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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Extreme Temperatures Impact The Performance Of All Types Of Vehicles, To Include All-Electric Cars. Yes Electric Cars Work In The Winter!
Pure electric cars have come a long way, since the introduction of the first-generation all-electric Nissan Leaf (2010). Earlier generation electric cars were usually characterised by limited electric range, and any negative impact on the EV range, made a material difference to the practicality of driving an EV. In particular, the impact on e-range due to cold weather.
Though this subject matter is still relevant, its day-to-day bearing on the latest generation battery-electric vehicles (BEVs) is not quite as pronounced as in the past. The reason is simple: the latest pure electric cars have much larger onboard EV batteries, capable of travelling much further on a full charge. The average size of an EV battery for a BEV is now 60 kWh, with many automotive manufactures offering an onboard EV battery larger than 100 kWh.
A good example is the all-electric Volvo EX90. The electric SUV, has a 111 kWh onboard EV battery with a claimed zero-emission electric range up to 363 miles. The first-generation Nissan Leaf had a real-world electric range lower than 100 miles on a full charge and a mere 24 kWh onboard EV battery. For those new to electric driving, it is worth noting that the real-world e-range will usually be lower compared to the claimed WLTP range published by the EV manufacturer.
The real-world electric range is impacted by a number of factors, to include: temperature, weather, road conditions, driving profile, speed, payload and more! The difference between quoted and real-world electric range could be as much as 25%. In some case, potentially more, and in other case, less.
Back to the weather! The United Kingdom does get cold, but not quite as cold as Norway, Sweden, Finland or even Russia. Across the UK, annual temperatures average a daily high of 14 °C and a low of 6 °C (Celsius). Over England the mean annual temperature at low altitudes varies from about 8.5 °C to 11 °C, with the highest values occurring around or near to the coasts of Cornwall (in the south west).
Yes it is true that these are average temperatures and the northern regions of the United Kingdom, in particular, the highlands experience lower temperatures in the winter, in particular at night. Over Scotland the mean annual air temperature at low altitude ranges from about 7 °C on Shetland, in the far north, to 9 °C on the coasts of Ayrshire and Dumfries and Galloway in the south-west. However, it is fair to say that the UK has a mild climate compared to the above mentioned countries.
Interestingly, Norway, the most matured EV market has an average January temperature of minus 7 degrees Celsius. But that has certainly not reduced the enthusiasm of the country to migrate to zero-emission road transportation. More than 75% of new cars sold in the country are electric.
When it comes to temperature, all types of vehicles are impacted at varying degrees. These include both, internal combustion engine (ICE) vehicles (petrol and diesel) and electric vehicles. For EVs, the cold temperatures has two main negative consequences: reduction in operational performance of the EV and EV battery degradation.
Operational performance mostly impacts the available pure electric range, while EV battery degradation is related to any adverse impact to the integrity and performance of the EV battery i.e. reducing its operational lifespan. It is worth noting that such potential damages will be in extreme artic conditions and not really an issue for us driving in the UK. Moreover the latest-generation of electric cars use lithium-ion EV batteries, which are characterised by high specific energy, high energy density and low self-discharge rate. A lithium-ion EV battery (Li-ion) is quite different and far better compared to the lead acid batteries used in earlier EVs.
In the case of pure electric cars or electric vans, the key temperature threshold is sub-zero (below freezing) temperatures, as this is when the temperature most impacts the performance of a plug-in electric car, like an all-electric Nissan Leaf. Having said that, the performance of an EV can be reduced from below 5 degrees Celsius. Manufacturers continue to find optimal thermal management solutions to better regulate EV battery temperature and reduce any negative impact from lowering temperatures. In general, key areas impacted in electric driving are:
- Battery performance
- Electric car emission-free range
- EV charging speed
- Regenerative braking
Though, there have been some commentators that have suggested that in sub-zero temperatures, the range of a battery-electric vehicle (BEV) is impacted as much as 40%, the majority of the findings suggest an average drop in mileage of 12% (without the use of any services like heating) and up to 25% with the use of services like heating.
In general, an EV battery (lithium-ion) performs best in an ideal range, also known as peak performance. This is no different to any other type of vehicle. When an electric car is out of its ideal temperature range, the EV battery performance is lower because the cold temperatures (sub-zero) or the extreme heat, slows down the performance of the electrolyte fluid within the EV battery cells.
Put another way, in cold weather, the frosty conditions impact the mobility of the electrons within the EV battery. The performance of an EV battery in sub-zero conditions will depend on the type of battery i.e. not all EV batteries are the same. However, in general EV batteries perform their best between 15 degrees Celsius and 25 degrees Celsius.
Apart from the above, in sub-zero or colder driving conditions, it is but obvious to take advantage of heating within the cabin, to include features like heated car seats etc. These services are also powered by the EV battery and therefore an increase in the use of such services will reduce the battery charge available for electric driving.
Cold temperatures also reduce the speed of charging, and depending on the exact conditions, charging speeds can be reduced by 30%. It is also the case that regenerative braking does get impacted in colder conditions i.e. it is not as efficient at recouping energy lost as heat during braking.
In other respects, sub-zero driving conditions impact an EV the same way it impacts an internal combustion engine (ICE) petrol or diesel car i.e. the road surface becomes slippery, and in general driving conditions are more hazardous. Always best to drive with caution and with an appropriate set of winter tyres.
So, if you do live in sub-zero temperatures, we would recommend you to always make sure you have adequately charged the EV battery, and planned your trip to include the potential reduction in performance in emission-free range. Also worth taking advantage of any preconditioning feature to heat the EV cabin while still connected to your home charging point.
Of course, before buying a plug-in electric car, we would encourage you to research in detail the range of the EV, impact of the cold on the specific EV and the overall fit of a potential EV for your needs. The bottom-line is that most of the latest all-electric cars, like to award-winning Tesla Model 3 have a zero-emission range adequate for most commuters between 150 miles to 300 miles (WLTP). The Model 3 has a claimed range up to 374 miles.
We also hope to see new EV battery technology develop further, to include solid-state batteries, which has the potential to perform better than lithium-ion batteries in extreme cold environments. But as mentioned above, we in the UK are fortunate to live in relatively mild temperatures through the year, so for many of us, the issue of sub-zero driving is not as pertinent!
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