How Electric Car Air Conditioning Works [Science Behind Electric Car Air Conditioning]

While the primary motive behind electric cars was to reduce our impact on global warming, there is no doubt that the same has also helped us save costs. Electrical cars are much more efficient, offering the same (if not better) results than a combustion engine. However, there is one very important concept that needs to be addressed, which is, How does an electric car’s air conditioning work?

Combustion engines have dedicated power sources for air conditioners, but electric car air conditioners need to tap into the battery for power. Doesn’t this impact the car’s performance as well? Does it reduce the car’s battery life? Are there any implications that you need to keep in mind?

How Electric Car Air Conditioning Works
How Electric Car Air Conditioning Works

In this article, we will take a closer look at the science behind electric car air conditioning, particularly the impact it has on your car’s range and how it works.

Does Using Air Conditioner On In An Electrical Car Impact Its Performance?

You may have noticed that turning on the air conditioner for your electrical car has a much more noticeable impact on electric cars compared to combustion engines.

Within the city, using your air conditioner can decrease your car’s range by 30%, while on highways and stretches, this impact gets reduced to 20%-25%. 

This reduction becomes even direr if the temperatures outside are extreme, i.e., over 95 degrees Fahrenheit.

Let’s take Tesla EVs, for instance. The AC compressor, in this case, is located at the car’s front, which allows the unit to draw power from the energy storage system (ESS).

For those of you who don’t know, the ESS is located in the back. The amount of energy lost when you are trying to heat your car in extreme cold or when trying to cool it up in extreme winters increases because of the distance it has to travel.

Electric vehicles draw 40 amps (depending on how much power you demand with your accelerator and the vehicle’s make) as per the National Electric Code (NEC). A car battery (depending on which one you choose) can offer anywhere between 50 amp hours to 500 amp-hours. A conditioning unit installed in most electrical vehicles usually uses about 32 amps when the temperature outside is moderate and about 36 amps when the temperature is extreme.

With a limited capacity battery, there is a very good chance that your air conditioner won’t be able to perform properly. Regardless of the batter installed, though, the math above shows that there is bound to be an impact on your electrical vehicle’s performance because of the air conditioner.

Before 2018, though, this impact was much more severe. This was when the concept of electric cars was being mulled over quite extensively.

Due to the issue of air conditioning, the European Union sanctioned a research team that was supposed to focus solely on creating a climate control system that would minimize the impact of the HVAC system(s) on a car’s range. The goal was to ‘extend the range of electric vehicles while enhancing passenger comfort.’

And so, the Horizon2020 XERIC (Innovative Climate-Control System to Extend Range of Electric Vehicles) was developed.

This was a hybrid system that would use a liquid desiccant cycle, a combination that would reduce the impact of humidity with the help of a vapor-compressive.

Read How To Fix A Stuck Electric Car Seat

How Electrical Car Air Conditioning Works

Here is how electric car air conditioning works
An electric car air conditioning system

Now that we know the impact of HVAC systems on your electrical vehicle’s performance let’s get down to the science behind the workings of electric car air conditioning.

When you turn on the air conditioner of your electrical vehicle, the electric current flowing towards the engine from the battery instantly gets split into two.

This is why you notice that your car may shudder a bit the moment you turn it on. If this was a combustion engine car, you would have heard the car’s RPM fluctuate a bit.

The electric current makes its way to the compressor and turns it on. When the compressor turns on, it pushes the refrigerant stored in the coils, increasing its pressure.

The compressed refrigerant immediately cools down the air being blown onto it by your car’s fan. The cool air is then pushed out the vent(s) into the car’s cabin.

Read Electric vs Hydrogen Cars

What Is a Compressor and How Does It Work?

An air conditioning system cannot work without a compressor, whether it is installed in a traditional vehicle, an electrical one, or in a building.

A compressor is central to the whole unit as it is responsible for circulating or pumping oil and refrigerant through the system. The compressor performs two major functions that are critical for cooling the air.

The first is raising the refrigerant’s pressure to make its temperature reach a point that it is higher than the temperature of the air present in the surrounding environment.

This is important as without that happening, there would not be a heat transfer taking place.

The second vital operation that the compressor carries out is that of creating an air pressure within the evaporator that is low. When a low-pressure condition prevails inside the evaporator, the refrigerant boils and vaporizes.

This makes huge quantities of energy produced from the heat in the cab of the vehicle get absorbed by the refrigerant.

Another crucial function that the compressor performs is to mix together the oil of the compressor and the refrigerant by circulating both of them simultaneously across the whole AC system.

If a compressor fails to properly carry out any of the two main functions it is responsible for; it would negatively impact the process of circulation of the refrigerant throughout the AC system.

In case of malfunctioning of either of the two functions, the refrigerant circulation may get reduced, or it may cease to take place completely. This consequently affects the cooling performance of the system.

All compressors are connected with two lines that are separately used for sucking in and discharging the refrigerant.

The inlet or suction line is responsible for sucking in gas from the evaporator that has low temperature along with low pressure. The discharge line, on the other hand, is responsible for facilitating the flow of the gas of the refrigerant that the compressor discharges and transmits towards the condenser.

The discharged gas has high temperature and high pressure. If you ever have to identify between the two lines, the one that is responsible for the suction of the refrigerant gas would always have a larger diameter than the one that aids its discharge.

Electric car air conditioning units have moderators in them, i.e., climate control sensors that tell the compressor to reduce its power consumption once the necessary or demanded temperature has been achieved. This is important to ensure that the compressor does not keep on consuming more energy.

Read How to Charge Your Electric Car On Road-Trip

How do Temperature Sensors Work?

The HVAC system in electric vehicles usually consists of a temperature sensor for the interior air and one for the air that is outside the vehicle.

They may use infrared rays to detect the heat of passengers or might use thermistors with two wires that sense the temperature and change resistance accordingly.

They are equipped with an aspirator tube that is used for pulling the air through the sensor with the help of a blower fan.

Here is an interesting point, maybe not for manufacturers who produce only electric vehicles but definitely for consumers.

The technology used for air-conditioners in electric vehicles was identified as being potentially compatible with not only EVs but traditional vehicles as well.

This means that it could diminish the environmental impacts of non-electric cars as well as improve the performance of their air-conditioners.

Furthermore, as the AC system of electric vehicles does not require the consumption of fuel, the car owners would save costs, and less air pollution would be produced.

Currently, none of the automobile companies has announced such an inclusion, but it is definitely a possibility, and we might witness it soon. 

Electric car’s air conditioning is fairly simple when it comes to cooling your car down. However, the ‘science’ (or the complexity) comes into play when you need to heat the cabin up. Just like in hotter temperatures, in extreme cold, your car’s efficiency will decrease.

Read Are Electric Car Charging Stations Free?

Electric Car’s Heating System

How electric car air conditioning works is a question all electric car owners should know the answer to
An air conditioning and heating unit of an electric car

In combustion engine cars, heating is fairly simple; the refrigerant starts drawing heat from the car’s engine (a process in which it ends up expanding instead of getting compressed).

The heated coolant then passes in front of the car’s blower, effectively heating the air up. A combustion engine’s efficiency doesn’t get impacted as much as an electric car’s when heating your car up.

Since electric cars don’t get nearly as hot (unless you are pushing the car to its limits), the car, again, needs to rely on battery power to heat your car up.

An electric car’s performance gets reduced by at least 17% when the heater is on in extreme temperatures.

Again, let’s take Tesla’s models into consideration. There is a dedicated electric heater in the car that heats your cabin up. To make sure that the heater does not use too much power, the ESS uses a positive temperature coefficient (instead of a negative one), where the electric current passes through a resistor.

We’ll explain what a resistor is in the next section.

As the current tries to flow through these resistors, it heats up, allowing the blower to pass the heat into the cabin. Here’s the rub, though.

As more and more electrical current passes through a resistor, it becomes ‘rigid’ in a sense. The hotter a resistor is, the more electricity it needs to get it hotter.

Think of your stove, for an instant. The hotter you want it, the more electricity it consumes. And the longer you keep it on, the higher your electricity bill is going to be.

This is precisely why the climate control sensors were integrated into the heating element as well.

Once the desired temperature is achieved, the car doesn’t keep on blowing heated air into the cabin. Instead, it shifts between hot and warm air to maintain the temperature.

Note: Combustion engine cars always blow hot air into the cabin unless you have a climate control option. That is why you may need to turn the heater down after a while. With Tesla cars, this is not an issue.

Read Are Electric Cars Reliable In Cold Weather?

What is a Resistor, and How Does it Work?

A resistor is an important component of the electric car air conditioning system
A resistor inside an air conditioning system

The main function of a resistor is to cease the flow of electrons within a circuit. They are passive in nature and only consume power. Resistors restrict the flow of current in any one of the following three ways:

  • They use a material that is less conducive to disallow the current from passing.
  • They thin the conductive material to diminish its ability to pass the flow of current.
  • They elongate the conductive material, so the resistor accumulates enough current to heat itself.

Some resistors have an insulating center with a wired wound around it which is conductive. Others use a carbon spiral instead of a physical wire.

However, the former is more stable and holds more precision than the latter. The thickness of the wire and the number of times it turns around the insulator determines the resistance it offers.

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The basic difference between the workings of the AC in a conventional car and an electric vehicle is that the former uses the engine to power it while the latter leverages electricity from the battery.

The rest of the functions of the AC systems in both kinds of vehicles are pretty much the same. The functionality of a heater is comparatively more complex than an electric car air conditioning system.