EV charging in cold temperatures could pose challenges for drivers

July 31, 2018

New research from Idaho National Laboratory suggests that electric vehicle drivers could face longer charging times when temperatures drop. The reason: cold temperatures impact the electrochemical reactions within the cell, and onboard battery management systems limit the charging rate to avoid damage to the battery.

The new study, which looked at data from a fleet of electric vehicle (EV) taxis in New York City, was posted last week by the journal Energy Policy.

"Battery researchers have known about the degradation of charging efficiency under cold temperatures for a long time," said Yutaka Motoaki, an EV researcher with INL's Advanced Vehicles research group.

But most of the current knowledge comes from experiments with smaller batteries in the lab, not data from large, electric vehicle batteries in real-world conditions. Further, EV manufacturers often provide consumers with only rough estimates of charging times, and they typically do not specify the range of conditions for which those estimates apply.

"We wanted to ask the question: What is the temperature effect on that battery pack?" Motoaki said. "What is the effect of degradation of charging efficiency on vehicle performance?"

Motoaki and his colleagues analyzed data from a fleet of Nissan Leafs operated as taxis over roughly 500 Direct Current Fast Charge (DCFC) events. Temperatures for the charging events ranged from 15 to 103 degrees Fahrenheit.

The researchers found that charging times increased significantly when the weather got cold. When an EV battery was charged at 77 degrees, a DCFC charger might charge a battery to 80 percent capacity in 30 minutes. But at 32 degrees, the battery's state of charge was 36 percent less after the same amount of time.

And, the more the temperature dropped, the longer it took to charge the battery. Under the coldest conditions, the rate of charging was roughly three times slower than at warmer temperatures.

It's important to note that cold weather would only impact EV drivers under specific circumstances, Motoaki said. For instance, people who charge their EVs in a warm garage and use their EVs for commuting within the range of their battery might not experience much inconvenience. Decreased fuel economy in cold weather is also a well-known phenomenon with gasoline and diesel-powered vehicles.

But time spent charging in cold temperatures could make a big difference for a taxi driver, since every minute spent charging a vehicle is a minute the driver is not making money.

"There's a lot of uncertainty about what the vehicle owner's experience would be if they drive the vehicle in Maine or Michigan," Motoaki said.

The research poses questions not only for EV customers, but also for utilities and charging infrastructure providers. For instance, the location or abundance of charging infrastructure may need to be different in colder climates, and electric utilities might see electricity use vary as the seasons change.
-end-
Funding was provided by the U.S. Department of Energy (DOE) Vehicle Technologies Office (VTO).

For more information about electric vehicle research at INL, visit https://www.inl.gov/research-program/transportation-transformation/.

Idaho National Laboratory is one of DOE's national laboratories. The laboratory performs work in each of DOE's strategic goal areas: energy, national security, science and environment. INL is the nation's leading center for nuclear energy research and development. Day-to-day management and operation of the laboratory is the responsibility of Battelle Energy Alliance.

See more INL news at http://www.inl.gov. Follow @INL on Twitter or visit our Facebook page at http://www.facebook.com/IdahoNationalLaboratory.

DOE/Idaho National Laboratory

Related Data Articles from Brightsurf:

Keep the data coming
A continuous data supply ensures data-intensive simulations can run at maximum speed.

Astronomers are bulging with data
For the first time, over 250 million stars in our galaxy's bulge have been surveyed in near-ultraviolet, optical, and near-infrared light, opening the door for astronomers to reexamine key questions about the Milky Way's formation and history.

Novel method for measuring spatial dependencies turns less data into more data
Researcher makes 'little data' act big through, the application of mathematical techniques normally used for time-series, to spatial processes.

Ups and downs in COVID-19 data may be caused by data reporting practices
As data accumulates on COVID-19 cases and deaths, researchers have observed patterns of peaks and valleys that repeat on a near-weekly basis.

Data centers use less energy than you think
Using the most detailed model to date of global data center energy use, researchers found that massive efficiency gains by data centers have kept energy use roughly flat over the past decade.

Storing data in music
Researchers at ETH Zurich have developed a technique for embedding data in music and transmitting it to a smartphone.

Life data economics: calling for new models to assess the value of human data
After the collapse of the blockchain bubble a number of research organisations are developing platforms to enable individual ownership of life data and establish the data valuation and pricing models.

Geoscience data group urges all scientific disciplines to make data open and accessible
Institutions, science funders, data repositories, publishers, researchers and scientific societies from all scientific disciplines must work together to ensure all scientific data are easy to find, access and use, according to a new commentary in Nature by members of the Enabling FAIR Data Steering Committee.

Democratizing data science
MIT researchers are hoping to advance the democratization of data science with a new tool for nonstatisticians that automatically generates models for analyzing raw data.

Getting the most out of atmospheric data analysis
An international team including researchers from Kanazawa University used a new approach to analyze an atmospheric data set spanning 18 years for the investigation of new-particle formation.

Read More: Data News and Data Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.