Replacing the internal combustion engine with an electric motor and a battery solved many problems. However, it required Tesla to reengineer climate control. Simply put, Tesla takes a different approach to air conditioning than conventional cars.
In a traditional car, cabin heating and cooling are provided by the engine coolant. However, a Tesla does things very differently because there is no engine. This article takes a look at how Tesla solves the problem of climate control.
So How Does the Air Conditioner Work in a Tesla?
Tesla engineers place the AC compressor at the front of the car. This allows the AC to draw power from the Energy Storage System (or the ESS). The ESS is located in the back.
The compressor uses 400 volts and routes refrigerant to a chilling unit. It then provides cool air through vents and into the car.
This process is very similar to an internal combustion engine-powered car. The heating system is a bit more complex. Cars with an IC engine draw heat from the engine’s coolant. Nearly 30% of the heat due to combustion is transferred to the coolant.
This provides a great source of heat. The incoming air is passed through a radiator which contains the hold engine coolant.
This system does not exist in an electric car.
Instead, Tesla has replaced the heater solution with an independent electric heater. The only problem is that electric heaters draw too much power. Tesla had to make sure that the heater doesn’t drain excessive energy from the battery.
However, just as conventional cars are affected by ACs, Teslas also experience a performance impact. This problem of performance is an important issue for manufacturers of electric vehicles.
It goes without saying that running the AC will lower the range of your Tesla.
What Happens When You Turn the HVAC On in a Tesla?
When you turn the air conditioner in a Tesla, a few things will happen. The electric current floating toward the engine from the battery is split into two.
This is why you will notice that your car struggles when you turn it on. In the case of an internal combustion car, you would’ve heard the RPM roar a bit.
The electric current will activate the compressor. After you turn the compressor on, it passes the refrigerant stored in the coils. This will increase the overall pressure of the refrigerant. The compressed refrigerant cools the air blown onto it by the Tesla’s fan.
The cool air is then released into the car’s cabin through the vents.
The air conditioner in a Tesla cannot work without a compressor. This is true whether the car is powered by a battery or an IC engine.
A compressor plays a central role in climate control and HVAC. It performs two major tasks that are critical for regulating air temperature.
The first is to increase the pressure of the refrigerant. The refrigerant’s temperature will get higher than the ambient air. Without this happening, heat transfer would not take place.
Secondly, the compressor creates low air pressure within the evaporator. This low pressure allows the refrigerant to boil and vaporize.
This allows huge amounts of heat in the cabin to be absorbed by the refrigerant. The compressor mixes the compressor’s oil and refrigerant by circulating them through the AC.
If the compressor fails to carry out these objectives, it would not cool Tesla. This will obviously affect climate control and the cooling performance of the EV.
Compressors are connected by two lines that are used to circulate the refrigerant. The inlet line is responsible for taking in gas from the evaporator. This gas has a low temperature and low pressure. The outlet line flows the refrigerant to the condenser. The refrigerant has high pressure and temperature.
Pro tip: The inlet will always have a larger diameter than the outlet.
Tesla air conditioners have climate control sensors in them. These sensors tell the compressor to reduce its power when the necessary temperature is achieved. This will prevent the compressor from consuming more energy than is necessary.
The air conditioner in Teslas uses two temperature sensors. One for the interior air, and one for the outside air.
It may also use infrared rays to detect the heat of passengers. Some systems use thermistors with two wires to sense the temperature and make appropriate adjustments.
They are equipped with an aspirator tube to pull air through sensors using a blower.
Interestingly enough, the technology for ACs in Teslas is compatible with traditional vehicles as well. This means that using this technology can reduce the environmental impact of traditional cars. It can also improve the performance of their HVAC units.
Furthermore, the AC unit of Teslas in Michigan does not require fuel. This would save car owners money in the long run and prevent air pollution.
Although Tesla aims to alleviate the environmental impact of traditional cars, there is a problem. Some Tesla models use a GHG compound called HFC 134a for their AC units. This refrigerant is bad for the environment, according to activists. This is because it traps 1400 times more heat than CO2 over 100 years.
This is a bitter pill to swallow for advocates of electric vehicles. Teslas that are propped up as solutions to climate change are carrying a potent refrigerant.
It makes sense for Tesla cars to use alternatives to reduce the global warming impact. However, very few electric cars use climate-safe alternatives.
Tesla is reluctant to use the alternative because of cost and supply chain problems.
Activists are concerned because the refrigerants slowly leak into the air over years. This is often a problem with cars that are discarded in junkyards.
A climate-safe option to HFC 134a is HFO 1234yf (short form YF). This hydrofluoroolefin has 0.3% percent of the climate impact of HFC 134a. A serious problem with the refrigerant is that it needs more energy. Experts believe that it requires 10% more energy.
This is a problem with Teslas where air conditioners take too much power as is. The final nail in the coffin for YF is that it is not accessible. Not all auto shops will carry YF to service electric vehicles.
Until very recently, HFC 134a was the best climate-safe alternative. But it’s still far from an ideal solution.
A Tesla electric car AC uses 1 to 2kW of power. The AC becomes more energy-efficient if the difference between the ambient air and the cabin decreases. Tesla would use 2 kW to cool the cabin at 70°F. This is only true if the ambient temperature is at 110°F.
But what happens if you want the cabin temperature to be 85°F? At the same ambient temperature, you would consume only 0.2kW of power.
Let’s take a look at this relationship with the table below.
|Ambient Temp (°F)||Target Internal Temperature (°F)||Difference in Temperature (°F)||Power Usage|
The energy usage reduces if the target temperature is closer to the ambient temperature.
In general, Tesla electric cars do well against other cars on the road. This is because the system uses positive temperature coefficient (PTC) heaters. They meet the gold standard in energy efficiency.
For obvious reasons, using the AC will reduce the range. The effect is more dramatic in extreme heat and cold. For example, extreme heat can reduce the range by up to 41%.
This is because the air conditioner needs to work harder to cool the cabin. Here are a few things you can do to increase the Tesla’s driving range:
- Turn the AC off: This will boost your range dramatically. It makes more sense to turn the AC off if you’re making a short trip.
- Reduce speed: Recycling the speed will conserve power to give you more miles.
- Drive with a Full Battery Pack: Use every opportunity to charge your Tesla’s battery pack.
A major drawback that Tesla cars face is the stress on the battery pack. As the usage of the AC increases, so too does the strain on the battery. It gets harder to keep the battery at an optimum temperature.
For optimal temperature and performance, Tesla has provided ESS with its own cooling system. This distributes heat more uniformly within the battery pack. It also ensures that temperature variations between the cells are minimal.
It is important to keep the battery pack running at an optimum temperature. Otherwise, this would affect the performance of the Tesla electric car. This is why Tesla uses an ingenious heat pump.
The heat pump works by passing an antifreeze mix around the EES. This provides the EES with its own cooling system.
There are two major advantages of using heat pumps:
i) They can be operated in both directions
ii) They can transport more heat than the energy needed to power them
The ratio of heat delivered compared to the input power is known as the COP. The COP or Coefficient of Performance of 1 can’t deliver more heat than the energy supplied to it.
Most heat pumps can work across a limited temperature range. This is a problem because it will stop providing heat in extreme cold. Also, the COP decreases when the difference between hot and cold temperatures increases.
Whether you want to cool or heat the cabin, the heat pump will require energy. The required energy is proportional to the volume of air and temperature difference. Most Teslas have small volumes compared to houses, and wouldn’t require much cooling/heating capacity.
The only problem is that most cars have poor insulation to prevent heat exchange. To make things worse, the glass and metal on Teslas make things difficult for HVAC.
A heat pump that draws 1kW will generate heat equivalent to between 2-3kW.
Heat pumps are useful because they reduce the use of the battery to power the HVAC. The energy that is saved is used to power the car for extra miles.
Range becomes a major problem in extreme climates. For starters, driving through cold air outside results in more drag. Then energy is lost from heating the battery. Also, energy is used to provide heat to the cabin.
This is where heat pumps come in.
Heat pumps can generate 3 times the thermal energy from electricity. This is an efficiency of 300%. Moreover, the heat pump uses less energy to heat the cabin. This translates into a higher overall range.
The Model Y was the first Tesla to use heat pumps. All prior models used a conventional electric resistance heating system. Tesla has started to equip all their newer cars with heat pumps.
Elon went so far as to praise the technology on Twitter.
A New Invention? Tesla’s Refrigerant-Based Seats
Tesla filed a patent in 2019 for refrigerant-based seats. The company has plans to roll out seats that use coolants to increase passenger comfort. This system is proposed to be more efficient compared to the current cooling technology.
The new seats would be more efficient than electric seat heaters. They would also provide better cooling than simply running chilled air through vented seats.
In the case of electric vehicles, traditional seat heating systems take up too much space. Moreover, they require heat to travel through multiple layers of fabric and material.
However, the new fluid will efficiently transfer heat with the circulation of fluid. The patent includes multiple layers inside the seat. A layer of heating/cooling fluid will occupy the outermost layer of the seat. This fluid will circulate under the layer to ensure that all parts are heated/cooled.
So there you have it, a detailed breakdown of air conditioners in Teslas in Michigan. The automaker is always one step ahead of the curve with ingenious inventions. Was this article on “how does the air conditioner work in a Tesla” informative? Let us know in the comments section!
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