It’s definitely winter, and as ever, it’s important to make sure that your car is properly set up for the winter months. For the majority of us, the pre-winter checklist is a pretty obvious one – check your lights, your fluid levels, top up the screen wash and anti-freeze, make sure your tyres are in good nick and maybe pop on some fresh windscreen wiper blades – but what about those of us now driving electric cars?
With the massive increase in electric car sales in 2021 – in fact, at current numbers there are more than 8,000 new electric cars on Irish roads this year so far, and all of them are in their first winter. The big question facing those owners will be: how much will my EV range plummet in the cold weather?
The answer is – it depends. Sorry, but there’s no exact science here, but there are some trends at which we can look. All EVs will have shorter range in the winter, through a combination of the way cold weather affects the battery, to the simple fact that you’ll have the heater turned up higher, for longer.
Battery chemistry
The battery chemistry one is unavoidable, as it’s basic science. While we tend to think of batteries as electrical devices, what they are is chemical devices that generate electrical current. When temperatures get low enough, the physical movement of the chemicals within the battery, which release their electrons to generate an electrical current, slows down and so you get less current. That means you have to dig deeper into the battery for a given performance, and so range duly suffers as you’re drawing more of the battery’s power at a given time.
How much range will you lose? Well, according to the Norwegian Automobile Federation, about 20 per cent. In fact, across 20 of the best-selling electric cars, the average loss of range was 18.5 per cent. Needless to say, though, there's some variation in the figures, and the best-performing cars in the test might surprise you.
The NAF’s test saw each car driven across a multitude of roads, at speeds of up to 115km/h, and in temperatures of minus six degrees Celsius. Each car’s cabin heating system was set to a constant 21 degrees, and if the car had front electric seats, these were switched on in their lowest settings.
The top-performing model was the Hyundai Kona, which lost a mere 9 per cent of its total 449km WLTP official range, leaving it with 405km available on the day. The Audi e-tron quattro SUV lost between 13 per cent and 14 per cent of its range, depending on whether it was the lower-powered 50 quattro or the higher-powered 55 quattro model.
The Tesla Model S lost a big chunk of range – 23 per cent of its total – but with a massive 610km WLTP range, it had performance to spare. The hugely popular Tesla Model 3 Long Range lost a massive 28 per cent of its range, but again, thanks to having a chunky range figure to begin with, it still had a very reasonable 400km left to offer.
The worst performer? Thankfully, it's a car not sold here – the Chevrolet Bolt (tested in its short-lived Opel Ampera-E form), which lost 30 per cent of its range to the cold.
What can you do to help minimise such losses yourself? The best solution is to charge your car overnight, and to use the cabin pre-conditioning system.
According to advice from Renault: "The ability to be able to preheat your electric vehicle is a real bonus: by the time you open the car door, the cabin will already be at a comfortable temperature and, even better, you won't be decreasing your vehicle's range. If pre-conditioning is initiated while the car is connected to a power supply, the energy necessary to heat the interior will come directly from the electricity grid. The range of your vehicle is thus unaffected, allowing you to drive with peace of mind."
It’s not just the cabin heat, though. While the car is connected to a charger, some of the energy coming in can also be used to warm up the battery itself, helping it into its temperature ‘happy place’ and meaning that it will work more efficiently once you start driving.
Renault also advises you to smooth out your driving in lower temperatures: “With the arrival of snow, ice and fog, winter is therefore the perfect time to try out an eco-driving style. The more you avoid sudden stops and starts, the more you will save your battery’s energy. Anticipation will always be your best friend when it comes to a smooth ride and will also reduce your vehicle’s energy consumption.” Good advice all year round, really.
Optimum temperature
According to Charlotte Argue, from vehicle monitoring and telematics service GeoTab, there is an optimum temperature for EV batteries, and right now we’re nowhere near it.
"At optimal temperatures, EVs are performing better than their rated range, peaking at 115 per cent at 21.5C. So, most EV owners are exceeding the rated range of the vehicle in peak temperature conditions. As you turn up or down the temperature, however, the loss of range is apparent. At –15 C, EVs drop to 54 per cent of their rated range, meaning a car that rated for 402 km will only get on average 217 km," said Argue.
“It’s no coincidence that across the board the most efficient trips were taken on days where the average outdoor temperature was 21-22C. This happens to be the temperature at which we humans like to keep our homes. If you get into your car and the temperature outside is below 20C, you are more likely to turn on the heat; above 22C and you’ll probably switch on the AC. Getting the cabin temperature to a comfy house-like condition draws energy from the battery that could have otherwise been used to move the car.”
The best solution for cabin heating once you’re out and on the move is a heat pump, and thankfully more and more EVs now have heat-pump heating systems. A heat pump is more or less exactly what it sounds like. It’s a pump that takes warm air or liquid from a source, and then increases the temperature by compressing it. The increased temperature air or liquid can then be circulated around something that you’re sitting in, be it a car or your house. Basically, it’s like the compressor on your fridge, but working in reverse.
What about getting stuck out there, trying to keep warm? What happens if you’re trundling along happily in your EV, in spite of the cold and the snow, but you come across a monumental tailback, caused by the same snow? Are you going to run out of charge before you get home?
Thankfully, the answer seems to be no. According to consumer group Which?, an average EV has enough battery capacity to last for days when it’s sitting still. Which? simulated tailback conditions with a Volkswagen ID.4 electric SUV, running the air conditioning and stereo (with streaming music), and played a video in the rear seats for one hour, during which time the battery was drained by just 2 per cent. On a full charge of the ID.4’s 77kWh battery, that would mean you wouldn’t run out of power for 50 hours.
