Abstract:The shift from conventional internal combustion engine vehicles to electric vehicles (EVs) hinges on both the quantity and quality of EV charging infrastructure. While much research has focused on the importance of and challenges to increasing the quantity of EV chargers worldwide, less has been devoted to assessing the quality of existing EV chargers. Here, we analyze a year’s worth of real-world EV charging data from 132 EVs driven in California, to provide insights about the reliability of EV chargers as experienced by EV drivers. By quantifying and qualifying the level of disruption associated with both real and hypothetical charge failures, we nd that EV chargers are not all equally important to EV drivers, highlighting the need for more nuanced charging reliability standards to effectively meet consumer charging needs. While the level of disruption associated with a charge failure for over 90% of charging sessions was fairly low, the consequences of a charge failure for the remaining sessions were catastrophic - 3% of hypothetical charge failures and 0.3% of the real charge failures led to drivers being stranded. These highly disruptive charge failures are associated with long distance travel (LDT), low charger density areas, DC Fast charging, and lack of access to home charging – chargers linked to these conditions should ideally be held to much higher standards than chargers linked to lower levels of disruption.