The 2017 Chevrolet Bolt made a splash earlier this year when the car manufacturer announced its 238-mile all-electric range. That number, however, is unlikely to hold up during a New England winter. Studies have shown that the range on battery-powered electric vehicles declines significantly in cold weather.
“In the case of battery electric vehicles, about five degrees Fahrenheit — that’s the bottom-out spot,” says Robert Parsons of the Centre for Emerging Renewable Energy Inc., a Canadian non-profit. “The range flattens out.”
Parsons has conducted studies alongside researchers from Red River College in Winnipeg, Manitoba, on the effects of ambient temperature on battery electric vehicle range and the results have been consistent. The distance they can travel on a single battery charge declines as temperatures grow colder.
In one project, Parsons and others tested the limits of the Nissan Leaf and Mitsubishi i-MiEV in various weather conditions in the Canadian province of Manitoba. The researchers found that the cold weather would typically reduce the range of the BEV to roughly one-third of its maximum distance. The Leaf topped out around 100 miles in ideal conditions, but went just 34 miles in especially cold conditions.
The driving force behind the decline is, according to Parsons and co-researcher Jose Delos Reyes, the comfort of the passengers of the car, not the performance of its battery. Heating the interior of the car’s cabin is the primary stress on battery life in these cold weather situations.
“It’s the thermal management system. It is demonstrably the cabin heating. That’s what is affecting range,” says Parsons. “It is possible that battery capacity can decline in temperature, but in our findings you just don’t see that. Heating the driver and the passenger is demonstrably more significant.”
Passengers, he says, are simultaneously responsible for the decline in range while those same limitations are a primary concern for potential electric vehicle owners.
Confronting range stress
Worries over the range capabilities of electric vehicles, termed range anxiety or stress by experts, are already a significant deterrent for consumers interested in purchasing one. The effects of low temperatures on that range only exacerbate this obstacle.
Thomas Franke, a professor of engineering psychology at the University of Lübeck in Germany, has published a number of papers on this phenomenon. Franke and many others have found that these concerns over limited range are psychological.
“Our results showed that range stress decreases with practical experience and that those drivers who had more actively explored range dynamics ended up experiencing less range stress in daily usage,” Franke says.
Reyes echoes this sentiment: “If you keep using something, you build the operational knowledge of it, the more informed you are. So you can adapt, you can change your driving habits. If the infrastructure is there, you can plan your trips. You can basically avoid the range anxiety issue.”
Even in areas like Manitoba where winter temperatures are frequently cold enough to significantly reduce battery electric vehicle range capabilities, the researchers insist that the vehicles are still worth investing in.
A different view on reliability
Parsons argues that electric vehicles are actually more reliable than traditional ones when the temperature drops. Throughout the study, he found that none of the researchers ever had any issues starting the car, even when the temperature in Manitoba fell below -30 degrees Fahrenheit. He also recalls a time when he drove the i-MiEV on one of the coldest days and drove past two dead conventional cars before arriving at work.
Though this reliability is impressive, the range limitations are serious. Consumers are already wary of electric vehicle range in ideal conditions, which often is just a quarter of traditional vehicles with internal combustion engines. The steep decline in cold temperatures is a serious concern for the electrification of road transport, frequently viewed as one of the primary means of reducing harmful emissions.
Take for example the Nissan Leaf that was tested by Parsons and Reyes. Its 100 mile top end range is enough to meet the needs of most drivers, but when that drops as low as 34 miles, it may fall out of contention for anyone but city drivers. Altough experience with electric vehicles and their capabilities helps assuage such qualms, it will likely take more than familiarity to reach what Franke terms a driver’s “comfortable range.”
Those much needed changes may not be too far off, as evidenced by increasing reang of the Chevy Bolt and other electric vehicles.
“I’m anticipating that in the next 5 years we’ll be seeing new technologies available that improve their range,” says Reyes, who expects a series of incremental improvements over time. “They’re able to make the battery smaller, increasing the capacity without increasing the weight.”
Parsons and Reyes also noted another way to improve the range in cold weather: an auxiliary heater specifically for cabin heating. Since the heating of the cabin is the biggest reason why the range declines, a separate heater would preserve a significant portion of the range lost and could theoretically be powered by clean energy, such as particulate-free ethanol. At the same time, however, this would add yet another thing for the electric vehicle owner to keep track of.
In the meantime, the experts argue that BEVs are worth the investment even with the winter range issues. Drivers simply need to overcome their range stress.
Parson says, “I recommend anyone who gets an electric vehicle: take it out and drive it to dead. Then you’ll be over the fear. Isn’t everyone afraid of running out of gasoline?”