Electric vehicles and batteries: how to extend their life (even in the cold)

Batteries have a shorter life in winter - this is evident when we use our smartphones during the cold season. However, this problem can be minimised

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This is not a cliché or merely a theory: in winter, electric cars suffer from loss of range, for a number of reasons, the main one being the actual composition of lithium-ion batteries, which are the most commonly-used. According to a law of physics, as the outside temperature changes, the electrolyte always changes viscosity, i.e. its resistance to deformation. Although each fluid has its own viscosity, temperatures can affect this characteristic considerably: specifically, the electrolyte at 20 degrees has an optimal viscosity for the exchange of lithium ions. When temperatures on the other hand are near zero degrees, the electrolyte becomes much denser and this high viscosity makes the passage of lithium ions difficult. As a result, the battery performance falls below optimal and charging is not at full capacity for the same reasons.

Research by Autobild

The German magazine Autobild decided to study the subject in more detail by considering three important technical studies. The first is a study conducted by Recurrent, an American battery analysis company that examined electric cars in everyday use, discovering the actual loss of range at sub-zero temperatures. There are significant differences between models: the Jaguar I-Pace, for instance, lost only 3% of its range, the Audi e-tron lost 8% and the four Tesla models analysed (Model S, Model X, Model 3 Long Range and Model Y Long Range) showed losses of between 15% and 19%. Other models were found to have their ‘tank' down 30% compared to the total, some down by a maximum of 32% even. An ADAC test confirmed this: a driving distance of 10 to 30% less was determined in the cold, depending on the model, while in the tests conducted by the American Automobile Association, the electric cars tested lost as much as 41% of their range in winter.

Climate control has a lot to do with it

The range was assessed by the AAA also with the heating switched off or on: in the former case, the drop in range was on average 12%, while in the latter the values were very different: between 31% and 50%. The umpteenth confirmation that climate control in the passenger compartment is not a ‘free' service, but on the contrary requires a great deal of energy. On vehicles with a combustion engine, the use of the heating or air conditioning system increases fuel consumption by 5%, while – on average – the range of an electric car is affected by 5% to 10% of the total, constantly using air conditioning. To overcome this problem, several battery-powered vehicles use systems referred to as ‘heat pump' heating systems. These systems do not use an electrical heating element as normal, but instead collect the heat emitted by the engine and electrical systems, returning it ‘at zero cost' to the passenger compartment. This technology means it is possible to reduce the impact of air conditioning to 2%.

Tyres and air

Tyres and air density also play their part. Mandatory (rightly so) by law, winter tyres feature intricately carved treads to fight rain, snow and ice that have a minimum impact on consumption. Hence the winning choice, for electric cars, to fit tyres providing the ideal compromise towards improved rolling resistance. As for the air, in cold weather, it has a higher density than normal and requires additional power to keep the car at the same speed. The resistance to rolling further reduces the range: to a limited extent, but combining this with the energy required for the air conditioning, significant reductions are achieved.

Driving tips

As we await the solid-state batteries that will eradicate these performance inconsistencies (for the same cost and weight, they will have up to 50% more range and a higher charging speed), there are some precautions that can be taken to limit excessive consumption right now. For example, wearing the right clothing, which doesn't mean driving with your coat on, but rather not to exaggerate with the heat setting. One good idea is to choose models with heated seats, steering wheel and windscreen: these often seem like superfluous luxuries, but in fact this system avoids the need to use the heating to demist and remove frost from the windscreen as well as ensuring maximum comfort. Another smart optional: remote heating when the car is charging, so you don't lose a single kW of energy, and set the right temperature. Finally, it is important to drive at optimum speed outside city centres. On motorways, for example, the air resistance at 120 km/h is 15% higher than at 110 km/h.