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The Next Big Challenge for Electric Cars: Cold Weather

If you own a Chevy Volt or Nissan Leaf, your cell phone will deliver information on your state of charge, and also something else you might need -- the weather report.

If the mercury is dropping, drivers of electric cars need to be ready to lose some range. I drove both cars during the recent East Coast cold snap, and both suffered significantly.

Why cold does electric vehicles no good
Two factors reduce range in electric cars when it gets cold: batteries are less efficient, and the heater turns out to be a very big power draw. The Leaf has a very effective dashboard display that shows current demand from various accessories, and in the cold, the draw from the climate system can exceed that of the electric motor under light load.

It was in the 20s and 30s when I had both cars. Spending four days with the Volt, which has a 25- to 50-mile all-electric range, I found I was consistently getting near the lower end of that range (28 miles was average).

In the Volt, according to the car's line director, Tony Posawatz, electric range is determined by an algorithm that takes into account recent driving experience. Since I cranked the heater in "comfort" mode, it accurately predicted how far I'd go. Of course, the Volt seamlessly starts the gas engine when the all-electric miles run out, so it's not that big a problem.

Volt owners have the option of using the "eco" climate mode, which saves battery power by favoring the seat heaters over the power-draining electric heater. My car didn't have seat heaters, so "eco" in that case throttles down the fan and makes other power-saving moves. As a Volt-owning poster named Micro Chip said on the GM-Volt.com, "In Eco mode, I'm cold."

Life lessons from the Leaf
Meanwhile, the Leaf's touted 100-mile range proved illusory. The car originally calculated range at 106 miles, but after a 20-mile up and back trip in the cold, with the heater set at 75 degrees, the in-car range was dialed in at 55 miles.

Nissan's Steve Oldham says that the Leaf hasn't been delivered on the East Coast yet, so much of the cold weather performance is preliminary. But people who have leased BMW's Mini E electric car report a similar drop to approximately 65 miles from 100 in the winter. The company tells customers, "Your driving habits and patterns and accessory use (including heat and a/c) and outside ambient temperature all play a role in driving range." Indeed they do.

Nissan is upfront about the fact that the Leaf's range depends on driving conditions. In a series of scenarios for U.S. driving the company put out last year, range varied from 138 miles with 38-mph cruising at 68 degrees to 62 miles in 14-degree weather with the heater blasting in stop-and-go traffic. There is also an "extreme case" of just 47 miles in really horrible weather conditions outside the U.S.

Felix Kramer, founder of CalCars.org, owns both a Volt and a Leaf. He lives near San Francisco, so cold weather isn't as big an issue, but on a recent run to snowy Lake Tahoe in the Volt he chose "eco" mode and got 38 miles of electric range. "I don't mind wearing a jacket in the car," he said. In normal driving of the Leaf around San Francisco, Kramer reports getting range in the upper 80s.

Go west, electric car
The cold-weather issue of battery cars is one reason (among many) that much of the early volume is likely to be in warmer states, most prominently California (which could see half the total rollout).

EV companies and battery producers are fond of pointing out that consumers don't need as much range as they think they do. "The average commuter travels 35 to 40 miles a day," said Charles Gassenheimer, the CEO and chairman of Indiana-based battery company Ener1. "Range anxiety is overplayed," he added. Maybe not when, baby, it's cold outside.

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Photo: Jim Motavalli