winter driving - by flickr user Hey PaulEnlarge Photo
Is it really all doom and gloom for electric car owners when winter weather comes, and will electric car owners be stranded in the snow as many columnists have suggested? That's the suggestion we've seen time and time again over the weekend as another band of heavy winter storms is poised to hit already frozen states from Illinois and Oklahoma through to the eastern seaboard.
We've already proven that the 2011 Tesla Roadster Sport 2.5 can cope with moderately cold weather without range loss, but what about other cars and colder temperatures?
Fist, we should point out that very low extremes of temperature will drastically affect every car, including electric vehicles. For an electric car a lot of this energy is lost due to a lack of thermally managed battery packs, unheated overnight storage, how the car is used during the day, and the use of cabin heaters.
2010 Tesla Roadster Sport 2.5 Cold Weather TestingEnlarge Photo
Liquid Thermal Battery Management
Liquid thermal battery management can keep electric car battery packs at optimal operating temperature to ensure optimal range regardless of the weather by heating or cooling the battery pack as required.
But not every electric car uses liquid thermal battery management, something Tesla’s CEO Elon Musk has been very keen to point out in the past when mocking rivals’ electric cars.
Why did Musk rant? Nissan and Mitsubishi, unlike Tesla, Coda, Ford and Chevrolet, does not use liquid heating or cooling in their respective 2011 LEAF and 2012 i electric cars. Without heating to keep the battery packs warm in very cold weather the internal resistance of the packs will increase, reducing the amount of high-current power that can be withdrawn from them and ultimately, limiting range.
Bear in mind, however, that a car with a liquid heating system for the battery will use that system to keep the battery pack warm when the car isn’t being driven. Leaving the car outside and unplugged will affect your range, as energy from the battery pack is used to keep itself warm.
To avoid adverse mileage in cold weather in an electric car with thermal management of the battery pack, ensure it is plugged in whenever it is not in use.
In general, the coldest weather tends to happen at night. For most electric car owners, that translates to the time when their electric cars are charging in a garage, parking lot or other covered area.
Being in a garage helps keep the battery and car at a warmer temperature, meaning that in the morning the batteries are generally warmer than they would be if the car had been stored outside.
Since the battery will generally stay warm while the car is being used due to the heat generated as the chemical energy storage of the battery is turned into electrical energy, the battery pack should remain reasonably warm and responsive as long as the car is being used.