Development of Mechanical and Electrical Interfaces for Rapid Swap Battery Systems

Abstract

In the drive towards a globally decarbonized energy economy, rapid swap battery packs provide a potential means to improve electric vehicle adoption in high utilization industrial vehicles where lengthy charge times are a barrier to electrification. High voltage, high current battery connectors are a critical component for coupling the pack to the electric vehicle, distributing power from the battery to the drivetrain. Most state-of-the-art connections require precision alignment of contact surfaces, and bolted preload or retention mechanisms, hindering the implementation of rapid swap battery systems. The need for robust, high life cycle, high-power contacts motivates a new approach to connector design. The integration of electrical connectors with the battery mount’s structural loop creates a new design space where preload, geometry, and contact resistance may be optimized. This co-design approach enables mechanical and electrical functional requirements to be considered in conjunction to ensure reliable fulfillment in both areas while reducing the time for battery pack swaps. This work introduces two distinct approaches for aligning the pack to the vehicle, locking the battery in place, and engaging electrical contact with geometry unique to the system design. These approaches offer higher reliability, mechanical and electrical longevity, and automatic alignment capabilities during loading of the battery pack. Across both designs, the contact resistance is the primary metric for evaluating the electrical performance, and the contact pressure is used to evaluate the risk of mechanical wear. The first approach integrates a quasi-kinematic coupling-based connector with integrated electrical contacts, allowing for repeatable and accurate positioning of the battery pack to the vehicle. A slotted ball and socket design approach is considered to accommodate for angular misalignment and establish repeatable contact area through elastic averaging. The second approach proposes a planar contact to further reduce the contact pressure and increase contact longevity without the need for expensive and rare hardened coatings. This system relies on a rail and flat system for guiding the battery pack into a locked position and engaging the planar contacts.