The AAA sent out a new press release today warning about the effects of extreme temperatures on electric vehicle range. The numbers are kind of astounding: "nearly 60 percent lower in extreme cold and 33 percent lower in extreme heat." Wow, right? Well, sort of.
The AAA ran a simulated EV test using a dynamometer and a climate-controlled room set for three temperatures: cold (20 degrees F), warm (95) and hot (105). In the tests, the "average EV battery range" for the three temperatures was 43, 69 and 105 miles, respectively. While we certainly agree with the AAA that EV drivers need to recognize that range will drop in the winter, there's more to the story.
The image above shows the distances driven in my personal 2007 Honda Fit after four different tanks. I took the top two pictures last summer, when it was warm, and the bottom two in February, when it was most decidedly not. The tanks on the left were when I was driving normally and the ones on the right were where I was much more careful, shifting to N and coasting long before coming to a stop and accelerating slowly, for example. In the worst case, my roughly 9.5 gallons took me just 310 miles. In the best, 384, a 74-mile per tank difference. These were not scientific tests, but are enlightening nonetheless and show that temperature and driving style affect all cars, not just EVS.
The image shows the distances driven in my 2007 Honda Fit after four different tanks.
You can test this out in your own car, no matter what the powertrain. The EPA also has a helpful resource about Fuel Economy in Cold Weather for gasoline and hybrid vehicles. The upshot is that a decrease of about 12 percent is common for gas cars (at 20 degrees F compared to 77 degrees) and about 32-33 percent for hybrids. The EPA also explains why cold weather impacts your efficiency, and some of the reasons do not apply to EVs:
So, yes, make sure you've got enough juice in your battery to get home this winter. It's just as important as making sure you've got enough gas.
"Engine and transmission friction increases in cold temperatures due to cold engine oil and other drive-line fluids.
It takes longer for your engine to reach its most fuel-efficient temperature. This affects shorter trips more, since your car spends more of your trip at less-than-optimal temperatures. ...
Colder air is denser, increasing aerodynamic drag on your vehicle, especially at highway speeds.
Tire pressure decreases in colder temperatures, increasing rolling resistance.
Winter grades of gasoline can have slightly less energy per gallon than summer blends.
Battery performance decreases in cold weather, making it harder for your alternator to keep your battery charged. This also affects the performance of the regenerative braking system on hybrids."
New study conducted by the AAA Automotive Research Center shows electric vehicle driving range can be nearly 60 percent lower in extreme cold and 33 percent lower in extreme heat.
ORLANDO, Fla., March 20, 2014 /PRNewswire-USNewswire/ -- Electric Vehicles (EVs) are energy efficient and environmentally-friendly with the added benefit of reducing fuel costs for motorists. But, just as motorists need to know how far the gas in their tank will take them, EV drivers need to be aware of how far their vehicle can travel on a single charge. According to new AAA research conducted with the AAA Automotive Research Center in Southern California, electric vehicle range can be reduced by an average of 57 percent based on the temperature outside.
"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."
To better understand the impact of climate on electric vehicle batteries, AAA conducted a simulation to measure the driving range of three fully-electric vehicles in cold, moderate and hot weather. Temperature made a big difference in driving range for all three EVs.
Vehicles were tested for city driving to mimic stop-and-go traffic, and to better compare with EPA ratings listed on the window sticker. The average EV battery range in AAA's test was 105 miles at 75°F, but dropped 57 percent to 43 miles when the temperature was held steady at 20°F. Warm temperatures were less stressful on battery range, but still delivered a lower average of 69 miles per full charge at 95°F.
AAA performed testing between December 2013 and January 2014. Each vehicle completed a driving cycle for moderate, hot and cold climates following standard EPA-DOE test procedures. The vehicles were fully charged and then "driven" on a dynamometer in a climate-controlled room until the battery was fully exhausted.
AAA has initiated several projects including mobile recharging units and EV charging stations to support members who drive electric vehicles. EVs provide owners with many benefits, but every motorist needs to be aware of conditions that can impact vehicle driving range. EV drivers need to plan carefully in hot and cold weather. Mapping tools such as the AAA TripTik® Travel Planner pinpoint charging stations to keep motorists on the go.
Additional information regarding AAA's electric vehicle testing is available on the AAA NewsRoom.
As North America's largest motoring and leisure travel organization, AAA provides more than 54 million members with travel, insurance, financial and automotive-related services. Since its founding in 1902, the not-for-profit, fully tax-paying AAA has been a leader and advocate for the safety and security of all travelers. AAA clubs can be visited on the Internet at AAA.com.