E-Mobility & E-fuels

E-Mobility on trial: batteries in winter

posted on 5/27/2022

Winter is gearing up. For users of e-mobility and those who think about switching, it’s supposedly not the best time of the year, but why? Many myths and misunderstandings surrounding electric cars have their cold grip on people’s views. We’ve talked tech, trends and truths with BMW e-mobility expert Wieland Brúch, to clear some of them.

This is the season when e-mobility horror stories of halved reach, icy cold interiors and endless loading times are circulating the media – not the ideal circumstance to warm people up to e-mobility. “Rumours like these are a big concern for many people, mostly because they lack first-hand experience with e-mobility,” says Wieland Brúch from BMW.

It shows, that even in these digital times, information sometimes travels slowly. Many facts about e-mobility, especially concerning the use in winter, simply aren’t true anymore. They might have been 5 or 10 years ago, but the technology is continuously evolving. “We observe that the energy density of batteries doubles about every five years,” Brúch notes – meaning that there are often rather large leaps in performance, a feat which isn’t necessarily publicly noted.

Myth no. 1 – reach is halved

One of the most persistent claims from sceptics is that electric vehicles suffer from approximately 50% less reach in winter. This has been true for some of the early models, but has long since been fixed. What is still true though, is that low temperatures affect the battery just like they do most machines and materials. During particularly cold weather the electrolyte in the battery gets more viscous. Simply spoken this means that ions can’t travel as fast from one battery pole to the other, resulting in less voltage, which consequently results in a higher power consumption and, in theory, less reach. Battery heating systems, which are the standard for most newer models, effectively protect the battery from getting too cold and prevent them from consuming too much energy. So, is reach affected at all? This brings us directly to myth no. 2.


Myth no. 2 – you mustn’t heat the car during the winter

Heating consumes energy, which means there’s less power left for driving. Brúch explains that: “Electric cars are, by design, more efficient in terms of propulsion then conventional cars. This is due to less heat waste. Conventional cars use this wasted heat to warm the interior. For e-cars, heating has to be produced purposefully.” The solution to this is not to keep gloves and hat handy, but to heat more efficiently. One very good method is to preheat the car while it’s charging. There’s usually a mode for this and often even an app, with which you can control the automated process. This way, the energy for the heating comes directly from the source and not from the battery. Plus, you get to board an already warmed up car without harming the environment and don’t need to worry about clearing ice from the windows. If you want to use the heat whilst driving, it’s best to use the seat heaters. “The seat heating utilises power very efficiently. You get a good level of warmth inside the car with a comparatively low use of energy. This is definitely the better alternative to the classic fan heaters.” And if you happen to like it really toasty whilst driving, the share of energy that heating takes from the battery is quite low these days. “With a practical reach of about 260km, the initial heating up generally eats up about 6–8km, so only 3% of the total reach, depending on the car model.”


Myth no. 3 – charging time drastically extends in winter

“Modern electric cars can take in the 11kWh from the wall-box at home or public power stations up to temperatures of -10°/-15° C without any problems or delay. Cold weather only plays a role with quick charging stations, because the battery needs to have a certain temperature to charge effectively. But as soon as you plug the car in, the battery will acclimatise itself,” Brúch remarks. To ensure optimal energy intake, it is recommended to charge the car after driving or keep it in a garage.


Myth no. 4 – e-cars brake less effectively in winter

Modern e-cars use a system called regenerative braking, an energy recovery mechanism which converts the energy required to decelerate a car into a form that can be reused either immediately or stored for later. In electric vehicles, regeneration also means that taking your foot off the accelerator immediately decelerates vehicles, a factor which is affected by the cold. This, however, has no effect whatsoever on the performance of the actual brakes. It simply means that there might not be the same amount of energy gained from the braking process as under normal circumstances.


In the end, it’s about attitude

With some of the most common myths busted there is not actually much, that separates e-cars from conventional ones when it comes to performance in winter – not to forget that any car might experiences difficulties in dire weather. Thus, welcoming e-mobility is more about adapting one’s mindset. A clear example of shifting attitudes can be seen in Norway. The Scandinavian country, which is known for its cold winters, is actually one of the most developed countries in the world when it comes to e-mobility. “Norwegians have long since learned to plug in their cars, even the petrol models, to keep the engine warm in cold weather,” the expert explains. Charging e-vehicles was not much of a novelty to them and hence not much of an issue, providing a glimpse into what e-mobility could become elsewhere in the world.


Where does the journey lead?

With technology evolving, the winterhardiness of e-cars is going to improve even further. “Heating is always going to influence the battery as it’s a fixed energy consumer, but with growing reach and battery capacity it is going to be of less and less importance for the overall performance,” Wieland Brúch states. Even today, with small changes in behaviour, e-driving can be as enjoyable in winter as throughout the rest of the year. “In the early days, e-mobility was only attractive for a very specific group of people. Today, with better technology and more possibilities, it might not be the optimum solution for everybody yet, but surely for more and more.”

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