Comparing the Charge Patterns of the Nissan LEAF and Chevrolet Volt
The Chevy Volt and Nissan LEAF are the two best-selling plug-in cars of all time. Released within weeks of one another in late 2010, the LEAF and Volt typify the two categories all modern plug-ins fall into: Plug-in Hybrid Electric Vehicles (PHEV) and Battery Electric Vehicles (BEV). The 2011 Chevy Volt had a 35-mile electric range and an after-incentive price comparable to many luxury sedans, but it offered unlimited range as a 37-mpg hybrid once its lithium ion battery was depleted. The 2011 LEAF started $7,700 less than the Volt and carried a limited, 73-mile driving range.
Despite distinct differences in how the two cars approach electric mobility, a recently released study from Idaho National Laboratory (INL) found something rather surprising: LEAF and Volt drivers travel virtually the same amount of electrically powered miles each year.
(Idaho National Laboratory)
How is this possible given that the Volt’s range is less than half that of the LEAF? The answer lies in the two cars’ distinct usage and charge patterns.
How Much Gas Does the Nissan LEAF Save Compared to the Chevy Volt?
Between 2011 and 2014, the U.S. Department of Energy funded the installation of 17,000 public and private charging stations in 22 regions of the United States as part of the EV Project. More than 8,000 Nissan LEAFs and Chevy Volts participated in the study, which comprehensively logged driving and charge behavior for each vehicle, including how many miles the Volt spent operating in all-electric mode versus hybrid mode.
The DOE found that the Chevy Volt averaged just 6 percent fewer electric miles than the LEAF, and operated outside of EV mode just 25 percent of the time. The Volt travelled an average of 2,541 more total miles than the LEAF—virtually all of them in hybrid mode. So how did LEAF and Volt drivers get roughly equivalent electric-only usage out of their cars?
Charging Frequencies of the LEAF and Volt
Though a fully-charged LEAF starts out with more than twice the electric range of a fully-charged Volt, INL found that Volt drivers charged their cars 36% more frequently than LEAF drivers.
LEAF owners typically charged their cars overnight at home. Most consumers who opt for a LEAF know that their daily needs will usually fall within the car’s range limitations. This means many LEAF owners typically have little motivation to plug in during the day. They know they have enough range to get back home, where they can charge overnight during off-peak utility hours.
Volt owners often have the opposite incentive. After their limited electric range runs out, their cost-per-mile skyrockets as the car burns gasoline in hybrid mode. This helps to explain why Volt owners plug their cars in an average of 1.5 times per day compared to 1.1 charges per day for the LEAF.
Where do the LEAF and Volt Charge?
The vast majority of plug-in vehicle drivers do nearly all of their charging at home. Overall, the cars in the DOE survey used home charging more than 85 percent of the time. Roughly half of drivers relied on public or workplace chargers for less than 5 percent of their total use. One fifth of the vehicles in the study accounted for 75 percent of away-from-home charging.
(Idaho National Laboratory)
More LEAFs (13 percent) charged exclusively from home than Volts (5 percent). A relatively small portion of total charging was done using public charge stations. Overall, 98 percent of charging took place at a home or workplace.
(Idaho National Laboratory)
Plug-in drivers tended to cluster their charge events to just a few select stations, with 92 percent of Volts and 77 percent of LEAFs using three or fewer charge locations over the course of the study. Those who used five or more charging stations tended to be LEAF owners, many of whom occasionally rely on public charging in order to make it home after an unusually long trip.
Volt owners were far more likely to plug their cars into standard outlets for a Level 1 “trickle charge” away from home. Roughly half of outside charging for the Volt came from standard outlets.
Meeting the Charging Needs of Today’s PHEVs and BEVs
Since the EV Project’s data was collected between 2011 and 2014, the vehicles it studied have improved. The 2016 Chevy Volt boasts an electric range of 53 miles—a whopping 51-percent improvement over the 2011 model. The 2016 LEAF offers optional ranges of 84 miles or 107 miles, depending on how much battery a buyer wants to pay for. So how will charge behaviors to be affected by increasing ranges for both BEVs and PHEVs?
First, we can expect modern PHEVs like the Volt to pass BEVs like the LEAF in annual electric mileage. The average daily use of vehicles in urban areas is just 36.5 miles, and rural cars average less than 50 miles per day. Increased BEV range will give drivers the freedom to take the occasional longer trip, and give more buyers confidence that their needs can be met by a limited-range plug-in. But on the whole, most LEAF owners won’t regularly use the extra range offered in the 2016 LEAF and their electric miles are unlikely to increase dramatically.
Plug-in hybrids already yield nearly as many electric miles per year as BEVs that carry more than twice as much battery capacity. Volt drivers tend to log about one-third more total miles than LEAF owners, according to the INL study. A 42-percent range increase means that more of those extra miles will be driven in EV-mode.
Home charging will continue to be central to the charge balance as battery ranges increase. Drivers already do the vast majority of charging at night, and with utilities moving to incentivize off-peak charging, plug-in owners will take advantage of lower home rates whenever possible.
Expanding public charge infrastructure—including rapidly growing fast-charging networks—will give drivers greater freedom on days they actually need to add range to complete their trips. Public charging is unlikely to represent more than a small fraction of total charge usage for the foreseeable future, but the DOE study confirmed that pricing schemes and location can greatly impact usage.
Chevy Volt and Nissan LEAF owners drive and charge their cars at least somewhat differently in nearly every area measured in the INL study, but what unites them is a desire to avoiding using gas. In order to provide infrastructure and services to support their needs, governments and private companies will continue to study these drivers’ habits. The EV Project provided us with our first comprehensive glimpse of real-world EV usage in the U.S., but its findings only represent the first step towards optimizing the charging landscape to facilitate plug-in adoption and better serve drivers.
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