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Study Shows California Charging Stations Operationally Deficient


  • More than 27% of the San Francisco Bay Area's EV charging stations are not functioning properly.
  • The survey found drivers of electric vehicles facing issues such as unexpected shut-offs and broken plugs during charging as well as payment problems.
  • The study examined 657 charging plugs at 181 public stations in nine Bay Area counties.(Not including Tesla charging stations.
  • David Rempel, a retired bioengineering professor at the University of California, Berkeley, and volunteers with Cool the Earth, a nonprofit, spent two minutes at the stations to check for operational problems.

Study Abstract

In order to achieve a rapid transition to electric vehicle driving, a highly reliable and easy to use charging infrastructure is critical to building confidence as consumers shift from using familiar gas vehicles to unfamiliar electric vehicles (EV). This study evaluated the functionality of the charging system for 657 EVSE (electric vehicle service equipment) CCS connectors (combined charging system) on all 181 open, public DCFC (direct current fast chargers) charging stations in the Greater Bay Area. An EVSE was evaluated as functional if it charged an EV for 2 minutes or was charging an EV at the time the station was evaluated. Overall, 72.5% of the 657 EVSEs were functional. The cable was too short to reach the EV inlet for 4.9% of the EVSEs. Causes of 22.7% of EVSEs that were non-functioning were unresponsive or unavailable screens, payment system failures, charge initiation failures, network failures, or broken connectors. A random evaluation of 10% of the EVSEs, approximately 8 days after the first evaluation, demonstrated no overall change in functionality. This level of functionality appears to conflict with the 95 to 98% uptime reported by the EV service providers (EVSPs) who operate the EV charging stations. The findings suggest a need for shared, precise definitions of and calculations for reliability, uptime, downtime, and excluded time, as applied to open public DCFCs, with verification by third-party evaluation.

Keywords: electric vehicle charging infrastructure, performance, renewable energy, zero emission vehicles

Suggested Citation

Rempel, David and Cullen, Carleen and Bryan, Mary Matteson and Cezar, Gustavo Vianna, Reliability of Open Public Electric Vehicle Direct Current Fast Chargers. Available at SSRN: or