power. When it comes to monitoring temperatures throughout the vehicle, there are seven places where sensors are a necessity:
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Motor
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Battery
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Inverter
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Charger handle, port, and high voltage connectors
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Thermal management system
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Passenger cabin
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Ambient aire
1. Motor
While substantially different from internal combustion engines (ICE), electric motors in hybrids and EV’s do require temperature control for optimum performance and life. Overheating electric motors can cause them to degrade or even fail before their expected life span.
Like an ICE engine, an EV motor needs to be kept within a certain temperature range to run efficiently. Going beyond that range in an EV causes overheating, during which the engine may run inefficiently or enter safe mode.
Install electric vehicle temperature sensors to monitor:
- Electric motor oil temperature
- Electric motor winding temperature
- Electric motor coolant temperature
Electric motor temperature control isn’t strictly about keeping temperatures down. In colder climates, electric motors can also be warned up through the heat pump system to provide peak performance.
2. Battery
The heart of an electric car is its battery. Without it, travel is impossible.
During operation and recharging, electric car battery temperatures rise, usually between 45-55 ℃. Excessive heat beyond a battery’s comfort zone of 10-45 ℃ has negative effects on battery aging.
Additional heat stress on the battery may:
- Shorten its lifespan
- Reduce its charging capacity
- Start thermal runaway
Like an EV’s motor, cold weather also impacts electric car battery performance. Temperatures lower than 10 ℃ make it difficult for the battery to:
- Hold a charge
- Maintain range
- Power efficiently
3. Inverter
As the channel through which DC energy is converted to AC to power the motor, inverters control the lifeblood of an electric vehicle. A byproduct of that conversion of current is heat, which when unchecked, can far exceed the optimal temperature limit of 150 ℃. When exposed to excessive heat for too long, the interior components start to fail and the device won’t function properly.
Common effects of overheating on inverters include:
- Insulation degradation
- Solder cracking
- Metal warping
4. Charger Handle & Port
As the source of an EV’s power, the EV charger’s handle and charging port can overheat too. High temperatures are indicative of a few issues:
- Poor connection
- Mechanical damage
- Charger malfunction
- Insulation failure
- Contamination
Monitoring temperatures of an EV’s charging handle and its port will become increasingly important as fast DC charging technology evolves.Though fast-charge technology has brought re-energizing times down to ~30 minutes for 80% power, consumers are seeking a refueling experience similar to filling a gas tank today.
Fast charging requires converting a large amount of power, which generates a large amount of heat. As the technology improves for quicker recharging times, monitoring temperatures helps ensure the process is safe and efficient.
5. Thermal Management System
While the base function of a thermal management system is to regulate an EV’s mechanical components and battery, the system itself needs monitoring too.
A thermal management system’s temperatures directly impact the EV components it’s supposed to cool. When its temperatures spike beyond normal ranges, a domino effect may happen, causing many of the same issues previously listed. Critical information to system controllers to optimize performance and minimize power consumption while maintaining appropriate system temperatures with temperature sensors monitoring critical points in both coolant and refrigerant systems.
High temperatures within a thermal management system are a sure sign that something’s wrong, be it a malfunction inside the system -- such as a leak -- or a failure in one of the components it’s cooling.
6. Passenger Cabin
A vehicle that’s too hot or cold makes for a long, uncomfortable ride. Besides its motor, an electric vehicle’s HVAC system is the next-most noticeable thing running while an EV is on.
The cornerstone of an electric vehicle’s functionality is efficiency -- or making sure it uses no more power than absolutely necessary. Electric vehicle sensors tell the car and computer exactly how hard the vehicle’s systems need to work.
With in-cabin electric vehicle HVAC system temperature sensors, drivers and passengers stay comfortable without draining the battery too quickly and reducing its range. These sensors sample the average air temperature in the cabin as well as the duct air and evaporator temperatures to maintain a comfortable temperature regardless of the outside while minimizing the power consumed in heating and cooling the cabin.
7. Ambient Air
Exterior temperature sensors aren’t about giving drivers and passengers an idea of the climate they’re stepping into.
Like an in-cabin HVAC temperature sensor, an external device tells the vehicle how hard some of its other systems, such as the thermal management system, have to work to overcome environmental temperatures. Outside temperature sensors are typically installed in the side mirror or in the front fascia of the vehicle and provide critical information to the sophisticated algorithms to manage vehicle performance. These systems need to understand ambient temperature to properly manage the multiple heat exchangers, pumps, and compressor systems in the vehicle.
FAQ: Temperature Sensor Placement in Electric VehiclesThese answers address some of the most common questions about temperature sensor placement and performance in electric vehicle design. Q: How is temperature sensor placement determined during EV design?A: Placement is determined through thermal modeling and simulation during the early stages of design. Engineers study how heat moves through the motor, inverter, and battery pack to identify areas that need close monitoring. After modeling, prototype testing validates those locations in real-world conditions. The goal is to capture accurate temperature data where it matters most while keeping sensors out of the way of other systems. Q: What types of temperature sensors are used in each EV system?A: Each EV system uses sensors suited to its environment. NTC thermistors work well in battery packs and cabin systems because they respond quickly within moderate temperature ranges. RTDs are often used in motors and inverters for their long-term stability and precision. Thermocouples handle rapid temperature changes in harsh areas such as charger handles or connectors. Some newer EVs use digital temperature sensors for better data accuracy and communication with control systems. Q: How does sensor data integrate with the EV’s control systems?A: Temperature data flows from each sensor to the vehicle’s ECU or thermal management controller. These systems compare readings to safe operating limits and adjust cooling or power as needed. In many EVs, a network of sensors shares data in real time. This helps the control software manage heat across all components at once, improving efficiency and extending system life. |
Why Temperature Sensor Placement Matters in Electric Vehicle Design
No matter the fuel source, temperature sensors have long been part of vehicle design.
In electric vehicles, though, their influence depends on accurate temperature sensor placement throughout the system. When sensors are positioned effectively, they help maintain performance and safety by keeping components within their ideal operating range.
With reliable temperature management in place, EVs continue to deliver the efficiency and driving experience that make them an appealing alternative to traditional combustion vehicles.
Go Deeper into EV Sensor Design
The Amphenol EV/HEV Resource Hub offers guidance and data to help you refine sensor placement and temperature management in your projects.
This article was originally published in December of 2021 and was recently updated to reflect current industry trends.
