What is the risk of electric cars in case of high temperatures?

It’s hot, very hot even right now in France. And it is not without consequences for electric cars. Air conditioning, battery, autonomy: We will review the few points to check its electrical model in case of a heat wave.

As you probably know, France is currently facing a heatwave. This episode occurs early in the year and unfortunately 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 gripping areas can sometimes even exceed 80 degrees. In this oven we all have the same reflex: turn on the air conditioning. Some fairly newer models even have the benefit of quick access with a “cool the cabin” feature to quickly bring the temperature down. Most electric cars are connected and the air conditioner can be controlled remotely using apps. But as we will see, high temperatures also affect elements other than the cabin, especially for electric cars.

What are the risks of the battery?

Batteries must remain within a temperature range specific to each model to ensure proper operation and durability, often around 25 degrees Celsius. Batteries heat up quickly when charged at high power and run at high speed. Therefore, the importance of a high-performance cooling system is not to feel a loss of power, both of the electric motor and that of recharging.

Tesla, Hyundai, Kia, Audi, Porsche and other Jaguars that are entitled to a fluid circuit do not really suffer from heat problems, except perhaps with really intensive use, such as. on the field. However, at high temperatures there is no risk of loss of power or deterioration of the cells.

For other models, such as Renault Zoé, Nissan Leaf or Volkswagen e-UP, the battery temperature is regulated by means of forced ventilation. This is a cheaper system than liquid cooling, but it is so less efficient. Some users have seen the operation of their car temporarily deteriorate when the battery temperature exceeds 45ºC. This results in a loss of power when accelerating or a battery not recharging as quickly as expected. In the worst case, it can even break down the battery cells if the high temperature is maintained for extended periods.

But in most cases, the car will manage on its own to regulate the current (in charge or while driving) at the level of the battery to avoid any deterioration of this. So you can use your car normally, but do not be surprised if you notice a drop in current when charging in direct sunlight on a car that has not been cooled by a fluid system.

Can charging at public terminals be affected?

Generally exposed to direct sunlight, charging stations are filled with electronic components. Although well insulated from the outside most of the time, the operating temperature of a charging station fluctuates between -25 to +45 degrees according to the technical data of the manufacturers.

A threshold that is sometimes reached or even exceeded in case of high temperatures. The charging effect can thus be changed. Several members of our editorial staff have come across this case. Especially at Tesla on v2 Superchargers, where the terminal went to safety, at 60 kW, after a few minutes of charging. Putting a damp cloth on the plug made it possible to find the maximum effect. A problem never encountered on Superchargers v3. We have also had the case on various “local” networks, with direct current fast terminals in direct sunlight, unable to exceed a few kW of power when they simply did not fail: the electronic control system can trigger a safety measure to prevent overheating of the terminal . Thus, the recharging operation will be interrupted before it is completed.

Ideally, to avoid this type of phenomenon, the charging stations should be protected from the weather, as is done on some charging stations, with a roof that protects against rain and sun.

What impact on autonomy?

If the cold has a real influence on the autonomy of electric cars, high temperatures do not have the same influence in advance. At least that is what we have observed during our numerous electric car tests conducted for several years now, and in all kinds of weather.

In fact, if the temperatures are high, you will need air conditioning. And it will actually have an impact on autonomy as the system draws electricity from the battery to function. Electric cars nevertheless have an advantage: A large number of models are equipped with a particularly economically reversible heat pump system. Unlike thermal vehicles, there is no need to “let the engine run” 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 which are therefore dependent on a resistance to heat the cabin in winter as on internal combustion engines) are still equipped with a heat pump heat for cold production. An air conditioner thus uses about 1 kW per. operating hour compared to about three times as much for heating a vehicle equipped with an electrical resistor.

To save a few precious miles of autonomy, do not hesitate to enable air recycling. As a general rule, air conditioners operate with a power of 1 to 2 kW and cause a car to lose between 15 and 25 km of autonomy, depending on the model. Must be compared with the heating in winter, which can go up to 3, even 4 kW in 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 hit by very hot weather. Tesla then warned its customers that it was best not to charge their car at certain times due to the heat wave and local energy constraints. And this problem could be set to multiply with successive, increasingly intense heat waves.

The inhabitants try to adapt to this heat as best they can, especially with air conditioning, but these units are particularly consuming and thus overload the electricity grid. Gov. Gavin Newsom had also urged Californians to limit their use of household appliances between 6 p.m. 15.00 and 22.00, so that the state can meet the high energy needs.

Message from Tesla in case of a 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 “if possible” reduce the charging of their electric car between 1 p.m. 16.00 and 21.00. The announcement also warns that public services may also cut off power in certain areas to prevent possible forest fires that could affect certain Superchargers.

Nothing to worry about in France

In France, Tesla has not yet had to send such a message to its customers, as the French power grid is much more reliable and robust than its American counterpart. Especially since the French are not particularly equipped with air conditioning. Peak consumption on the French network occurs in winter, with peak consumption almost doubling in summer depending on the year. However, it is necessary to qualify because certain nuclear power plants (those cooled in an open circuit on a watercourse) in case of high temperatures throughout the territory may be forced to slow down their reactors if the temperature in their watercourses becomes too high . This would reduce the country’s electricity production.

To summarize whether high temperatures can have an impact on electric cars and the charging infrastructure, it depends primarily on the car and the terminal used. On a daily basis, you should not feel any major differences when using your electric car, but if you are planning a long trip with charging at regional express terminals, then plan a little more autonomy to be prepared. a charging station that is out of order or very slow.

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