We still have plenty to learn about electric vehicles and how Americans use them since the earliest adopters went green. From the start of 2011 to the beginning of 2014, the U.S. Department of Energy’s Idaho National Laboratory installed over 17,000 level 2 EV charging stations around the country and tracked the charging habits of over 8,000 plug-in hybrid and all-electric car drivers to assess the state of things. The study was the largest on EV infrastructure to date.

Participation from automakers (General Motors, Nissan), charge station providers (ChargePoint, Blink), and car-sharing services featuring EVs (Car2Go) made the data as comprehensive as possible with information coming from each corner of the U.S. To encourage EV owners and businesses to participate, the DOE installed Level 2 chargers in households and company parking lots where it got written consent to monitor use over the three-year period.

As a result, we have the skinny on how 125 million electric miles were driven in the U.S. over three years, ending in 2013. Here are five big takeaways from the largest EV study ever conducted.

1. Most charging away from home happens at work.

If you are a commuter and your workplace has a charging station in the company parking lot, you are in EV heaven. The DOE study confirmed that drivers who had the option to charge at the workplace did so more than anywhere else outside the home. Leaf drivers charge 32% of the time at work and 65% of the time at home; Volt drivers charged 39% of the time at work and 57% of the time at home. It just doesn’t get any more convenient for EV owners.

2. Chevy Volts are matching EVs in electric miles.

Considering the 2013 Nissan Leaf offers 84 miles of range and the 2013 Chevy Volt offers 38, you would expect the pure EV to dominate in the total amount of electric miles covered. However, the DOE study found the number was almost equal for 2012 and 2013: 9,697 miles for the Leaf and 9,112 for the Volt. Looking at the 12,238 average annual miles Volt drivers covered, you see three quarters were on electric power. Plug-in hybrids with significant range are a key tool to reducing emissions.

3. Where charging is fast, public stations are popular.

The study found that DC fast chargers (delivering 80% in 30 minutes) were most popular when located near highway interstate exits. Not only did it encourage EV drivers to go ahead and bring the electric car for a longer trip; it also allowed local drivers to get a quick charge during the day when home or work charging was less convenient. Long charging times are a huge turnoff for auto consumers. Put fast chargers in convenient locations and they’ll see a lot of action, provided the price is right.

4. High charge station fees are limiting EV use.

ChargePoint, owner of the most charging stations, does not set the fees of each location within its network. Therefore, prices range from very low to quite high depending on the whim of the site’s owner. In some cases, these stations are prohibitively expensive and do not see much use. The DOE study showed fast chargers managed by Blink went from frequently used when they started out free to much less frequently used when charges went into effect. If drivers have to pay more to charge their cars than it takes to fill up a car at a gas station, the system breaks down.

5. Public charging is crucial to EV adoption.

As we noticed in our own electric vehicle tests, the “chicken-or-the-egg” conundrum is very much driving EV adoption. The DOE study showed that most people charge at home (and prefer to do so), but the reasons behind that habit are easy enough to gather. People know there will be no competition at home and they can do as they will (i.e., eat, sleep, be with their families) in their comfort zones while the car’s battery gets back to full power.

On the other hand, the lack of public charging infrastructure combined with the low range of today’s EVs is keeping adoption limited. Even when (if) Chevy and Tesla release their “mass-market” EVs, there will need to be a much larger fast-charging and Level 2 charge network for widespread adoption to happen. Otherwise, people will remain hesitant about going electric. They wouldn’t know where to charge in a busy day of driving away from home.

Data source: U.S. Department of Energy

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