It seems EV drivers who get free fast charging are taking full advantage of it.

Those that fast charge for free stay plugged in nearly twice as long as those that pay, according to the U.S. Department of Energy (DOE). Analysis of data from 2.4 million charging sessions over a three-year period, from Jun. 30, 2020, to Jun. 30, 2023, showed that the average paid charging session lasted 42 minutes and consumed 22 kwh of energy. The average free charging session was one hour and 18 minutes, and consumed 42 kwh.

The data is based on the EVWatts dashboard, a DOE project managed by Energetics consulting and using a self-selected subset of EV owners, aiming at better understanding charging patterns. It now includes data from 50,712 charge ports, 14.16 million sessions, and more than 249 terawatt-hours of energy.

The results might not directly suggest that the cost is what keeps people plugged in longer, but it does underscore that congestion can be more of an issue when charging is free—or when owners might be charging to a higher level than they need. Tesla for instance recently has added a “congestion fee” aimed at boosting throughput at busy charging stations.

The EV models that offer unlimited fast-charging are limited, though. The Lucid Air gets it for two years on Electrify America, and the Nissan Ariya and the Toyota bZ4X get it for a year on EVgo. Also the BMW i7 offers unlimited Electrify America charging for three years. Otherwise, for the most part, free fast-charging offerings are capped at 30 minutes per session. 

2023 Toyota bZ4X at EVgo charging station

It doesn’t cost a lot to charge an EV. And it’s worth noting that gas vehicles cost up to six times more to keep filled, compared to EV charging for the same mileage.But in some regions electricity costs may be enough to influence those with free fast-charging to stop and plug in their vehicle instead of charging at home—particularly during electricity price hikes.

Other owners may simply have a low level of awareness about home charging possibilities, and might not be charging at the rate they potentially could. A 2021 J.D. Power study found that many EV owners were unaware of charging options, as well as potential incentives for installing a charger at home.