Extreme Weather Affects An Electric Car's Range
(Inside Science TV) – The looming question on every electric car owner's, or prospective owner's, mind is: How far can you go on a battery charge?
The answer might depend on whether you live on the balmy California coast or in parts of the freezing Midwest.
Researchers at Carnegie Mellon University in Pittsburgh, Pennsylvania looked at data from drivers of the 2012 and 2013 Nissan Leaf and weather information in their area to learn how extreme hot or extreme cold days affect electric vehicles' performance.
"What we were interested in this study was the factors that can affect the efficiency of the vehicle, which include the climate or the temperature, how that would affect the range efficiency and emissions of that vehicle," said Jeremy Michalek, a mechanical engineer at Carnegie Mellon.
What did they find?
"Electric vehicles on average consume about 15 percent more energy per mile when they're driven in an extreme weather region like Phoenix or Minneapolis … that means if they're consuming more energy that they will have a lower range," explained Michalek.
It gets worse.
"In fact, during peak days where the temperature is at its extreme, the range could drop by 40 percent or more," said Michalek.
Basically what that means is "a vehicle that normally gets a hundred-mile range, it would only get 60 miles on this extreme weather day," he said.
That could add a bump in the road to your travel plans.
"If you wanted to drive from D.C. to Baltimore and back, on a normal day you could do that in an electric vehicle, but on an extreme weather day you might not be able to make the whole trip, you might have to stop and charge and that might take hours," said Michalek.
An important factor that influences battery life is temperature. Batteries are less efficient in extremely cold conditions and degrade more quickly in very hot conditions. Plus, cranking up the heat or air conditioning uses even more energy and drains the battery.
But there's things drivers can do during extreme weather days.
"One of the biggest factors is the use of heating and air conditioning to keep the cabin comfortable. So, if you reduce the use of heating and air conditioning then you can maintain a longer range," said Michalek.
"Using electric seat heaters might help you not need to keep the air in the cabin quite as warm because you're warm, you're being heated, so some strategies like this can help reduce the energy needed to keep passengers comfortable, and then extend the range of the vehicle," he said.
Researchers only looked at data for the Nissan Leaf. However, they expect the weather effect to be similar for other electric vehicles. Even they were surprised by the findings.
"We expected temperature would have an effect, that's why we got interested in the study, but we didn't really know the magnitude of the effect and I think the magnitude is a little bit surprising," said Michalek.
So, if you're thinking of taking a long journey with an electric car, you might want to check the weather first.