How Does AC or Heat Work in an EV?
Air conditioning in an electric car works similarly to a traditional car with an internal combustion engine; the difference is how the system is powered.
Typically, the gas engine has a series of belts and pulleys that turn engine accessories. Those belt-driven accessories include the main radiator fan, the alternator, and, in older cars, the power steering pump. This is also how the air conditioning is powered — but in EVs, it's powered by an electric motor.
A sweltering summer day will test any AC system, and you can expect to lose as much as 20 percent of your typical range in an EV. That's similar to what you might expect from a similar gas-powered vehicle.
How AC Can Affect EV Range
Maintenance and Troubleshooting Tips for AC in an EV
Future Innovations in EV Air Conditioning
How AC Systems Work
How AC Can Affect EV Range:
Anytime power is being used for anything other than making the car move, it will negatively affect EV range. Yes, even charging your phone will reduce your range (by a very small amount), but not nearly as much as the air conditioning. The effect AC has on range is influenced by many things, including the temperature outside and how efficient the AC system is.
Other influences include the color of your vehicle and how much light is let in. Some EVs, such as the Tesla Model X, have windshields that stretch well past and over the driver's head, which can slow-roast them on a hot day, forcing you to run the AC for longer and at a higher speed.
For the most part, there isn't an air conditioning system that has a clear advantage over others. That holds true whether we're talking about EVs or gas cars. There is a difference in the effects on longevity, though.
As we mentioned, running your car’s air conditioning will increase its energy consumption and reduce your range. When you reduce range, it means you need to recharge the vehicle more often throughout its lifespan, and more charging means reduced battery longevity. In a gas car, the immediate drawback is a reduction in fuel economy. The long-term effects of the added stress on an engine are negligible in most cases.
Maintenance and Troubleshooting Tips for AC in an EV
Modern air conditioning systems don't need a lot of maintenance, and the issues that arise are common between EVs and gas cars.
The refrigerant is locked in a closed-loop system, so you'll rarely, if ever, have to top it off. If it leaks, you'll definitely know it because the customarily cold air from your vents will blow hot and humid.
You won't have to worry about screeching or broken belts in an EV like you might in a gas car, but the electric motor that turns the compressor is a potential liability. None of the main AC components are serviceable by the average consumer, so if you notice a dip in cooling performance, your nearby service center should be your first stop.
Pro tip: Replacing old air filters can reduce the amount of air resistance in the system, reduce the amount of power drawn, and, in turn, increase the EV range. Over time, this adds up to help extend your car’s battery life.
There are also other steps you can take to improve efficiency:
- Park in a shaded spot will ensure you won't have to run the AC on maximum when you get back in
- Pre-condition the climate while the car is charging will also reduce the initial power draw from the battery
Future Innovations in EV Air Conditioning
We've come a long way from the adoption of vehicle air conditioning way back in the 1950s. Not so long ago, it was good advice to check your air conditioning before a summer road trip. Today's systems are far more reliable, and advances in chemistry have greatly reduced the harmful effects of stray refrigerant on the environment.
In addition to pre-conditioning your vehicle, there are a handful of other improvements that can make climate control more efficient. Reflective coatings on the windows can reduce the amount of heat transmitted into the cabin, as can sunshades that are built into many vehicles.
Seat fabric can also reduce the perceived interior temperature, with new materials and foam padding that transfer heat more readily, almost like a memory foam mattress.
In the same manner, ventilated seats have been proven to be more efficient at cooling passengers than AC systems. A U.S. Department of Energy study found that if all vehicles had ventilated seats, it would cut AC-related fuel use by 7.5%.
On the other side of climate control, EVs have seen more innovation. Heating a car on a cold winter day can draw a lot of power. In cars with a gas engine, the heat of the engine would warm up the air temperature.
In many EVs, however, a conventional resistance electric heater (think of those glowing orange coils in old space heaters) draws an alarming amount of power from the battery pack.
That's where heat pumps come in. They essentially reverse the cooling process, using the electric compressor and resulting heat instead of the cooled evaporator, which is much more efficient.
Heat pumps can be found in new Teslas and EVs from BMW, Nissan, Toyota, Ford, Hyundai, and Kia, to name a few. In cold weather regions, these heating systems should be in higher demand by shoppers in order to reduce the likelihood of being stranded by the reduced range or freezing in said stranded vehicle.
As common and similar as air conditioning is between EVs and gas cars, automakers are always looking for new efficiencies and technologies. While it may be a while before we see major breakthroughs, small improvements will continue to keep us cool and comfy, no matter the weather.
How AC Systems Work
To get a clearer understanding of how AC can affect an EV or gas-powered car, let's look into the basics of how air conditioning works.
Whether it's in your vehicle or in your home, an air conditioning system has a hot side and a cold side. A liquid refrigerant flows through tubes to move heat from one side to the other.
On the cold side, the refrigerant passes through an evaporator coil that transforms the liquid into a gas and, in the process, cools the tube and refrigerant significantly. A fan blows air across these tubes and pushes that air into the vehicle cabin.
That refrigerant then travels out of the passenger compartment and into the air conditioning compressor, where the gas transforms back into a liquid and heats the refrigerant.
That heat is dissipated through its own radiator and then recirculated back into the evaporator coil, beginning the process all over again. The main power draws are the AC compressor and the fans that blow the cooled air into the cabin.