Tesla Technical Director: Improve the insulation of electric vehicles to keep warm

According to Battery.com.cn, at the recent Tesla forum, the impact of winter low temperature on electric vehicle batteries has become a hot topic, and there has been a growing discussion about the impact of cold and cold on the mileage of electric vehicles. But technically, it really has to wait a few years to solve this problem. Although some small flaws can be used to minimize the power consumption caused by low temperatures, it takes at least several years to completely solve this problem technically. In the current situation, even car companies like Tesla and Nissan do not have a two-pronged solution.

In general, there are two factors in the decline of the mileage of electric vehicles in winter: one is due to cold air, and the other is because the heater is turned on when driving in winter, so it consumes a lot of power. If the temperature reaches below zero degrees Celsius, the mileage of the electric vehicle will even be reduced by 30% compared with normal conditions.

The method adopted by Nissan Leaf is a bit "demolition of the East Wall to complement the Western Wall" in Chinese, because the biggest impact of low temperature on electric vehicles is to accelerate the power consumption and increase the charging time, so the Leaf uses a heater. The method is to warm the battery, but this heater is also powered by electricity, so there is not much practical significance. And in fact, using a heater to warm the battery is one of the most important factors leading to reduced mileage. However, Nissan is continually reducing the proportion of this factor. From the recent sales of a heater, the power consumption has reached only 20% of the battery.

Tesla took another approach, using the heat generated by the motor in the car to heat the battery. Although this secondary utilization can improve the efficiency of the battery to a certain extent, this "remaining heat" is limited after all, so it is necessary to let Tesla drive for a few minutes to let the temperature of the car battery reach the normal level. .

The reason why gasoline engines do not exist is because the efficiency of gasoline engines is not high. A large part of the energy generated by gasoline combustion is converted into heat energy, which increases the temperature inside the cabin. However, the efficiency of the electric motor is relatively high, so the excess heat generated is also limited.

In addition, if the temperature of the battery is too low, it will affect the performance of the regenerative braking system. The regenerative braking system uses the power of the brake to charge the battery to improve the mileage. However, if the regenerative braking system inputs too much power to the car battery, it will damage the battery at low temperatures. Therefore, Tesla sets the Model S to work after the battery reaches its normal operating temperature.

Technically speaking, it is also possible to improve the battery performance by reducing the volume of the electrode material composition of the battery, which is equivalent to shortening the moving distance of lithium ions. However, the smaller the volume of the constituents, the higher the chemical activity and the lower the safety of the battery, so additional measures are needed to ensure the safety of the battery. In order to save more energy, the US Department of Energy is also funding the development of thermal storage materials that can be heated while the electric vehicle is charging and release heat when the car is running, but this heat storage material It is not yet available for commercial use.

As for how to solve this problem in the actual situation, Tesla's technical director Straubel suggested that the battery temperature can be increased by setting the time when the car battery is charged, so that the battery is just full before the car is driven. Or, if the car is preheated (controlled by the mobile app) before charging, the battery power consumption can also be reduced. As far as the current situation is concerned, the best solution is to improve the insulation of electric vehicles and use thermal insulation coating to cover the windows to prevent heat leakage inside the vehicle. After all, the space inside the car is not large. Strictly speaking, it does not use much thermal insulation coating.

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