As the electric mobility space grows, this information becomes more relevant than ever for drivers, manufacturers and the wider Electric Vehicle Charging Market. While the technology on board EVs is becoming more sophisticated at regulating temperatures, weather remains a critical performance factor for drivers on the road.

Why Temperature Matters to an Electric Vehicle

A high-voltage battery pack forms the centre of an EV and is most often comprised of a number of lithium-ion cells. These batteries store and release energy through chemical reactions, and the rate and efficiency of these reactions are determined by temperature.

EVs therefore use thermal-management systems to protect the various pieces of the EV’s electrical architecture from becoming too hot or too cold for operation.

Cold temperatures often have a more direct impact on instant available power and the overall driving range available from the battery, whereas long-term exposure to high temperatures could result in battery degradation over time. Differentiating the two helps understand why an electric car’s driving characteristics can change so dramatically between summer and winter.

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What Happens to an EV in Cold Weather?

Cold weather can decrease the performance of many of the different systems within an EV at the same time. The biggest change that drivers tend to notice first is that the driving range can be greatly decreased.

When a battery is cold, the process of chemical and physical changes is not nearly as efficient. The battery’s resistance is increased, and its cells are not able to provide or absorb power as effectively as they would at a higher temperature. This leaves the vehicle with less available energy as well as less power output than it would normally have.

Research from the US Department of Energy has found that, under controlled test conditions, a battery-electric vehicle’s range can fall significantly at very low temperatures compared with moderate conditions. One study found a reduction of around 41% at 20°F, or approximately -7°C, although the actual effect varies between vehicles, temperatures, driving conditions and heating systems.

This figure should therefore be viewed as an indication of what can happen under particular conditions rather than a universal rule for every electric vehicle.

Why Cabin Heating Uses More Energy in Winter

The main culprits of a fall in winter efficiency are the energy demands of heating the car’s passenger cabin, or “white space,” as it’s otherwise known. Traditional petrol or diesel cars put out a lot of waste heat from the engine, much of which can be used to supply warmth to the passenger compartment. Electric motors are far more efficient and put out little excess heat.

Consequently, the car often needs to take electrical power from its battery to run its internal heating.

Heat pumps, while effective as a way of turning electrical energy into heat while in many circumstances being more efficient than resistance heaters because they move existing heat rather than produce it, still consume power. However, many electric vehicles utilize heat pumps to capture heat from the air outside the vehicle, or from waste heat from other components of the vehicle. This can mitigate the draw upon the battery and keep power consumption from heating to a minimum, albeit heat pumps’ efficiencies also drop in extremely cold temperatures. Two EVs that have identical battery pack capacity will have very different electrical efficiencies during winter months depending on their heating arrangements.

Cold Weather Can Change Regenerative Braking

Regenerative braking converts the kinetic energy of an EV as the motor becomes a generator during deceleration, and feeds it back into the battery. The EV battery may not accept the generated energy at the same rate while very cold as it does at optimum temperature.

As a result, the vehicle’s battery management system is programmed to restrain regenerative braking until the battery is appropriately warmed. In practice, the owner may perceive a difference in the way the vehicle drives in the first part of a journey in extremely cold conditions when the accelerator is released or approaching a junction.

It is most likely a protective feature, rather than evidence of a defect. The battery management system constantly monitors factors such as battery temperature, voltage, current and state of charge; it therefore varies the rate at which energy may be delivered or withdrawn so that the battery operates within a range considered safe.

Once the battery has reached a suitable temperature, normal levels of regenerative braking should be resumed.

Why EV Charging Can Be Slower in Winter

It is also the case during charging that the effects of temperature become noticeable.

A cold battery is not capable of absorbing a large charge immediately; hence, during DC charging, it could reduce charge rates until cells are at optimum temperatures, thereby taking a much longer time to complete a charging session than one at higher temperatures.

Some EVs are provided with preconditioning; this is one technique to deal with the issue of temperature during fast charging. Preconditioning could start before the vehicle reaches the charging point when the sat nav is set to direct to the station, although there are certain criteria for this to occur; for example, the EV will only condition the battery from external sources when on a higher state of charge and also during hotter weather only when appropriate.

The aim is to bring the cells closer to optimal temperatures for higher absorption charge power when connected. The exact operation differs between makes and models of car.

Preconditioning could take place when connected to the mains power; for a combined effect, the traction battery energy could be utilized for cabin heating.

What Happens in Hot Weather?

High temperatures bring about a somewhat similar but different set of challenges.

Heat, unlike the opposite cold temperature condition, doesn’t automatically have as dramatic an effect on how well batteries perform. But there is a higher burden placed on how much energy must be consumed by the car’s active cooling and thermal management system.

Batteries, inverters, motors, and electronic components create heat while operating or charging, and ambient heat causes these elements difficulty in dissipating heat, requiring potentially more activity of cooling components, pumps, fans, or refrigeration-based systems. Also, the active cooling system (Air conditioning)consumes energy directly from the battery, like the resistive heater does when it’s cold,d and a car may utilize its cooling systems for a significant drain on electrical energy, resulting in less energy available for motive force in very hot conditions than when the battery isn’t under unusual stress.

Based on the United States Department of Energy extreme ambient temperature affects range, and this is attributed partly to the fact that the cabin requires heating or cooling, which then results in a requirement of additional battery consumption. The data from that Departmental website for very cold conditions generally show larger percentage reductions in battery capacity than in warm conditions-although each case varies.

How Heat Can Affect Battery Longevity

Perhaps one of the biggest differences to account for is the effect that temperature has on battery degradation over time. When a battery is cold, its performance might be reduced, but many of these performance losses disappear as the battery heats up again. Extended high temperatures accelerate the chemical reactions that degrade batteries,s though.

As battery age is affected by several factors, not least of all is cell chemistry, charging behaviour and so on, temperature is just a part of it, but it is an important one.

Analysis of market trends will give a broader perspective on what is happening, and some organisations will be looking more widely, like Expert Market Research with its analysis of the energy and automotive space and consumer adoption, or Informes De Expertos for market views of innovation in this sector. They bring in broader factors like the charging infrastructure rollout, evolving usage models, or changes in vehicle electrification technologies as they interact with markets.

How Thermal Management Keeps EVs Within Safe Limits

Modern EVs do not leave the battery pack exposed to whatever weather can throw. They take a direct interest in managing temperature. A thermal-management system might try to keep the battery pack warm in freezing weather or to take unwanted heat away when driving hard or trying to charge rapidly.

It may also be responsible for keeping the traction battery and power electronics (which also produce heat and can benefit from careful temperature control) at optimal temperatures and will also control passenger compartment climate.

Keeping even temperature across individual cells within the battery pack is also important, since considerable variations can increase wear-and-tear and degrade battery life. The reason your EV might draw power even when it is parked or connected to a charger is also related to battery temperature control, as electricity would not be used to power the drive motor but rather to set temperature in the cabin or maintain optimal charging range on the battery pack for faster response later.

Temperature Is Only Part of the Range Equation

It might be tempting to blame a fall in EV range solely on weather conditions, but a whole combination of things can have an effect on vehicle energy use simultaneously.

During a winter commute, wet and snowy road surfaces, lower tyre pressure, winter rubber, wind and higher use of heaters and demisters can each add to energy use.

Similarly, during a summer commute, strong air conditioning systems, high solar energy intensity within the cabin and greater demand on the battery cooling systems may add to the vehicle’s energy usage.

Speed is another major contributor. At higher speeds, air resistance rises exponentially, drawing more power to overcome it. Thus, a high-speed motorway jaunt may be significantly more power-sapping even if the day conditions are less taxing – particularly so in harsh weather.

This explains why two journeys in identical external temperatures can yield drastically different efficiency levels.

Improving EV Efficiency During Cold Weather

No one can change the external temperature; however, there are actions available that a driver can implement to minimise its impact:

Preconditioning of the vehicle before departure is likely one of the most effective. If the EV has features enabling remote scheduled heating and/or preconditioning of the battery whilst plugged into a charge the vehicle will draw the energy required from the grid at this point rather than solely rely on the vehicle battery.

There also appears to be value in allowing for larger buffer ranges when taking an extended journey in severe cold conditions; Energy use can be more variable in winter conditions and once below around minus 10C can become harder to predict.

Tyre pressures also require scrutiny; Air pressure falls as temperature drops; over-inflation reduces rolling resistance. Keeping tyre pressures at the manufacturer-recommended levels for winter will be conducive to range.

It may also pay to manage the cabin’s heating. Heated seats/steering wheel can be adequate when there are only occupants present, which in effect avoids having the entire cabin raised to a high temperature.

Drivers may need to factor slower charging rates; as mentioned, a cold battery previously may reduce the charging rate, and planning in a longer pause time at a rapid charger may make journeys more practical in winter conditions.

Managing EVs During Hot Weather

A few prep measures will also help during the summer months.

Parking the EV in a shaded spot or covered area will use less energy to cool down after sitting in the hot sun than if it were parked outside. Similarly, pre-cooling the cabin on the charger will make it less taxing on the traction battery.

During scorching heat, you need to monitor the car’s temperature warning indicators and the way it charges. Modern-day EVs are well protected with control modules that cut the charger speed or the available performance if they heat up. This usually is not due to battery degradation and is a thermal management feature controlling the battery to optimum temperatures.

Does Extreme Weather Make EVs Impractical?

It’s not as straightforward as that.

All forms of vehicle are affected by the temperature. Conventional engines can be less economical in the cold, and their batteries, fluids, tyres, and mechanical components are affected by the outside air temperature.

What an EV driver will find is that this effect is often more keenly felt, as energy in the battery directly influences the vehicle’s range.

EVs today deal with the majority of this via software, thermal-management hardware, battery chemistry, more advanced charging procedures, etc., etc.

The real-world effects also depend greatly on climate. A regular EV operating in a mild environment will probably notice less than an EV that is stored in and driven in sub-zero temperatures throughout the winter, or extreme heat in summer.

What the Future May Bring

Temperature is very likely to continue being another area for future EV progress, too. Battery scientists are looking for battery chemistries and materials that retain more oomph at colder temps; and at the vehicle level, auto companies are enhancing battery heating devices, liquid cooling systems, as well as pump-heat units that repurpose usable by-product warmth. Charging technological innovation is moving alongside these breakthroughs.

Advanced battery pack monitoring programs can regulate temperatures and also various other operating conditions so closely that charging power can easily change to suit the actual conditions.

Yet another possible direction for development lies in improving thermal processes (the systems for warming as well as cooling the vehicle and battery load) – because less electric power is applied for cooling as well as heating the passenger compartments or even the pack, more battery pack electrical energy stays in store intended for powering motors.

Understanding Real-World EV Range

It’s great that there’s an official figure you can compare cars’ ranges against, but it’s only one journey out of millions.

Range isn’t fixed for a variety of factors such as the speed you are traveling at, the road type and traffic you encounter. Even how you drive (including aggressive acceleration, high-speed driving, and sudden braking), what load you have, the tires you use, and even how hot or cold it is outside (which affects how much energy the system uses to run the climate control) all affect your range. Extreme cold or hot weather exacerbates these discrepancies significantly.

So, while using a quoted range figure as an indicator for your EV is helpful for comparisons and estimates in every season, drivers will get a feel for how a certain car performs under their specific, routine driving conditions.

Conclusion

Cold and hot weather have their own issues for electric vehicles, but neither means they are ill-suited to a hard climate. Cold will temporarily cut performance by slowing charging, impairing regen, and reducing efficiency, along with needing more power for cabin heating. High temperatures require higher usage of the cooling system, and repeated periods of very high temps will age the battery slightly faster.

Thermal management is the system that tackles the extremes. Through methods such as a battery heating system, liquid cooling,g and in some cases using heat pumps or intelligently managed charge rates and preconditioning,g these conditions can be largely mitigated to give reasonable performance characteristics within a very large thermal envelope.

The driver’s takeaway should simply be that weather is one of the variables that has an impact on driving performance, along with terrain, distance, speed,d and charging strategies, and that an awareness of all these will allow for more appropriate range calculations and more confident planning.

Author’s Bio:

Roshan Kumar is a technology and mobility writer who explores developments in electric vehicles, battery technology, charging infrastructure and sustainable transport. For readers interested in the broader Electric Vehicle Charging Market, further industry insights are available through industry research and analysis.

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