Spherical tulip electrical contacts for quasi kinematic coupling of rapid swap batteries

Abstract

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 critical components for coupling the pack to the electric vehicle, yet state-of-the-art connections require precision alignment of contact surfaces and active retention mechanisms that may become stuck or fail to engage properly if the vehicle undergoes deformation, such as that experienced in rugged environments.

Here, we investigate the integration of electrical connectors with the battery mount’s structural loop to create a 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.

The result is 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 presented to accommodate angular misalignment and establish high contact area through elastic averaging. Contact resistance, a primary metric for evaluating the functionality of an electrical contact, is explored as a function of scrub, contact area, and compliance within the connector. Initial characterization of wear is also evaluated to identify failure mechanisms and to validate the design strategy of encouraging relative sliding motion at the contact interface to break through the continuously re-formed oxide layers on each mating cycle for improved conductivity.