Heat pump in an electric car: how it works and why it is needed

In the world of electric mobility, innovative solutions constantly emerge to improve efficiency and comfort of electric transport. One of the most important technologies that significantly impacts range and energy efficiency, especially in cold weather, is the heat pump. This technology has become a breakthrough for electric vehicles, substantially reducing energy consumption for cabin heating and significantly increasing driving distance on a single charge during cold seasons.

What is a Heat Pump in an Electric Vehicle

A heat pump in an electric vehicle is a system that functions on a principle opposite to that of a refrigerator. While a refrigerator removes heat from the interior space and releases it outside, a heat pump does the opposite – it captures heat from the surrounding environment and transfers it inside the vehicle to heat the cabin or the battery pack.

Unlike traditional resistive heaters (heating elements), which convert electrical energy directly into heat, a heat pump uses energy much more efficiently. It can "pump" heat from a colder environment to a warmer one, consuming significantly less electricity than would be required for direct heating.

As industry experts note: "Any electric vehicle without a heat pump is already a dinosaur." This statement has a solid foundation, as climate control systems (heating and air conditioning; HVAC) are the largest energy consumers in an electric vehicle after the drive itself.

How a Heat Pump Works in Electric Vehicles

The operation of a heat pump can be divided into four sequential stages that form a closed cycle:

• Evaporation: Naturally heated antifreeze or ambient air is directed to the heat pump's evaporator. Here, heat is transferred to the refrigerant (a special fluid with a low boiling point), which converts from liquid to gas state. This process allows heat absorption from the surrounding environment.
• Compression: The gaseous refrigerant is drawn into a compressor, where its pressure increases. During compression, the gas temperature can rise to 80°C, significantly higher than the air temperature in the cabin.
• Condensation: The compressed hot gas moves to the condenser, where it transfers its heat to the cabin heating system or the battery. During this process, the gas cools down and converts back to liquid.
• Expansion: The liquid refrigerant passes through an expansion valve, where its pressure decreases, causing a sharp temperature drop. The cooled liquid then returns to the evaporator, and the cycle repeats.

n some modern electric vehicle models, heat pumps can operate in reverse mode, allowing not only heating but also cooling of the cabin and battery. This makes the technology versatile and suitable for use throughout the year.

Why a Heat Pump is Needed in an Electric Vehicle

The main reason for implementing heat pumps in electric vehicles is the significant reduction in energy consumption to maintain a comfortable temperature inside the vehicle. Studies show that when using conventional heating systems (resistive heaters), an electric vehicle can lose up to 45% of its normal range in cold temperatures.

Traditional vehicles with internal combustion engines (ICE) have a significant advantage in cold weather: they use waste heat from the engine to warm the cabin. This "free" heat doesn't affect the vehicle's range. Electric vehicles, however, have highly efficient electric motors that produce little heat, so energy from the battery must be used for heating, which directly impacts driving range.

This is where the advantages of a heat pump come into play: it can provide efficient cabin and battery heating while reducing energy consumption and increasing range in cold weather.

Advantages of an Electric Vehicle Heat Pump

The implementation of heat pumps in electric vehicles provides users with a range of benefits that significantly improve the electric transport experience, especially in cold climates.

Energy Efficiency Compared to Heating Elements

The main advantage of a heat pump is its energy efficiency compared to traditional electric heaters (heating elements). To evaluate this advantage, the Coefficient of Performance (COP) is used — the ratio of heat produced and transferred to the cabin to the energy required to create and move this heat.

A resistive heater (heating element) has a COP equal to 1, meaning it converts 100% of the consumed energy into heat. In contrast, a heat pump has a COP of 3 to 4, which means: for each unit of consumed electricity, it can transfer 3-4 units of heat. Thus, a heat pump is 3-4 times more efficient than a resistive heater.

Studies show that electric vehicles with heat pumps demonstrate 25% to 31% energy savings compared to vehicles equipped with resistive heaters in cold conditions.

Comfort for Drivers and Passengers

A heat pump provides a high level of comfort for drivers and passengers. Thanks to its ability to quickly and efficiently maintain optimal temperature in the cabin, the system creates a cozy atmosphere even on the coldest days.

For electric vehicle owners, the remote heating control function is particularly convenient. Using a mobile app, you can pre-heat the car's cabin before your journey. Importantly, if the vehicle is connected to a charging station, the energy for heating will come from the electrical grid rather than the battery, preserving driving range.

Additionally, the operation of a heat pump is virtually silent, unlike some traditional heating systems, adding to the comfort of using the vehicle.

Quick Cabin Heating

Unlike resistive heaters, a heat pump can achieve a comfortable cabin temperature faster. This is especially important in severe frost conditions when drivers and passengers expect quick heating after entering a cold vehicle.

Systems with heat pumps are optimized for even heat distribution throughout the cabin, eliminating "cold zones" and providing uniform heating of the entire vehicle interior.

Impact on Overall Operating Economy

A heat pump has a significant impact on the operating economy of an electric vehicle:

• Reduced electricity costs: Higher energy efficiency leads to lower costs for charging the electric vehicle.
• Increased range: During winter tests in real conditions, electric vehicles with heat pumps showed a deviation from the official range of an average of 25.4%, while vehicles without heat pumps showed a 33.6% deviation. This translates to additional kilometers of range on a single charge.
• Enhanced energy usage efficiency: Electric vehicles with heat pumps traveled an average of 5.2 km/kWh compared to 4.6 km/kWh for electric vehicles without heat pumps.
• Optimal battery operation: A heat pump can maintain the optimal temperature of the battery (usually within 20-25°C), contributing to its efficient operation and extending its lifespan.

All these factors combined can lead to significant cost savings throughout the vehicle's life, especially in regions with cold climates.

Which Electric Vehicles Have Heat Pumps

Each year, more automakers include heat pumps in the standard equipment of their electric vehicles or offer them as additional options. Here are some well-known electric vehicle models equipped with heat pumps:

• Tesla: Models S, X, 3, and Y are offered with heat pumps. In newer versions, a heat pump is standard equipment.
• BMW: Electric BMW models, particularly i4 and iX, are equipped with heat pumps as standard.
• Porsche: Taycan comes with a heat pump in standard configuration.
• Hyundai/Kia: Hyundai claims to have some of the most efficient heat pumps on the market. Ioniq 5 and Kia EV6 are offered with heat pumps, though not in all trims.
• Volkswagen: ID.3 and ID.4 can be equipped with heat pumps as an additional option.
• Nissan: Leaf was one of the first electric vehicles (in 2012) to receive a heat pump.
• Audi: e-tron models are offered with heat pumps that can be used for both heating and cooling.
• Skoda: Enyaq iV is offered with a heat pump in higher trims.

It's worth noting that the market situation is dynamic, and more manufacturers are striving to make heat pumps standard equipment in their electric vehicles, especially for premium models. The estimated cost of a heat pump as a separate option can range from $500 to $1,000, depending on the model and manufacturer.

Electric Vehicle Heat Pump: Disadvantages and Limitations

Despite all the advantages of heat pumps, they have certain drawbacks and limitations worth considering when choosing an electric vehicle:

• Limited efficiency at extremely low temperatures: At temperatures below -15°C, the efficiency of heat pumps decreases significantly. In such conditions, the system may automatically switch to an additional resistive heater, increasing energy consumption.
• High initial cost: A heat pump is a complex system that increases the initial cost of an electric vehicle. For some consumers, this may be a deterrent to choosing such an option.
• Complexity of repair and maintenance: Systems with heat pumps are technically more complex compared to resistive heaters. They require specialized maintenance and can be more expensive to repair.
• Additional weight and space usage: A heat pump system requires more space and adds weight compared to simple heaters, although modern developments try to minimize these disadvantages.
• Limited efficiency at high temperatures: Similar to extremely low temperatures, at excessively high temperatures (above 40°C), the efficiency of heat pumps for cooling may decrease.

Despite these limitations, the benefits of a heat pump in an electric vehicle typically far outweigh the drawbacks, especially for residents of regions with moderate or cold climates.

Can a Heat Pump Be Added Afterwards?

One question that often interests electric vehicle owners is: can a heat pump be installed in an electric vehicle that wasn't originally equipped with one?

Unfortunately, in most cases, the answer is no. Installing a heat pump after purchasing a vehicle is an extremely complex and usually economically impractical process for several reasons:

• Integration with onboard systems: A heat pump is closely integrated with the vehicle's electrical system, battery cooling system, and energy management software. Installing it after the vehicle's production requires significant modifications to these systems.
• Design constraints: Often, in electric vehicles without heat pumps, there simply isn't physical space to accommodate them without major design changes.
• Lack of official upgrade kits: Automakers rarely offer official kits for such upgrades, creating risks for warranty service.
• High cost: The cost of such an upgrade, even if technically possible, is usually so high that it exceeds economic feasibility.

Therefore, if having a heat pump is important to you (especially if you live in a region with a cold climate), it's better to choose an electric vehicle with this option from the start or opt for a higher trim level that includes a heat pump.

Conclusion

A heat pump in an electric vehicle is not just an additional option for increased comfort but a key technology that significantly affects the energy efficiency and performance characteristics of electric transport. Particularly important is its contribution to preserving range in cold months when traditional heating systems can reduce driving distance by up to 45%.

With a Coefficient of Performance (COP) 3-4 times higher than resistive heaters, a heat pump allows not only saving energy on cabin heating but also maintaining the optimal temperature of the battery pack, contributing to its efficient operation and longevity.

Despite certain limitations, such as reduced efficiency at extreme temperatures and relatively high initial cost, the advantages of a heat pump undoubtedly prevail. That's why more electric vehicle manufacturers are including this technology in the base configuration of their models or offering it as a recommended option.

When choosing an electric vehicle, it's worth paying special attention to the presence of a heat pump, especially if you live in a region with a cool or moderate climate. This investment will pay off through increased range, reduced charging costs, and improved overall comfort of your electric vehicle operation throughout the year.

Each year, heat pump technologies for electric vehicles continue to improve, becoming even more efficient and versatile. The implementation of such innovations is another step towards making electric vehicles a practical and comfortable choice for everyday use regardless of weather conditions and season.