Tuesday, 07 June 2022 14:29

Study: Public Chargers Far Less Reliable than Previously Reported

Written by Mark Kane, InsideEVs


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The reliability of the public DC fast-charging stations is a crucial element of electrification and, according to a recent study, it's disappointing right now.

University of California Berkeley's David Rempel and Carleen Cullen, together with other researchers, tested a total of 657 individual CCS connectors (Combined Charging System 1/SAE J1772), available at 181 open, public charging stations in the Greater Bay Area.


As it turns out, only 72.5% of the units were functioning, meaning they worked for at least two minutes of testing; 22.7% were not functioning---meaning they had unresponsive or unavailable screens, payment system failures, charge initiation failures, network failures or broken connectors; and 4.9% had a design failure in the form of a cable that was too short.


It's an unacceptably low level, considering the fact DC fast chargers are critical infrastructure for transport, as well as at the current stage, the distance between charging stations often does not allow to skip a charger, and the general public needs convincing that BEVs are a practical and reliable solution.


The result is far lower than previously reported and, according to the study, it's not bad luck, as a random evaluation of 10% of the chargers, approximately eight days after the first evaluation, demonstrated no overall change in functionality results.


The paper noted the level of 72.5% is far below the 97% to 99% minimum uptime required by public funding agencies.


For the sake of the industry, the authors proposed to create a new standard to measure the reliability of charging infrastructure, which is a pretty good---and late---idea, considering billions will be spent on more chargers.


"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 study said. "The findings suggest a need for...

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