May 2017 - Despite recent developments surrounding fast electric vehicle charging and an ever-growing interest in research, little is known about how people actually use direct current fast chargers (DCFC) or how different pricing may affect their recharging behavior. Understanding consumer behavior in DCFC usage is critical to successful deployment of DCFC and economical pricing of the service usage. This paper analyzes real-world field data to examine DCFC usage in the United States. In particular, it examines changes in recharging behavior between periods when the charging service was free and when it was not. Results from this study show evidence that a flat-rate fee has a negative effect on the usage efficiency of DCFC stations.