INL Releases Massive EV Charging Study

EV charger study released

The Idaho National Lab has completed a massive EV charging study that examines how people actually use public and private chargers to power up their electric vehicles. The results may surprise you.

The generally accepted theory is that the electric car revolution — the event that replaces conventional cars with electric cars forever — won’t happen until there is a public electric vehicle charger on every street corner, just like gas stations. But the study says that theory is wrong. The authors point out that electric car owners can recharge their cars at home and at work, something that drivers of conventional cars can’t do. That one difference changes everything, they say. In the executive summary, the study’s authors write:


The primary question about charging infrastructure placement was: would PEV drivers recharge around town at the nearest charging station, following the pattern they followed with the gas-powered cars they grew up with or would they adopt a new refueling paradigm and charge at the few places where they park their cars for the longest periods of time?

The answer is clear: despite installation of extensive public charging infrastructure, in most of the project areas, the vast majority of charging was done at home and work. About half The EV Project participants charged at home almost exclusively. Of those who charged away from home, the vast majority favored three or fewer away-from-home charging locations, with one or more of these locations being at work for some drivers.

According to, the study looked at several large projects going back to 2009, including the Charge Point America project, Chrysler Ram PEV Demonstration, General Motors Volt Demonstration, South Coast Air Quality Management District/Via Motors PHEV Demonstration, and The EV Project. Between them, they installed about 17,000 charging stations across the US. Data collected from all five projects captured nearly 130 million miles of driving and 6 million charging events, providing the most comprehensive view of PEV and charging usage to date.

The study showed that electric car owners  charged their cars at home 85 percent of the time. When away from home, they tended to favor just a few public charging stations, with workplace stations being most popular. Other factors that drive popularity of public charging locations are community specific. That is, chargers at popular malls where people expect to be away from their cars for an hour or more experience a high number of charging events.

Other unexpected findings from the study include the fact that when privately owned Chevy Volts are charged frequently, they achieved better than 120 mpg in normal use. Also, workplace charging was found to enable significantly more electric range. Project participants with access to charging at work drove 25 percent more on electricity alone than the overall group of vehicles in the project.

In other words, conventional wisdom about how to invest in and build infrastructure for electric vehicles is almost completely wrong. How interesting is that!?


Steve Hanley

Closely following the transition from internal combustion to electricity. Whether it's cars, trucks, ships, or airplanes, sustainability is the key. Please follow me on Google + and Twitter.