Customer Perceived System Reliability and its Application in EV Charge Station

Certain systems are designed for providing services or utilities to customers. Such services or utility need to be sufficient to satisfy customers. The ultimate performance measure of these systems is customer satisfaction. For simplicity purpose, the term of utility will be used in the rest of the paper but it could mean service. Customers care about not only the availability of the utility but also the quantity of the utility. EV charge station is a good example. It provides charging power to the vehicles. When the customers come to the site, they want the charge port ready for them and can charge the vehicle reliably during the session per their expectation. They can be unhappy not only if the charge port is down but if the charging time takes too long than the rated. In this paper, inherent reliability is defined as the system's ability to provide utility to customers without considering customer perspective. Customer perceived reliability is the reliability that customers truly feel. The inherent system reliability may not necessarily be fully reflected in the customer perceived reliability. Detailed explanations are provided in Section 1. Defining and utilizing customer perceived reliability provides important aspect in understanding and improving system performance for customer satisfaction. In the rest of paper, several aspects of customer perceived reliability are discussed. The customer perceived reliability and availability for multi state system is defined and studied. The customer perceived reliability based component reliability importance is proposed. The results are applied to a simplified EV charge station, and the customer perceived availability is calculated and discussed. The potential applications is summarized in the last section.