How much do electric cars suffer from the cold?

LET US THINK OF THE BATTERY – L ‘winter it has defeated the most powerful armies, but it also has not insignificant effects in everyday life, for example our car. Those who drive vehicles with internal combustion engines, including hybrids, will see the coolant temperature rise more slowly, and therefore the engine will run for longer at lower than optimum temperatures, with lower efficiency and higher emissions. That electric cars on the other hand, they suffer from batteries whose performance – both by recharging and supplying energy – drops if the temperature is very low, with a drop in‘autonomy and an increase in charging time. The kilometers that can be covered are falling, and so is the performance, but manufacturers have developed various countermeasures.

The most effective strategy, even in terms of duration, is warm up the battery to bring it to temperatures of 20-30 degrees Celsius, but in winter it is not easy: how to find the necessary heat? The efficiency of electric powertrains is very high and therefore the waste heat is low (just think of LED bulbs, lukewarm because most of the energy is converted into light with minimal heat production), as opposed to what happens in internal combustion engines. This is further complicated by the fact that the cabin must also be heated and not just the battery.

MAXIMUM EFFICIENCY – Many builders use one heat pump to warm up the battery and cabin (in the drawing above). This device “carries” the heat instead of generating it. According to Audi, this operating scheme can, for example, generate up to 3 thermal kW from 1 kW of electricity. It is not possible with a few lines to explain how this apparent paradox arises, but we can say that the heat pump takes heat from the outside and transfers it to the liquid that conditions the battery. The paradox is renewed: how to draw heat out of the cold winter air? The temperature difference is exploited: The gas, which is at -50 degrees when circulating in the heat pump, is heated by the outside air, which may be at +2/4 degrees, and when it is compressed it reaches the required 25 degrees. to air condition the battery.

In the case of the e-tron GT quattro and RS e-tron GT, using the e-tron “route planner”, the battery conditioning starts automatically when you arrive at the fast charging station, so charging can take place at high power. There is also a resistance heater for the most demanding situations, which can be further upgraded with an optional set for colder climates. Audi also suggests that planning (via app or on-board systems) it charging and air conditioning of the cabin in advance so that the temperatures are reached by taking energy from the charging point instead of from the battery. It can also be a good idea to recharge immediately before departure, to cope with the journey with the temperatures already at full capacity:energy absorption it is actually maximum (this applies to all electric cars) when the cabin and battery are very cold, but drops so much when the right temperatures are reached.

THE APP THAT WARMS YOU – Similar tips and countermeasures also for Tesla, which says “our preconditioning and scheduled departure functions will help you keep the battery in optimal condition before you start your journey”. Is it possible preheat the car manually by activating preconditioning / defrosting from the Tesla app: The battery and cabin will then reach the correct temperature before the trip starts. The ideal would be to leave the car connected to the mains so that the necessary energy is drawn from the mains rather than the battery. The same function can be automatic by using the programmed start mode, which requires cab and batteries before the departure time.

If the car battery is too cold To harness all the stored energy, the Tesla will show a blue snowflake: Under these conditions, performance will be limited, as will the power of regenerative braking, a different situation that applies to all electric vehicles. Even the navigator of the Tesla can take into account stops to recharge, and precondition the batteries to maximize the speed of refueling; this also applies to non-Tesla charging stations thanks to a 2020 software update.

TRAVEL INFORMATION – The integration with apps is also present, for example, in Mini and BMW cars, which can heat the cabin remotely. This also applies to plug-in hybrids whose battery is capable of operating the heat pump. Even the Bavarian house interacts with the navigator to maximize the recharging speed regardless of the external temperature and the battery. In practice, if there is a stop to recharge, one automatic preconditioning of the battery during the approach to the column. The system takes into account, among other things, the battery temperature, the remaining range, the expected charging power and the course of the rest of the journey.

This preconditioning mode of the battery connected to the navigator, unlike remote ignition via mobile phone, is generally reserved for high-end electric cars, but we have no doubt that it will also expand to the more affordable ones. However, most manufacturers are still watching autonomy simulators which also takes into account the outside temperature, useful tools for understanding how winter can affect the autonomy of an electric car.

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