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Weather cuts range for new-energy vehicles

Hu Yumo
The driving range of electric vehicles in winter has become a concern for new-energy vehicle owners with industry insiders pointing out that charging is also affected.
Hu Yumo

The driving range of electric vehicles in winter has become a concern for new-energy vehicle owners.

Industry insiders pointed out that not only the battery performance will be affected by temperature, but the charging speed of electric vehicles will also be correspondingly limited due to the low temperature.

Dai Kangwei, vice president of BAIC Electric Vehicle Engineering Research Institute, said in a media interview that the decline in the battery life of electric vehicles in winter is closely related to the principle of charging and discharging power batteries.

Dai said that when temperature is low, conductivity of the material itself will be worse, which could affect the battery performance and capacity volatilization.

In addition to the performance of the battery, air conditioner inside the vehicle is also a big power consumption in cold winter.

Gu Feng, an engineer for air conditioner and vehicle thermal management of BAIC, gave an example that when a test vehicle is tested at minus 7 Celsius degrees, air-conditioning power consumption generally accounts for 20 percent to 25 percent of the total vehicle power consumption.

Dai said that the heat source of air-conditioning system of gasoline vehicles comes from engine. The conversion efficiency of the engine is 40 percent for power, and the remaining 60 percent of heat conversion can fully meet the air-conditioning and heating needs of driver and passenger.

However for electric vehicles, all the energy required for heating must be obtained from the battery. The use of air-conditioning systems has become the main source of electric vehicle power consumption in winter.

When the air-conditioner is first turned on, the power of air conditioner is relatively high which is the most power-consuming time. After the temperature stabilizes, the power consumption of the air conditioner will be greatly reduced from the beginning.

For low temperature these days in Shanghai, Zhang Xiaofeng, an independent market analyst, said that new-energy vehicles have passed the extreme cold test and there is no problem with short-term low temperatures in Shanghai.

Auto companies have been working on technical research to improve battery performance in winter.

With the development of electric vehicle technology, many low-temperature improvement technologies are being researched and advanced, including improving the conductivity.

For low-temperature battery performance degradation, a common practice in the industry is to heat the battery through heating system to keep it in a normal working state and maximize battery charge and discharge as well as effectiveness.

Chinese electric vehicle startup NIO said that their electric vehicle owners could start the battery pack preheating remotely on mobile app, so the battery life and performance are well guaranteed in cold weather. NIO said heating in advance can improve battery efficiency and help to enhance the overall performance of the vehicle, such as acceleration and maximum speed.

The solution given by WM Motor is to install a diesel heater on a pure electric vehicle. The working method is similar to that of a water heater. The liquid in the pipe is heated by fuel combustion, allowing the battery pack to adapt to different environmental temperature ranges, maintaining stability and ensuring that the battery is in the best temperature range during charging and discharging. Meanwhile, diesel heater also makes the cockpit warmer, reducing the energy consumption of air conditioning in winter. 

Increasing the battery performance, improving the efficiency of air-conditioning heat pump and other measures are also the main technical methods for car manufacturers to continue to optimize the driving mileage in winter.

For new-energy vehicle owners, Dai Kangwei suggests that parking inside the building and turning on the power recovery mode to increase the cruising range when driving. The owner can choose to charge in time when the driving is over and the battery has residual temperature to increase the charging efficiency.

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