It is not a cliche, but above all a question of batteries. In winter, electric cars suffer from a reduced range for various reasons. Premise: the most frequently used battery packs in the car industry exploit an essential component, the cell, where the battery charging and discharging cycles take place. Each cell contains the anode, the cathode, a circuit that connects the anode and the cathode and a fluid, the electrolyte where the lithium ions are immersed. These are responsible for the energy exchange. According to a law of physics, as the temperature changes, the electrolyte changes viscosity, i.e. its resistance to deformation. Although each fluid has its own viscosity, external temperatures can affect this characteristic considerably: specifically, the electrolyte at 20 degrees has an optimal viscosity for the exchange of lithium ions.
Cold and charging
When temperatures are approaching 0 degrees, the electrolyte becomes much denser and this high viscosity makes the passage of lithium ions difficult. As a result, the battery efficiency drops by up to 15-20 percent compared to the optimal value. Charging is equally detrimentally affected for the same reasons. If we connect the electric car to the current at low temperatures, the viscosity of the electrolyte will slow down the charging speed. This is why an increasing number of zero-emission models are equipped with air-conditioned batteries, which are cooled in summer (excessive heat also adversely affects electrolyte viscosity) and heated in winter. Then there are models which, once a charging dock has been set into their sat-nav, activate a battery pack heating system so that the cells can ‘prepare' for a more efficient charge.
Air conditioning
These issues are compacted by other obstacles which are common to cars with a combustion engine, starting with the air conditioning of the passenger compartment, something that does not come ‘free of charge'; on the contrary, it requires a lot of energy. On diesel or petrol vehicles, 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 between safety and rolling resistance, such as the Pirelli Elect. 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.
Very useful options
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. According to a study by the German ADAC, air conditioning an entire passenger compartment requires between 2 and 5 kW of energy, whereas heating all five seats, the steering wheel and the windscreen uses up just 150-200 W. Another smart option: 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.
