Do electric cars have heaters for winter?
Air conditioning in an EV – how does heating work in an electric car?
The engine in an electric car does not generate heat, so EVs must use specially designed heating and cooling systems. Maintaining the right temperature in the cabin in winter is not only a matter of driving comfort, but above all safety, since the windows must not be fogged up or frosted. You should know how an air conditioning system works in order to use it optimally.
The principle of air conditioning in the car
The air conditioning system works in conjunction with the car’s heating system and is responsible not only for cooling the interior in summer, but also for warm air in winter. The common element of both systems is the refrigerant, which, depending on the mode of operation, receives heat from the heater or is cooled in the radiator. Circulation of the refrigerant at as high pressure as 17 bar is forced by a compressor driven by a multi-ribbed belt, which in turn transmits the drive from a pulley on the engine’s crankshaft. In the cooling system, the refrigerant enters a condenser cooled by a momentum of air or a fan and changes from a gaseous to a liquid state. From there, the liquid is transported to a dehumidifier and then an expansion valve, where it transforms into a -4 °C gas. It then cools the evaporator, through which the air blown into the cabin flows. In a heating mode, on the other hand, the same refrigerant takes heat from the engine and transfers it to the heater, which heats the air flowing through it. An engine-driven fan is responsible for blowing cooled or heated air into the cabin. Knowing how air conditioning works in a combustion car, it is easier to understand the principle of this system in electric cars.
Air conditioning system in an electric car – what is the difference?
The electric motor does not emit heat, but this does not mean there is no heating in the car. The mechanism of operation of cooling and heating systems in electric cars is actually not very different from those found in combustion cars. The main difference is the power source of the compressor. It is not the crankshaft in this case, but the batteries for electric cars. Compressors in EVs have their own built-in electric motor, an inverter that converts direct current drawn from the battery into AC, and a separator that separates the compressor oil from the refrigerant. Among the advantages of the solution, where the compressor is powered directly from the battery, is the ability to run the air conditioner while parked, with the engine off. In new electric cars you can also find a heating system based on a heat pump, which somewhat resembles the split air conditioners used to heat buildings. The air-to-air heat pump can operate in both heating and cooling modes. In a heating mode, the warm air it produces is directly blown into the cabin, while in cooling mode it goes to a condenser, followed by a dehumidifier, expansion valve and evaporator. The heat pump is also powered by a lithium-ion battery using an inverter.
How to heat the interior of an electric car?
Turning on the car’s heating increases the energy demand for the compressor, which in the case of electric cars is associated with faster battery drainage. Given the small number of fast chargers and the extended battery charging time in cold weather, BEVs seem like a good option only for city trips, and that’s provided you have your own charging point at home. However, there are ways to reduce the electricity consumption of electric vehicles and hybrid cars in winter. First, preheat the car’s interior even before hitting the road. It’s best to plug it into a charger, or if that’s not possible, set it up in a sunny location. Secondly, while driving, it is a good idea to turn on the economy mode that reduces the energy consumption of individual systems to a minimum. If the car is equipped with heated seats and steering wheel, you can set the interior temperature to the lowest level or opt for no heating in the car. However, energy consumption for heating the interior depends not only on skillful energy management, driving speed and battery operating temperature, but also on the type of heating and proper insulation of the car’s interior.
The use of fan heaters
There are several different types of heating in electric cars, but the most common is an electric heater connected to a blower. Although the power of such heaters is mostly small, as low as 2 to 4 kW, in negative temperatures they greatly accelerate the process of battery drainage. It has even been tested in practice how long an electric car battery lasts in winter. Tests conducted by the American Automotive Association showed that in temperature conditions below -7°C, the average range of an electric car drops by up to half compared to optimal conditions of 24°C. This problem does not occur in warm climatic conditions, but in northern Europe or America, for example, where there are sometimes very harsh winters, the use of such heating in the car can make it impossible to travel long distances outside the city.
Advantages and disadvantages of a heat pump in the car
Heat pump is an increasingly common type of heating in electric cars. By properly compressing and expanding the heating medium, free heat energy drawn from outside can be used to heat the vehicle cabin. Tests in winter conditions have shown that this requires less energy than a traditional system with an electric heater, but only within a certain range of outdoor temperatures. At temperatures between 0 and 10°C, the heat pump is estimated to consume about 1 W of energy, so it saves 1-2 W for every hour of operation. At lower temperatures, the situation changes to the disadvantage of the heat pump. It is also often emphasized that the heat pump is a good solution only if the car is used for city driving and has a battery with a relatively small capacity. If the car is to cover longer distances, it is more profitable to invest in a model with a more capacious battery and a system based on a traditional resistance heater.
High Voltage Heater – what is it and how does it work?
The High Voltage Heater (HVH) is a device that is small in size and weighs just 2.7 kilograms, yet is very efficient. Unlike heat pumps, this technology is based on a water heating model instead of air heating. It can be used for both maintaining a comfortable temperature in the cabin and preheating or cooling the traction engine. The HVH heater is designed to operate over a wide range of supply voltages from 100 to 450 V, while its maximum heating power is as high as 7 kW. The high efficiency of this solution makes it applicable to large vehicles, such as trucks and buses. The most common application of this technology is electric parking heating of the driver’s cabin used in trucks, but it is also successfully used in passenger cars. Automobile design is increasingly combining all of these technologies in various combinations, or using the most comprehensive solutions possible to provide the greatest benefits.
Insulating materials and the range of an electric car
A very important aspect from the point of view of maintaining a comfortable temperature in the vehicle cabin is not only to produce heat or cold efficiently, but also to retain it where it is needed. In this regard, automotive components made of EPP foamed polypropylene, which features excellent thermal insulation, impact and deformation resistance, and minimal weight, are perfectly applicable. Even today, EPP has become a leading material that is widely used by car seat manufacturers. Among other things, it is used to manufacture seat fillings, headrests, armrests or car door panels, and even body components for passive safety. The excellent moldability and electrical properties of this material have also led to its use in the production of batteries for electric cars. Battery components molded from it protect sensitive cells from extreme temperatures, surges and mechanical damage. Thus, they make it possible to increase the range and safety of electric cars in many ways.
Do Electric Cars Work in Cold Weather? Get the Facts…
In short, yes. All cars (both gasoline and electric) have lower fuel efficiencies at colder temperatures, decreasing how far the vehicle can travel without refueling. However, because some electric vehicles (EVs) have a lower range than the typical gasoline car, these efficiency losses can be an important consideration when choosing an EV in places that have cold winters. Still, today’s EV’s work just fine in cold climates, and new models will be even better.
An EV on the slopes of Mt. Hood in Oregon. (Source Oregon Department of Transportation flickr/oregondot)
Gasoline vehicles and electric vehicles both lose in cold weather
In cold weather, all cars get less efficient. For gasoline-powered cars, factors like cold engine oil and increased idling can reduce fuel economy in freezing conditions by 20% or more. Overall, electric cars are more efficient than gasoline cars because an electric motor is much more efficient in turning stored electricity into motion than an internal combustion engine is in converting the chemical energy of gasoline to mechanical energy.
You can see (or feel) this inefficiency when considering the energy lost in the form of heat that leaves a gasoline car through the tailpipe and radiator. That heat is energy from the gasoline that is wasted. About 60% of the energy from gasoline is turned into heat, while only about 20% goes to drive the wheels. However, when temperatures dip, this “waste” heat is used to warm the cabin.
A battery electric car lacks a wasteful (but warm) engine, so an electric heating system (either a resistive heater or heat pump) is needed to keep the inside climate toasty on a chilly day. This electricity for heating will come from the same battery that’s used to power the electric drivetrain, so the effective range will drop in cold weather (assuming the driver chooses to use the heater).
Not all of the loss in range is due to the climate control system. Batteries also have lower performance as the temperature dips due to the impact of the temperature on mobility of electrons through the battery. To keep performance and reduce accelerated aging of the batteries, many EVs have a thermal management system that keeps the battery warmed (or cooled in hot temps) to an optimum temperature range. Warming the battery pack takes power that reduces range. Heating the cabin and battery combined can increase the auxiliary power load on an EV like the Nissan LEAF from below 1 kW to almost 3kW as the temp goes from 68 ºF to 10 ºF.
There are ways to reduce the impact of cold temperatures on the performance and range of EVs. One is to heat the cabin and/or battery before unplugging the car. This “preconditioning” of the EV can even be done by a smartphone or watch app on some cars. It’s similar to the use of engine block heaters and remote start systems used on gasoline cars (though without the exhaust of an idling engine). Grid electricity is used by the EV to warm the battery and interior, so that more of the car’s stored electricity can go to driving the wheels.
Electric vehicles are also getting better at cold temperature performance. For example, using high efficiency heat pumps can provide cabin heating with much less drain on the battery than a resistive heater. Other design improvements can help such as using heat from the electric motor and power control electronics to heat the battery and/or the vehicle cabin. These types of improvements have typically been found in EVs that were designed from the start to use an electric drivetrain, so we should see these more efficient features become more common as more manufacturers build “EV-only” models like the Chevy Bolt and BMW i3.
People are buying, and loving, EVs in cold places
So how do EVs work in the real world for people in cold climes? The EV fleet management company Fleet Carma has tracked trips in the Nissan LEAF in Canada and the U.S. and found that overall range drops from close to 80 miles in shirtsleeve weather to 50-60 miles when driven in below freezing conditions.
This is a noticeable drop, but still leaves enough range for many drivers. For example, our survey of U.S. drivers found that 54% reported daily driving of less than 40 miles and 69% drive less than 60 miles on the average day. For a longer range EV, like the Tesla Model S or the upcoming Chevy Bolt, the impact of cold weather is likely to be less of an issue. These cars have more total range available, so any loss of range will impact driving utility less and offer drivers ample battery capacity to run both the motor and heaters for extended drives. For example, Telsa reports that their Model S 70D model loses about 19% range when driving in 0 degree Fahrenheit weather with the heater on, reducing the range to 195 miles.
Nissan LEAF average range as a function temperature. Data from Fleet Carma via “Effects of Regional Temperature on Electric Vehicle Efficiency, Range, and Emissions in the United States”
Tesla Model S 70D highway (65mph) range as a function temperature. Because of its larger battery pack and more efficient thermal management system, the Tesla retains nearly 200 miles of range at 0 degrees Fahrenheit. Data as reported on Tesla Motors website.
If they work in Norway, EVs can handle our winters
To see if EVs work in cold weather, one can look at the example of Norway. Norway’s generous incentives for EVs has made electric vehicles popular in this Nordic country. Over 70,000 EVs have been sold in Norway, and EVs made up over 20% of all new cars sold in the first 9 months of 2015. Subsidies are a major reason for these high EV sales rates, but drivers wouldn’t be picking these cars if they didn’t work for their driving needs. Not only are Norwegians picking EVs, but also many of them are choosing shorter range EVs from Nissan and Volkswagen, despite the sub-freezing average winter temperatures. EVs are also working closer to home in colder climates like Canada and Vermont.
One Chevy dealer in Quebec has even moved his dealership to selling mostly Chevy Volt plug-in hybrids.
EV performance is impacted by cold weather, but an electric vehicle can be a good choice for many Americans, even those in the northern reaches of the country. And in the Northwest and Northeast states EV drivers can access some of the cleanest electricity in the country, greatly reducing emissions from driving (use our EV tool to calculate emissions in your local area). Affordable longer range EVs will make cold weather even less of an issue—but even today’s EVs are working all-year round in every state in the nation.
About the author
David Reichmuth’s work focuses on analyzing new vehicle technologies and advocating for policies that support the increased electrification of transportation. Dr. Reichmuth has testified at hearings before the US House of Representatives, the California State Legislature, and the California Air Resources Board, and he is an expert on California’s Zero Emission Vehicles regulation.
Heating & Cooling Are A Challenge For Electric Vehicles
Heating and cooling the cabin of electric vehicles needs to be more efficient to avoid loss of range.
November 22, 2021
If you are reading CleanTechnica, chances are you are a strong supporter of electric vehicles and would like to see more of them on road. Cars powered by gasoline and diesel engines are hugely inefficient. According to AAA, only about a third of the energy contained in a gallon of gasoline ever gets used to push a vehicle forward. Nearly two-thirds of that energy is turned into heat, some of which is absorbed by the coolant with the rest going out the exhaust pipe.
It’s hard to believe such a wasteful process has become the standard means of powering the world’s transportation sector, but there is good news. Some of that waste heat can be recaptured from the coolant to heat the interior of our vehicles. As wonderful as electric vehicles are, they have no stream of waste heat that can be tapped for the same purpose, which poses a challenge — how to keep EV drivers and passengers comfortable when it’s cold outside? The corollary to that is how to keep them cool when it’s hot outside?
An Electric School Bus In Alaska
According to Alaska Public Media, there is exactly one battery-electric school bus in the entire state. It transports school children in the Alaska Gateway School District, which includes the town of Tok near the Canadian border. Temperatures in the area can dip as low as -40 degrees F.
You might wonder how well the batteries in the bus function in such bitter cold conditions. Gerald Blackard, co-owner of Tok Transportation, says the bus has performed flawlessly for the past year, even in the most bitter cold weather. The one issue is keeping the interior heated. [Note: In Alaska, buses must be kept at 45° F or more. School children are required to wear warm clothing while riding back and forth to school.]
What Blackard has learned is that it takes more battery power to heat the bus than it does to drive the 30 miles a day needed to complete its route. “On January 27th, we had 38 below,” he says. “The bus’s efficiency that day was 3.46 kilowatts per mile. So this fall, in August-September, we were running between 1.4 and 1.7 kilowatts per mile. Even with a little bit of insulation on the batteries and kind of covering up the engine compartment to try to hold in as much heat as we could, we were still using more energy to heat the bus than we were to drive the bus.”
Blackard says he has been sharing the data he collects about how the bus operates with the local utility company, the University of Alaska Fairbanks Alaska Center for Energy and Power, battery manufacturer Proterra, and Thomas, the North Carolina based manufacturer of the bus. “I’m in contact with [Thomas] often,” he says, “and they’re always curious to see how things are going and making sure that it’s working properly.”
Tok Transportation uses a 10.8-kilowatt solar installation to recharge the bus, but since it uses 22 kilowatts of power while recharging, it needs to supplement the electricity from the solar panels with electricity from the local grid. A battery storage component is planned for the future when funds become available. Most of the $400,000 cost of the bus and the solar system was paid for by the Alaska Energy Authority.
About Those Rivian Delivery Vans For Amazon
This week, a loose-lipped test driver let it slip that the pre-production Rivian delivery vans being built for Amazon use up to 40% more battery power if the heating or cooling systems are turned on. Those vans are supposed to have a range of 125 to 150 miles. Subtracting 40% leaves them with only 75 to 90 miles of range.
The company acknowledged to Reuters that the testing was taking place, but cautioned that these pre-production models do not have the insulation that will be included in production vehicles. That may be true, but is seems unlikely Rivian is going to add enough insulation to the vans coming off the assembly line to make a significant difference.
Rivian is finding out what drivers of EVs already know. Activating the climate controls in an electric car means less energy will be available for moving it down the road. There’s a reason why in winter, Nissan LEAF drivers like myself use the heated steering wheel and seat warmers instead of the heater whenever possible. [The good news is, when you turn on the heat in an EV, it comes on instantly, unlike a conventional car that may need several miles of driving to warm up.]
For over a century, drivers have been taking advantage of the waste heat their cars create to stay warm in winter. We never stopped to ask if such wastefulness was good for the environment. Of course it isn’t. The new age of electric vehicles is upon us and we no longer have a source of waste heat at out fingertips.
When air conditioning first became a thing for automobiles, the compressors were so inefficient they could reduce gas mileage by as much as 20%. But as gas prices went up, A/C systems became more efficient. The same thing will happen with cabin heating for electric vehicles. As usual, Tesla has been at the forefront of innovation with its Octovalve, which alone enabled a 10% increase in range for the Model Y.
Early EVs used resistance heating to warm the interior — the same 1960s technology used by electric space heaters. Electricity is passed through a coil of wire, which heats up and warms the air around it. It works, but it uses a huge amount of electricity for the heat created. In other words, it’s inefficient, just like the internal combustion engine EVs are supposed to replace.
Tesla has been a leader in improving heat pump technology for its vehicles — so much so that is may get into the business of making heat pumps for residences and commercial buildings. According to Kyle Field, Tesla redesigned the heating and cooling systems for the Model Y to reduce the inefficiencies of heating and cooling with electricity and maximize the efficiency of the vehicle’s thermal systems.
The cooling circuit was integrated into a single heating and cooling management system for the vehicle that optimizes the thermal energy flowing throughout the vehicle and integrates the Octovalve with a completely redesigned heat pump.
In the final analysis, the transportation sector will need to find new ways to control the cabin temperature of vehicles, now that it doesn’t have a ready supply of surplus heat to work with. Fortunately, Tesla is blazing a trail for the others to follow.
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