Electric vehicle owners reported a loss of range of as much as 30 percent when the polar vortex swept through the Midwestern and Northeastern states in late January. The reason is that lithium-ion batteries are generally most efficient at about 70 degrees. While it varies from vehicle to vehicle, operating in subzero temperatures can cut range by as much as half. There are a variety of technical reasons why battery cars routinely deliver less range in extreme weather conditions. These include the extra power required from the battery to either heat or cool the cabin, or to defrost the windows, or to heat the seats. Also, the battery charges more slowly in cold weather. Even in optimum weather, lithium-ion batteries lose about one percent of range every day. The fix may come with the next generation of electric vehicle batteries, which are expected to improve performance, although “solid state” batteries are not expected to be mass produced until 2022 or later.
While electric vehicle batteries are referred to as “lithium-ion,” they are composed of over a dozen compounds that contain different formulations of materials such as cobalt, iron, and manganese. These materials respond to temperature in different ways. Batteries can overheat and damage their chemistry and shorten their life. At colder temperatures, the internal components of a lithium battery become more resistant to passing current. The flow of energy is reduced and capacity is lost.
Also, the battery pack contains hundreds of individual battery cells and they are designed differently by the various electric vehicle manufacturers. The Nissan Leaf uses a simple and relatively inexpensive air-cooling system. The I-Pace, Tesla Model 3, and many other electric vehicles rely on more expensive liquid-cooled systems. A disadvantage with this type of system is that they use more energy on their own, especially on very hot or cold days. On the plus side is that these liquid-cooled battery packs can remain closer to their optimum operating temperature.
Conditioning the Battery
Most battery electric vehicles can be “preconditioned” when they are plugged into a charger. That means a motorist can start warming the vehicle’s cabin before they leave home or office, saving a few kilowatts of battery power since the energy comes from the grid. Some owners find that this improves a car’s range on a frigid morning by about 10 percent. But, it is not only the amount of energy stored in the battery pack that is impacted by cold weather.
Conventional hybrids like the Toyota Prius, plug-ins like the Chevrolet Volt, or a pure battery electric vehicle like the Nissan Leaf use regenerative braking to maximize range. Where normal brakes slow a vehicle by friction, turning energy into heat, regenerative brakes are small generators where the kinetic energy gathered when slowing down is turned back into electric current and returned to the batteries. Those brake generators lose efficiency when it gets very cold, thus also reducing consumers’ expected range because of less on-board generation. This is a “double whammy” for electric vehicle owners in cold conditions.
Next Generation Batteries
The prospective next-generation batteries are known as “solid state” or “lithium-air,” which will replace the liquid slurry inside lithium-ion cells with a solid ceramic material that is expected to speed up charging, improve range, reduce costs, and better handle cold temperatures. These next-generation batteries have been demonstrated so far only in the research laboratory. Some energy experts predict solid-state batteries will be ready for production by 2022, while others expect that date to be closer to the end of the decade.
Tesla’s Door Handle Problem
Tesla Model 3’s handles are flush with the exterior of the car and require customers to push on one side, then pull on the other to open them. Ice makes opening those car doors difficult for drivers. The owners have tweeted solutions and Elon Musk tweeted last month that Tesla was preparing over-the-air software updates that would improve how its cars were holding up in cold weather.
Electric vehicles have a range problem compared to internal combustion engines, which is made worse when temperatures are frigid. During the polar vortex, electric vehicle drivers lost about 30 percent of vehicle range due to the cold weather. Pre-conditioning a vehicle can help with that problem, but it is more likely to be fixed by the next generation of battery technology, whenever that emerges.