Are electric vehicles good in the winter?

In less than three weeks we will officially be in winter and EV drivers might ask whether electric vehicles are the best choice for the cold months.

December 1st marks the start of the UK winter, lasting through February and we know it can more than a little chilly at times. Luckily, given our temperate island climate, there are few places where it gets very cold.

Very cold weather affects every form of driving, as we most likely have experienced in our lives – the pure joy of an internal combustion engine refusing to start on a dark freezing morning.

The physics of car batteries means that all are affected by drops in temperature so let’s a have look at what an EV driver would be up against with winter weather in the UK, while having some sympathy for the fossil-fuel driver more likely to face problems starting when the cold snaps bite.

EV extremes

Night temperatures rarely drop below −10 °C (14 °F) or rise above 15 °C (59 °F) in the daytime for most of the UK but in the really tough areas, like the Scottish Highlands, the Pennines and Snowdonia the average lowest temperature each year can be between 17.7 and −12.3 °C (0.1 and 9.9 °F). The lowest temperature ever recorded in the UK was −27.2 °C (−17.0 °F) way back in 1982.

Now, that’s nothing compared with what drivers have to contend with in places like Canada, but even there the EV is a sound choice, managing to cope with extreme conditions, like temperatures going below -36C.

Simon Blaaser, EV charging product specialist at SaveMoneyCutCarbon advises:

“All our car batteries are not really equipped to deal with low temperatures and work best when it’s 15C to 26C. As the temperature drops, the electrolyte fluid inside the battery cells is more sluggish so you will find that they drop in capacity by about 20% in freezing weather, and this is even more pronounced in extreme conditions. For example, the battery capacity will be around 50% less when it drops to around -30C.

“So that’s why the standard petrol or diesel vehicle will likely be hit by battery problems on a frosty morning. That’s because of reduced capacity and increased draw from starter motors that draw a huge amount of energy, along with the need to power vehicle accessories.

“But the design of an electric vehicle means that it can cope better with icy conditions. The large lithium battery should provide the power to start in more or less any cold weather but it’s also true that, like traditional batteries, its performance is affected. With a bit of forethought and agile planning, this should never be a terminal problem.”

New EV habits

If it turns very cold, some studies show that EV battery performance dips significantly. A Nissan Leaf tested in extreme conditions had a decrease in range of around 25% at -15°C, and about 45% when the temperature dropped to -25°C. Comparable models currently on the market show similar results.

Given the general UK climate, this drop in performance is probably going to be rare and even so, the reduced range is higher than we’d normally need, bearing in mind that the average car journey is 6½ miles and the average distance travelled during the day is 22 miles.

Even so, EV drivers acquire new habits in cold weather, as this affects charging times, and the internal comfort also needs a proactive approach.

Simon Blaaser advises:

“The internal combustion engine produces its own heat, which warms the engine and the car interior, but the EV needs to generate this in other ways, from drawing a small amount of heat the motors and inverters generate or with a heater. This means there’s less power to drive the wheels.

“But the good thing is that most EVs now have a pre-heating function to warm the interior while the car is still plugged in, and you can switch this on through a remote button on the key fob or via an app on your mobile phone. When you’re ready to roll, you’ll use far less of your charge to maintain the internal temperature.”

Longer charge time

It’s also true that colder batteries take longer to charge, adding up to an extra hour or two to the overnight charge, although this would not apply if the EV is charged in a warm garage, while a rapid charge at a motorway service station could take 45 minutes instead of 30.

Combined with the shorter range and the opportunity for pre-heating the car on their return, many electric car owners take every opportunity to plug their cars in during the winter months, both at home and using public charging points. For typical day-to-day driving, opportunity charging has a mostly psychological benefit for owners, but at least they know the car is available to use whenever they need it.

As the battery is the most expensive component on an EV, Simon warns that the EV’s onboard computer could limit how it is used in those rare very low temperatures.

“For example, Tesla Model S drivers are advised that some stored energy may be held back if the battery is too cold  and the company has a snowflake icon next to the range indicator to show that there might be an adverse effect, maybe around 20% fewer miles than in normal conditions.

“A top tip for EV drivers is to make sure you always have a charge of at least 20%, which will be enough to get you going in sub-zero temperatures.”

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