What are the risks of electric cars in case of high temperatures?

It’s hot, very hot even right now in France. And this is not without consequences for electric cars. Air conditioning, battery, autonomy: we are going to review the few points to check on your electric model in the event of a heat wave.

As you are surely aware, France is currently facing a heat wave. This episode happens at the beginning of the year and, sadly, it comes back more and more regularly. Extreme heat has a significant impact on our cars, especially electric ones.

In a car, the heat is uncomfortable, and the temperature in the cabin can easily exceed 50 degrees. Some exposed surfaces and grip areas can sometimes even exceed 80 degrees. In this oven we all have the same reflex: turning on the air conditioning. Some fairly recent models even benefit from quick access with a “cool cabin” function to quickly lower the temperature. Electric cars are, for the most part, connected and climate control can be managed remotely thanks to to applications. But, as we will see, high temperatures also affect other elements besides the passenger compartment, especially in electric cars.

What are the risks of the battery?

Batteries must stay within a specific temperature range for each model to ensure proper function and durability, often around 25 degrees Celsius. Batteries heat up quickly when charged at high power and driven at high speeds. Hence the importance of a high-performance cooling system so as not to notice a loss of power, both from the electric motor and the recharging motor.

Teslas, Hyundais, Kias, Audis, Porsches and other Jaguars that are entitled to a liquid circuit don’t really suffer from heat problems, except perhaps during really heavy use, like on the circuit for example. But during high temperatures, there is no risk of power loss or cell deterioration.

For other models, such as the renault-zoe, the nissan leaf or the Volkswagen eUP, the battery temperature is regulated by forced ventilation. This is a less expensive system than liquid cooling, but then it is less efficient. Some users have temporarily affected the operation of their car when the battery temperature exceeds 45ºC. This results in a loss of power when accelerating, or a battery that doesn’t recharge as quickly as expected. In the worst case, it can even degrade the battery cells if the high temperature is maintained for long periods.

But in most cases, the car will manage, on its own, to regulate the power (loading or running) to the level of the battery to avoid any deterioration of the battery. So you can use your car normally, but don’t be surprised if you notice a drop in power during fast charging in direct sunlight in a car that isn’t liquid-cooled.

Can recharging at public terminals be affected?

Generally exposed to direct sunlight, charging stations are full of electronic components. Even if they are well insulated from the outside most of the time, the operating temperature of a charging station fluctuates between -25 and +45 degrees according to the technical data provided by the manufacturers.

A threshold that is sometimes reached, or even exceeded, in the case of high temperatures. The charging power can thus be altered. Several members of our editorial team have come across this case. Specifically in Tesla in the Superchargers v2 where the terminal entered security, at 60 kW, after a few minutes of charging. Putting a damp cloth on the connector allowed to find the maximum power. A problem never found in Superchargers v3. We have also had the case of several “local” networks, with fast direct current DC terminals under direct sunlight, unable to exceed a few kW of power, when they simply did not fail: the electronic management system can activate a measure of safety to avoid overheating in the terminal. Thus, the recharge operation will be interrupted before its completion.

The ideal way to avoid this type of phenomenon is that the charging stations are protected from the elements, as is done in some charging stations, with a roof that protects from the rain and the sun.

What impact on autonomy?

If the cold has a real impact on the autonomy of electric cars, high temperatures do not, a priori, have the same impact. In any case, this is what we have observed during our numerous tests of electric cars carried out over the past several years, and in all weather conditions.

Actually, if the temperatures are high, you will use the air conditioning. And indeed this will have an impact on range as the system draws electricity from the battery to function. However, electric cars have one advantage: a large number of models are equipped with a particularly economical reversible heat pump system. Unlike thermal vehicles, it is not necessary to “leave the engine running” and consume a large amount of energy to generate cold air. Note, however, that electric cars that are not equipped with a heat pump for heating (and therefore rely on a resistor to heat the cabin in winter like internal combustion engines) are still equipped with a heat pump. . Therefore, an air conditioner consumes about 1 kW per hour of operation compared to about three times more to heat a vehicle equipped with an electric heater.

To save a few precious kilometers of autonomy, do not hesitate to activate air recycling. As a general rule, the air conditioning works at a power of 1 to 2 kW and causes the car to lose between 15 and 25 km of autonomy, depending on the model. To compare with the heating in winter that can reach 3, even 4 kW in the case of a resistance. With the presence of a heat pump, we return to values ​​close to air conditioning.

When Tesla takes the lead

In 2020, California was affected by very hot weather. Tesla had then warned its customers that it was better not to charge his car at certain times due to the heat wave and local energy limitations. And this problem could multiply with successive increasingly intense heat waves.

The inhabitants try to adapt to this heat as best they can, in particular with air conditioners, but these devices consume a lot, thus overloading the electrical network. Governor Gavin Newsom also asked Californians to restrict appliance use between the hours of 3 pm and 10 pm so the state can meet high energy demand.

Tesla message in case of heat wave in California
The message displayed on Tesla screens in California // Source: unequal_equilibrium on Reddit

For its part, Tesla had also participated in the “collective effort” by sending a message to its vehicles asking drivers to reduce “if possible” the charge of their electric car between 4 and 9 p.m. The message also warns that utilities may also cut power to certain areas to prevent potential wildfires, which could affect some people. superchargers.

Nothing to worry about in France

In France, for the moment, Tesla has not yet needed to send such a message to its customers since the French electricity grid is much more reliable and robust than its American counterpart. Especially since the French are not very equipped with air conditioners. The maximum consumption in the French network occurs in winter, with a maximum consumption almost doubled in summer depending on the year. However, it is necessary to qualify because in the event of high temperatures throughout the territory, certain nuclear power plants (those that are cooled in an open circuit over a water course) could be forced to slow down their reactors if the temperature of their water course raise too much. . This would reduce the country’s electricity production.

In short, whether high temperatures can have an impact on electric vehicles and charging infrastructure depends mainly on the car and the terminal used. On a day-to-day basis you shouldn’t feel any big difference when using your electric car, but if you’re thinking of a long trip with recharging at the regional fast terminals, anticipate a little more autonomy to be prepared. a terminal that is out of order or very slow.

In California, Tesla is warning customers that it’s best not to charge their car at certain times due to the heat wave and local power limitations. A problem that could…
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