Today’s technology allows electric cars to use thermal energy more efficiently and control it more effectively. Batteries, HVAC systems, electric motors, and inverters all contribute to temperature control. A Battery Thermal Management System (BTMS) is used to accomplish this.
To maximize energy efficiency, heat can be redirected into the cabin or battery when the motor heats up.
Let’s discuss the following topics to better understand electric vehicle battery manufacturing challenges and solutions:
- EV Battery Cooling Methods
- Why EV Batteries Need to Be Cooled
- Thermal Management Challenges
EV Battery Cooling Methods
Air cooling or liquid cooling can be used to cool EV batteries. Modern cooling requirements are met by liquid cooling. To understand the differences between the two methods, let’s examine them both.
Air Cooling
In both passive and active forms, air cooling cools the battery.
The battery is cooled or heated by passive air cooling, which uses outside or cabin air. It is usually limited to a few hundred watts of heat dissipation.
Active air cooling is powered by an air conditioner, which includes an evaporator and a heater for controlling the temperature of the air. The cabin can be cooled or heated with this device. However, its cooling capacity is usually limited to 1kW.
Compared to passive cooling, active cooling provides better performance, including propulsion and charging. Additionally, it is more efficient at removing heat from batteries, but it requires more energy to maintain battery temperatures. In contrast to passive cooling, active cooling involves using external devices or systems to cool the battery, such as fans, heat sinks, and cooling fluids (if liquid cooling is used). Passive cooling does not require any external systems to operate.
Liquid Cooling
In terms of cooling technology, liquid cooling is the most popular. The battery is cooled with a liquid coolant such as water, a refrigerant, or ethylene glycol. Heat is transferred to another location by tubes, cold plates, or other components surrounding the cells. Cells and liquid coolant do not come into direct contact because components carrying the liquid prevent direct electrical contact.
Since liquid cooling uses pumps, fans, and other devices to actively extract and redirect heat, it is an active cooling method.
A direct-contact medium, such as oil or dielectric liquid, can be used in some thermal management systems. Typically, these cells are used in non-consumer EVs because they are less safe and provide less effective insulation.
Cooling Methods Over Time
Currently, most batteries are liquid cooled with active cooling so that the temperature can be controlled better. Since liquids conduct heat better than air-hundreds of times better-temperature management is made easier.
Manufacturers were doing everything they could to minimize production costs at the beginning of the EV revolution, which made passive air cooling more appealing. Over the last decade, battery costs have dropped, and quick charging, which has more cooling requirements, has become more popular. Passive air-cooling has lost popularity as a result.
A Nissan Leaf with air cooling and a longer-range battery was about the same price as a Chevy Volt with active liquid cooling but a shorter range yet more powerful battery at the beginning of the 2010s. The cost of an active cooled high range, powerful battery would have been prohibitive at that time.
Active cooling is more expensive because it includes more components, such as a heat pump, a heat exchanger, a circulating pump, valves, and multiple temperature sensors. It is, however, much more reliable when it comes to cooling results.
Comparison of these three methods
A temperature range and uniformity can be achieved with each of these proposed systems. In order to achieve energy efficiency, the cooling effect must be greater than the heat generated by the cooling system. As the car outputs power, a system with too much additional weight will drain energy from it.
Despite being just as easy to implement and maintain as liquid cooling, phase change materials, fan cooling, and air cooling fail to meet the energy efficiency and size and weight requirements. Among the remaining cooling options, liquid cooling is the only one that does not consume too much parasitic power, delivers cooling requirements, and fits in the battery pack compactly and easily.
All Teslas, BMWs, Chevrolet Volts, Ford Focuses, Jaguars, and LG Chem’s lithium-ion batteries use some form of liquid cooling system. Using a liquid cooling system has been problematic in extreme temperatures since electric vehicles are still a relatively new technology. These are likely due to manufacturing problems, and as companies gain experience developing these systems, the thermal management issues should be resolved.
Why EV Batteries Need to Be Cooled
Battery performance and life depend on specific operating ranges for EV batteries. Temperatures between 68°F and 77°F (20°C and 25°C) are suitable for operation. The performance and life of batteries can be improved by better control of their temperature.
- Temperatures between -22°F and 140°F (-30°C and 50°C) can be tolerated during operation.
- It is possible for them to withstand temperatures between 32°F and 122°F (0°C and 50°C) during recharge.
The temperature of batteries must be kept within operating ranges as batteries generate a lot of heat during operation. High temperatures (158°F to 212°F or 70°C to 100°C) can cause thermal runaways, which destroy battery packs.
Battery cooling is necessary during fast charging. In order to maintain the high charging rate and not overheat the battery, excess heat must be extracted from the battery because of the high current flowing into the battery.
In some cases, they also need to be heated up when the temperature is too low or to boost their performance. It is not possible to charge cells below 32°F (0°C), for instance. Alternatively, Tesla offers battery preheating in some models to accelerate from 0 to 60 mph in less than two seconds.
Batteries for electric vehicles have been improved so that they can deliver more power and require less frequent charging. A cooling system that is effective remains one of the biggest challenges for battery safety.
Heat is generated by discharging the battery in electric cars. Heat is generated by batteries discharged rapidly.
Voltage differential is the basis of battery operation. When the battery reaches a high temperature, the electrons inside become excited, decreasing the voltage difference between the two sides.
different internal temperatures can cause different charge and discharge rates for each cell, determining both accuracy and battery life.
If the battery overheats or if temperature distribution is not uniform within the battery pack, potential thermal stability issues can occur, such as capacity degradation, thermal runaway, and fire explosion. Battery cooling systems are constantly being improved in the electric vehicle industry because of life-threatening safety concerns.
Thermal Management Challenges
EV batteries are commonly challenged by leaks, corrosion, clogging, temperature, and aging. The challenge of liquid cooling systems is different from that of air cooling systems, as you will see.
- As batteries age, their pipe connections are more likely to leak, which can cause leaks in liquid cooling systems. Battery performance and life will rapidly degrade if there are any leaks. The battery’s electrical insulation can even be damaged by humidity, causing the EV to stop operating. There must be no damage to the battery modules, interconnections, pumps, or valves.
- As liquid glycol ages, the cold plates of liquid cooling systems can corrode. As part of the vehicle’s maintenance, the cooling liquid must be replaced.
- In a battery, liquid travels through hundreds of small channels that are susceptible to clogging.
- The thermal challenges faced by batteries around the world vary based on the climate. For example, leaving the car in the sun for a long time, or living in an area where winter temperatures are extremely low. Temperature ranges must be tolerated by batteries at all times. It is essential that the battery cooling system is active even when the vehicle is not in use in order to achieve this.
- The effects of aging on thermal management must be taken into account. The amount of energy lost as heat increases as batteries age. Thermal management systems must be designed to handle these tougher conditions later in the battery’s life, not just during the first few years.
EV Battery Cooling and Tesla Steering Wheel Incident
EV Battery Cooling is a critical aspect of electric vehicle (EV) design, ensuring optimal performance and longevity of the battery pack. As EVs rely on lithium-ion batteries for power, maintaining an optimal temperature range is essential for efficiency and safety. Battery cooling systems, often utilizing liquid coolant or thermal management techniques, help regulate temperature during charging, discharging, and driving, preventing overheating and extending battery life. Effective cooling also enhances fast charging capabilities, reducing charging times and improving overall driving range.
On the other hand, incidents like the Tesla Steering Wheel Locked Up While Parked highlight potential challenges in automotive technology. Reports of steering wheel locking up while a Tesla vehicle is parked have raised concerns regarding vehicle safety and system malfunctions. Such incidents emphasize the importance of rigorous testing and continuous improvement in vehicle software and hardware to ensure safety and reliability.
Tesla and other automotive manufacturers must address such issues promptly through software updates and mechanical inspections to maintain consumer trust and confidence in electric vehicle technology.
Frequently Asked Questions
1. Do EV batteries need cooling?
Yes, electric vehicle (EV) batteries do require cooling to maintain optimal operating temperatures. Cooling helps prevent overheating, which can degrade battery performance and lifespan.
2. How do you cool down an EV battery?
EV batteries are typically cooled using various methods such as liquid cooling or air cooling. Liquid cooling involves circulating a coolant, usually a mixture of water and glycol, through channels or pipes within the battery pack to dissipate heat. Air cooling, on the other hand, uses fans or air vents to draw cool air over the battery cells to remove excess heat.
3. Do EV cars have cooling systems?
Yes, EV cars are equipped with cooling systems specifically designed to regulate the temperature of the battery pack. These cooling systems help maintain the battery within the optimal temperature range for efficient operation and longevity.
4. What is the cooling plate in an EV battery?
The cooling plate in an EV battery is a component designed to facilitate the heat dissipation process. It is typically made of a thermally conductive material, such as aluminum or copper, and is integrated into the battery pack to provide efficient cooling by transferring heat away from the battery cells to the cooling system, whether it’s liquid or air-cooled.
