The e-zoomed FAQ series: brief responses to pertinent questions related to driving an electric car! If you have a question, simply email us at shop@ezoomed.com!
Electric Cars: The Basics
For those of you new to zero-emission electric driving, we recommend a read of the following articles:
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What Is A Heat Pump In Electric Cars?
There are two keywords that begin with the letter ‘E’ in electric driving. Yes, the first one is ‘electric‘, but equally important is ‘efficiency‘. Since the introduction of modern electric cars, automotive manufacturers have been working hard in developing technology for electric vehicles (EVs), to enhance vehicle efficiency and improve electric range.
A good example of technology (innovation) that improves efficiency in electric cars, is regenerative braking. Also known as regen braking or brake recuperation, regenerative braking is a process of capturing the wasted energy (during braking) from an electric vehicle, to be re-used (recycled). In the case of electric driving, the ‘captured’ energy is reused to increase the pure electric range of the EV.
Heat pumps for electric cars is another ‘efficiency enhancing’ innovation fast gaining acceptance by automotive manufacturers. At the core, it works on the same principle as regenerative braking, in that, it captures ‘waste energy’, to be re-used (recycled) for improving e-range. We can continue to expect automotive manufacturers to develop new technologies based on ‘recycling’, as any form of transport will always have inefficiencies (waste) that can be re-used!
A heat pump is not a new technology and in fact, similar technologies have been used for several decades, in particular, in home appliances, like the ubiquitous refrigerator (similar, but in reverse). However, in relation to electric cars, it is relatively new, with the Japanese automotive manufacturer Nissan to become the first to incorporate a heat pump in a battery-electric vehicle (BEV) in 2012, the all-electric Nissan Leaf.
EV manufacturers gained significant insights early in the evolution of modern electric cars, in particular, related to the onboard EV battery performance and real-world electric range. It became clear that the impact of extreme temperatures (hot and cold) had a material adverse impact on the performance of the onboard EV battery and the available e-range. In particular, during the colder winter months. The genesis of the incorporation of a high efficiency heat pump is a result of such insights.
EV Heat Pump: The Basics | |
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What is a heat pump in electric cars? | In conventional internal combustion engine (ICE), petrol and diesel vehicles, the energy (waste heat) generated from the engine (powertrain), is captured to re-use for heating the interior cabin of the vehicle. However, in pure electric cars, the heat generated (waste heat) from the electric drive (electric motor, inverter, on-board AC charger) and the onboard high-voltage EV battery is not as much, as the heat generated in conventional cars, and cannot be re-used on its own to provide sufficient cabin heating (electric cars are more efficient than petrol/ diesel cars). Therefore in EVs, the sources for capturing heat, also includes the outside air i.e. it is a multi-source heat pump system. This captured heat is re-used for the onboard EV battery management and also for heating the cabin interior, increasing the electric car efficiency and reducing the need to draw energy from the onboard EV battery. In general, a lithium-ion EV battery is less energy efficient during colder months (similar to the laptop or smartphone battery). |
How does a heat pump increase electric range in colder winter months? | Electric cars that do not incorporate an onboard heat pump, rely on the energy of the onboard EV battery for heating the interior cabin of the electric car, further impacting the available e-range. In contrast, EVs with a heat pump, do not rely on the onboard EV battery to heat the cabin. Instead, the heat pump sources heat from multiple sources and releases energy-efficient heating into the cabin. Put another way, an electric car with a heat pump does not place any demand on the onboard EV battery for heating the interior cabin. There is ample real-world evidence to prove that electric cars with a heat pump offer longer electric range in winter months, compared to electric cars that do not incorporate a heat pump. The average improvement in range is between 10% to 20%. Put another way, cars with a heat pump average 3.2 miles/ kWh, compared to e-cars with not heat pump (2.9 miles/ kWh). |
How does a heat pump work in an electric car? | Step 1: naturally heated antifreeze is channelled into the heat pump evaporator, where the heat is transferred to the coolant circulating in the unit. The evaporator converts the coolant into gas (evaporation). Step 2: the gas is sucked into a compressor to increase the pressure of the gas. When air is compressed it increases its temperature. The gas temperature is increased to 80° C. Step 3: the compressed gas is transferred to a condenser, where the heat is transferred to water in the condenser. Step 4: the heat is then circulated to the interior cabin, while the gas is converted into liquid form, and is transferred back to the heat pump evaporator via an expansion valve. The cycle is then repeated. |
Is a heat pump used only for heating? | No. A heat pump can also be used for cooling. As an example, the Audi Q7 EV uses the onboard heat pump for heating and cooling. |
Does a heat pump come as standard in EVs? | Though some manufacturers offer the heat pump as standard, most offer it as an optional extra. We recommend purchasing the option. |
Can a heat pump be installed in an electric car post delivery? | Usually it is not possible, given the complexity of installing a heat pump. So always order it at the time of purchase. |
Are all heat pumps in electric cars the same? | No. There is a difference in technology, approach and efficiency achieved for different manufacturers. As an example, Hyundai and Kia claim to have one of the most efficient heat pumps, given the ability of their technology to dynamically choose the most appropriate heat source at a given moment. Hyundai claims the heat pump incorporated in the all-electric Hyundai Kona can improve the winter electric range up to 18%, significantly higher than the average improvement (10%). |
Are there any other advantages offered by a heat pump in colder months? | Yes, you can pre-heat the electric vehicle (EV) via your mobile app before you commence your journey. This way you can have a toasty warm interior cabin on a cold winter day! |
Examples of electric cars with an on-board heat pump |
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Audi Q4 e-tron |
Hyundai Kona Electric |
Hyundai Ioniq 5 |
Mercedes EQE SUV |
Nissan Leaf |
Tesla Model Y |
Volkswagen ID.3 |
Volkswagen ID.4 |
Volkswagen ID.5 |
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