Do Electric Cars Need Radiators?
Electric cars are different from regular fuel-powered cars in many ways. They have huge battery packs but fewer moving parts in their motors, requiring different maintenance routines. You may wonder if electric cars have radiators, too.
Electric cars can have radiators because they need to cool down their batteries and other components like the motor and converters. However, they may use different ways to cool down the battery pack, such as water pumps that run around the battery pack and circulate the coolant liquid to absorb heat.
This article elaborates on how radiators work, why EVs need cooling systems, and what cooling systems are used in electric vehicles.
Table of Contents
- What Does a Radiator Do?
- Air-cooled Engines
- Radiators in Electric Cars
- Different Cooling Options in EVs
- Final Thoughts
What Does a Radiator Do?
Radiators are critical components of all ICE cars because of how their engines work. They burn fuel to power the car and create energy through their moving parts. These processes can generate considerable amounts of heat, which can be dangerous for the car, especially in hot seasons.
A radiator is part of the vehicle’s cooling system, which helps cool down the engine through a simple design. It consists of a large metal box with rows of thin blades.
It has a thermostat to monitor the temperature, a liquid coolant that circulates through the radiator and the engine via hoses, and a fan to cool down the hot coolant.
The coolant liquid goes from the radiator to the engine, absorbs the heat, and returns to the radiator. The radiator has thin metal fins that send the heat to the air and cool outside air from entering the radiator through the car’s grille. Then, it goes into the engine again and repeats the whole process.
This process goes on as long as the car engine is working, even when it’s idling in traffic. The thermoset, placed between the radiator and the engine, checks the temperature and ensures the coolant flows properly.
Another essential component of a radiator is the pressure cap that seals the whole system and maintains proper pressure. The radiator doesn’t work properly without this pressure, causing the coolant to boil and overflow.
In addition to cooling down the engine, a radiator helps warm up the engine, too. When the temperatures are low, the radiator closes the thermostat and doesn’t allow the coolant to circulate around the engine. This way, the engine burns fuel and generates heat with its moving parts.
The process of cooling a car engine described above mainly applies to liquid-cooled engines. While most modern cars are liquid-cooled, some older vehicles are air-cooled. Some examples include the 1964 Porsche 911 and the Volkswagen Beetle. However, these days it’s hard to find cars with air-cooled engines while some all-terrain vehicles, motorcycles, and even aircrafts effectively use these engines.
As the name suggests, the engine relies on airflow to cool down. There are some fins on these engines that pull the generated heat away and attract cool air from outside. They may also feature ducts installed around the engine that make sure the hottest areas of the engine get enough airflow.
This design means an air-cooled engine doesn’t need a radiator. Nor does it need a coolant or water pump or hoses to circulate around the engine.
Radiators in Electric Cars
Electric cars don’t have engines like internal combustion engine vehicles do. They have electric motors that work with the power generated by the batteries and propel the car. EVs have more than 90% efficiency, which means they turn 90% of the battery power into energy, producing much lower waste in the form of heat. Plus, they have much fewer moving parts than ICE cars, which means almost zero heat is generated in the engine.
However, the heat is generated somewhere else: the batteries. Most electric vehicles need a sort of cooling system – called heat exchangers on Tesla cars, for example – around their batteries.
That’s because, during charge and discharge cycles, batteries can heat up, and the faster the battery discharges, the more heat it generates. Although they don’t heat up like ICE cars to be dangerous, they can cause different problems.
The main problem has to do with the way batteries work: they rely on the difference in potentials between the positive and negative ends of the battery. This difference forms the battery’s voltage, which is very high in EVs.
When a battery heats up, the electrons are excited and move inside, decreasing the voltage difference. As a result, the batteries won’t work properly.
Battery temperatures should remain between 20 and 40˚C (68 to 104˚F). In addition, the temperature of all battery cells should always be the same. Otherwise, they’ll charge and discharge at different speeds, lowering the efficiency of the battery pack. There’s even the risk of fire in extreme cases due to overheating.
Another problem caused by excessive heat is reduced range. Batteries are at their best when they’re at 70˚F. That’s why manufacturers always recommend parking your EV in the shade to extend the battery’s lifespan and range.
That’s why electric cars need cooling mechanisms to keep battery temperature within a certain range. However, different EVs use different mechanisms. For example, the Nissan Leaf uses fans for air-cooling, which isn’t very efficient and has made Nissan Leaf notorious for overheating.
That said, batteries aren’t the only EV components that require cooling. Different manufacturers may decide to install cooling mechanisms on different components. For example, Tesla uses these systems for ACs and batteries. Here are some other parts:
- AC/DC converter
- Controlling electronics
Different Cooling Options in EVs
Manufacturers may decide to cool down different components and use various ways to do so. Here are the most common ones:
Cooling electric car internals using airflow follows the same principles as those mentioned for regular cars. It’s the same way a fan cools a room, which you can guess isn’t that efficient. Like ICE cars, older models of EVs use this cooling method, and some of them, like Nissan Leaf, have overheating problems due to this cooling method.
A significant restriction of air-cooled systems is that they rely on strong wind flows to cool the battery or motor. So, if it’s a hot day or you’re driving at a low speed, the car will heat up more quickly.
This method is highly popular among EV manufacturers because it’s more efficient due to higher heat conductivity. Tesla, BMW, and Jaguar are among the biggest names that use this cooling method. They may use radiators or other structures to run these coolants around the batteries.
Most manufacturers use glycol as a coolant and transfer it through a series of pipes that run around the components that need cooling.
However, they aren’t without issues as they may leak or require maintenance. For example, some cars like the Chevy Bolt require coolant replacement after 150,000 miles, while Tesla guarantees they’ll work for the car’s entire life.
Like regular cars, EVs use water pumps to circulate the coolant around the battery or motor. However, EVs have a smarter way of using the pumps; the ECU activates the coolant when needed. Since these water pumps are electrically powered, this smart activation only uses batteries when needed, increasing battery efficiency.
These water pumps are used in the same design as regular cars’ radiators but are much smaller because there’s less heat.
In addition, they’re installed in front of the car next to the car grilles. This way, yhey can release the air inside the radiator’s fins outside through the grilles. However, in some cars like Tesla, the grilles have a cover that opens and closes from inside whenever the ECU decides it’s necessary.
Both air-cooled and liquid-cooled systems can use fins to transfer heat outside the motor or battery, depending on the model and make of the EV.
Check out this interesting YouTube video outlining the cooling system and water pumps inside Tesla Model 3:
Refrigerants are another cooling agent mostly used in AC systems. It runs through the chilling unit and cools down the air pumped out of the AC vents. However, some manufacturers also use refrigerants to cool down their battery packs. The BMW i3 is one of these models. But there are environmental concerns about these refrigereants because they’re green-house gases and if they leak, they can damage the environment.
Many EV manufacturers, including Tesla, have recently turned to heat pumps, although it’s not a new technology. They can be more efficient than other methods, so they may become more prevalent in the future.
Heat pumps work the same way as house heat pumps: they take heat from where it’s not needed to a place where it is. During winter, the heat pump transfers the heat generated by batteries into the cabin to warm it up.
There’s a catch, though: they don’t work under 25-30˚F, which can be a big disadvantage for car owners in cold areas. However, manufacturers are working on the technology to work at very low temperatures.
There are other cooling methods like fins and phase change materials, but they’re not that efficient, and manufacturers have stopped using them.
Electric car motors don’t generate heat as much as regular ICE cars because they’re highly efficient and don’t burn fuel. However, they produce lots of heat in their batteries, requiring them to cool down to avoid damages. That’s particularly important because batteries should have a fixed temperature.
The most efficient cooling method uses a coolant liquid, mainly glycol, that runs through pipes around the battery pack, absorbs heat from different components, and sends it out.
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