If you own an electric vehicle (EV) and live in a cold climate, you may be concerned about winter charging capacity. But don't despair! Your electric vehicle model is likely equipped with a heat pump, which can help EVs regain between 3% and 15% of the range – up to 50 miles – that would otherwise be lost in cold weather. Heat pumps are an important tool for maintaining the range of electric vehicles.
An engine generates heat during operation; that heat is wasted energy. Internal combustion engine (ICE) vehicles use this excess energy to power a car's heating and ventilation. However, because electric vehicles are much more efficient, their small amounts of wasted energy are not enough to support the ventilation system. In fact, electric vehicles are so efficient that three quarters of their electricity is used to power the wheels. However, this efficiency presents an alternative scenario when the weather turns bitterly cold, occasionally triggering fears of cold climates.
Last week, some electric vehicle owners in Chicago discovered their batteries were dead in freezing temperatures. Other drivers complained that charging an electric vehicle took longer than usual at a few Tesla Supercharger stations. Some chargers did not work at all in freezing temperatures, forcing electric vehicle owners to tow their electric cars.
It's clear that relatively new electric drivers – and perhaps some more experienced drivers who haven't been paying enough attention – needed a primer for using their vehicles in cold weather, such as preconditioning and other workarounds to increase range.
The efficiency of an internal combustion engine vehicle at 20°F in city driving is approximately 15% lower than at 30°C. It can also drop by up to 24% for short trips of 3 to 4 miles. With mixed city and highway driving, EV costs drop by 39%, so it makes sense to optimize your EV's features for the weather, as our CleanTechnica colleague Chris Boylan wrote this week.
Yes, subzero temperatures can have a negative impact on the efficiency of an electric vehicle. In cold climates, electric vehicles consume a lot of energy to heat the passenger compartment. In cold weather, battery capacity may decrease, reducing the average distance that can be traveled on a normal charge. Starting the electric vehicle can also be more difficult in cold weather, as the energy used to heat (and the same applies to cooling in hot weather) in electric vehicles reduces battery charge and mileage, as does turning up the interior heating.
Electric vehicles usually use lithium-ion batteries to power their electric motors. Lithium-ion batteries perform well at temperatures between 50 and 110 degrees Fahrenheit, with a generally accepted ideal temperature being 70 degrees. At sub-zero temperatures, lithium ions slow down and cannot store energy very well. Therefore, they generally perform worse than normal in cold climate conditions.
Still, many electric vehicles have heat pumps that transfer heat from outside the vehicle to divert electricity that could otherwise drain the battery. Electric vehicle heat pumps suck in air, compress it, and then use the heat from the condenser to increase the temperature in either the battery or the vehicle interior. Heat pumps increase the efficiency of an electric vehicle because they transfer heat from existing sources rather than generating it themselves.
Several EV models warm their cabins with resistance heaters, which use electricity to heat wires and then blow air over them. This process drains significant energy from the battery. Electric vehicles equipped with a heat pump can utilize the same efficient process used to warm the interior to precondition the battery.
The coefficient of performance (COP) of a heat pump can reach 3-4 units of heat transferred per unit of electricity consumed. For example, the heat pump is three to four times more efficient than a resistance heater, which converts 100% of the energy into heat. A resistance heater has a COP of 1.
A study from the University of Oxford and the Regulatory Assistance Project used data from seven field studies in North America, Asia and Europe, showing that heat pumps are two to three times as efficient as combustion or resistance heating technology, even at temperatures well below 0°C (32°F). In fact, even at temperatures around -30°C (-22°F), they perform significantly better than their fossil fuel-based competitors.
Which electric vehicles are equipped with heat pumps?
In 2021, Tesla improved the Model Y by installing a new heat pump, resulting in a 10% increase in efficiency. The cooling circuit has been integrated into a single heating and cooling management system for the vehicle, which optimizes the flow of thermal energy throughout the vehicle. Tesla redesigned the heating and cooling systems for the Model Y to take advantage of the inefficiencies of heating and cooling with electricity and to maximize the efficiency of the vehicle's thermal systems.
Tesla CEO Elon Musk explained: “The solution that Tesla’s HVAC team found was a local heating circuit. So the thing basically just spins itself up and gets hot locally before opening another valve which then tries to heat the cabin.”
Heat pumps are essentially air conditioning systems that work in reverse. Heat pumps bring warm air into the car even in sub-zero temperatures. More importantly, heat pumps increase the range of an electric vehicle because they store heat from the batteries.
Which other electric vehicles have heat pumps?
- Jaguar's I-Pace
- The latest i-series cars from BMW
- Hyundai's Ioniq 5
- Audi's latest e-Tron
- Kia's EV9
- Nissan Ariya
- All new Tesla models
Final thoughts on heat pumps
In response to the existential crisis posed by climate pollution, the electrification of personal transport has increased worldwide. Electric vehicles are an important solution to the problems of environmental and energy security.
Heat pumps are increasingly recognized as a critical technology for decarbonization. A heat pump that is designed to operate at low temperatures (which is not the case for all of them) can also function without problems even when the outside temperature is below zero.
In 2022, global sales of heat pumps increased 11%, marking the second year of double-digit growth for the key technology in the global transition to safe and sustainable heating. U.S. consumers installed 4 million ultra-low carbon heating and cooling heat pumps in 2022, surpassing gas furnaces for the first time.
New York State is still digging trenches, laying pipelines and installing equipment, but instead of carrying flammable and planet-warming gas, these pipes will carry water or other liquids that transfer heat from underground – or from other buildings and sources in the network . which can be used by heat pumps to keep buildings warm. It is an example of an adaptation that is redefining the way we use energy, just like the introduction of heat pumps in many electric vehicle models in recent years.
Do you have a tip for CleanTechnica? Do you want to advertise? Would you like to suggest a guest for our CleanTech Talk podcast? Contact us here.
Latest CleanTechnica TV video
I don't like paywalls. You don't like paywalls. Who likes paywalls? Here at CleanTechnica, we implemented a limited paywall for a while, but it always felt wrong – and it was always hard to decide what to put behind it. In theory, your most exclusive and best content stays behind a paywall. But then fewer people read it!! That's why we at CleanTechnica have decided to completely eliminate paywalls. But…
Like other media companies, we need reader support! If you support us, please donate monthly to help our team write, edit and publish 15 cleantech stories every day! AdvertisingCleanTechnica uses affiliate links. View our policies here.