Charging EKs on cold winter days is a challenge

As winter approaches, electric vehicle owners face a unique challenge: maintaining the vehicle's range and battery health. After 400 charging cycles, the battery capacity at temperatures below -15°C can be reduced to about 10 percent compared to a new lithium-ion battery. However, most modern EKs are designed to preserve a significant portion of battery capacity even after hundreds of charging cycles.

Cold weather slows the chemical reactions inside batteries, requiring more electricity from the battery to heat. This is less of a concern in warm weather. Driving a car requires much more energy when the battery is cold than when it is warm. Therefore, the effective use of energy in cold weather can be up to 6 times greater per 1 km.

One important precaution EK owners can take to reduce battery damage on cold winter days. Charge the batteries before parking, because in most cases the costs of efficient driving are reduced by charging a hot battery, even if the price of electricity is higher.

Lithium batteries for electric vehicles can become damaged at temperatures below freezing. Storing lithium-ion batteries below freezing temperatures can cause some parts of the battery to crack and separate from surrounding materials, reducing the battery's electrical storage capacity. When the temperature drops low enough, the electrolyte fluid inside the lithium-ion battery cell becomes more viscous, slowing down the chemical reactions that enable the transfer of electrons.

Charging lithium-ion batteries at low temperatures in winter can cause irreparable damage. When charging a lithium-ion cell below freezing temperatures, most lithium ions fail to intercalate (move) into the graphite anode (negative electrode). Instead, they cover the anode with metallic lithium. This is similar to electroplating a coin as an anode using a precious metal as the cathode. Charging will coat the anode with lithium instead of charging it.

When lithium-ion batteries are charged below freezing, the battery capacity is permanently reduced. This damage occurs after an isolated “cold charging” event and is proportional to how quickly the battery charges. Charging a battery below freezing may cause a sudden, severe, and permanent increase in internal resistance. Charging below freezing with an inappropriate charging rate can cause the battery to become less mechanically stable and more susceptible to sudden failure.

These factors affect not only the EK range of each charge, but also how quickly it recharges. To help maintain a good operating temperature, modern EK devices are designed with battery heating and cooling systems. However, these systems use energy to heat the surroundings.

Despite these challenges, advances in EK technology, such as the use of heat pumps and energy recovery systems, are helping to address these impacts. As technology continues to advance, hopefully these winter problems will become a thing of the past for EK owners. Until then, it's always a good idea to check the manufacturer's specifications and tests for more accurate information.