Running Hot or Cold: A recent study determined extreme temperatures could cut an electric car’s operating range on a single charge by more than half

2014-05-14T06:00:00Z Running Hot or Cold: A recent study determined extreme temperatures could cut an electric car’s operating range on a single charge by more than halfJim Gorzelany CTW Features
May 14, 2014 6:00 am  • 

That was certainly some rotten winter weather we managed to survive, with temperatures plummeting to record lows in many regions and snow falling at least somewhere in all 50 states. And while we’re far from being meteorologists, our instinct says we could be in for a scorching-hot summer as well.

The extreme elements already tend to exact a toll on the average car, but many electric-vehicle owners may feel the worst of it, according to the results of a study conducted by the AAA Automotive Research Center in Southern California. That’s because the results determined an EV’s operating range on a charge could diminish by as much as 57 percent based solely on the ambient temperature.

“Electric motors provide smooth operation, strong acceleration, require less maintenance than internal combustion engines, and for many motorists offer a cost effective option,” said John Nielsen, managing director, AAA Automotive Engineering and Repair. “However, EV drivers need to carefully monitor driving range in hot and cold weather.”

The AAA put three different EVs through their paces under controlled circumstances to gauge how well their batteries fared in stop-and-go-traffic under cold, moderate and hot operating conditions.

According to the results, the three models averaged a respectable 105 miles on a charge at an ambient temperature of 75 degrees. However, this figure plummeted to just 43 miles when the thermometer dipped to 20 degrees. Blistering temperatures had a more moderately adverse effect on the tested vehicles, limiting the average range of the models tested to 69 miles on a charge at 95 degrees.

Note that these fluctuations occur despite the fact that all EVs include provisions to help heat (and/or cool) the battery; usually this is via liquid or forced-air heating and/or cooling.

It should come as no surprise that the biggest draw on an EV battery in cold weather is the cabin heater. While gasoline engines tend to generate large amounts of heat that can be leveraged to warm a car’s interior, an EV must rely on an electric-powered heater to keep a driver’s toes toasty.

Likewise, running the air conditioner when the mercury rises drains an EV’s battery at a higher-than-average rate. Of course one could just wear a heavier coat and gloves while driving and keep the heater switched off in the winter, and forego the A/C in the summer (keeping the windows closed on the highway to maintain the vehicle’s aerodynamics), though neither is a sacrifice most drivers would be willing to take.

According to the MIT Technology Review, thermal storage materials are being developed that can be heated while an electric car is plugged in, then deliver heat for the duration of a drive, though that solution is likely years away for being ready for widespread use. In the meantime, automakers may turn to improved insulation and specific coatings on the windows to help trap heat within the cabin.

While none of us can do anything about the weather, the Environmental Protection Agency says EV drivers can help minimize the adverse effects of extreme weather on their vehicles’ range by following a few simple tips:

• Park the vehicle in a garage to maintain a more amenable temperature. Preheat or pre-cool an EV’s cabin while plugged into the charger to help extend its range.

• Engage the car’s “economy” mode, if so equipped.

• Avoid sudden stops to allow the vehicle’s regenerative braking system to recover additional energy.

• Keep the battery charged whenever there’s access to an appropriate electrical outlet or charging station.

• Run accessories like air conditioning, heating and entertainment systems sparingly; use the seat warmers (if equipped) instead of the cabin heater whenever possible in winter.

Copyright 2014 All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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