Reliability of Bolted Aluminum Busbars for Battery Systems: Effect of Nickel Coating and Corrosive Environment

Bolted busbar connections are a simple and versatile connection method used in battery systems. Copper busbars are widely used for such bolted connections; however, aluminum offers the potential to save weight and cost. To date, the reliability of aluminum connections dimensioned for battery systems and the vulnerability to corrosion accelerants is not established. In this study, bolted aluminum connections were tested under operational and environmental conditions applicable to battery systems. Four bolted configurations (AA1070 and AA6101, with nickel plating or brushed contact surfaces) were exposed to corrosive environments and current-induced thermal cycling. Nickel plating provided a robust contact interface that maintained stable resistance over 6000 cycles across three temperature levels. The nickel plating’s electrical performance was unaffected by the corrosive environments, including humidity, salt mist, and hydrogen sulfide exposure. The brushed aluminum configurations produced connections with greater contact resistance variation and achieving a joint performance factor < 1.5 was critical for long-term reliability. The growing appeal of aluminum in battery systems requires verification methods capable of assessing new contact configurations. Currently, corrosion test environments for evaluating aluminum contacts are lacking in the literature. This study provides insights into the performance of bolted aluminum configurations dimensioned for battery systems and provides methodology for accelerated verification of new configurations.

I. Introduction

Aluminum is an attractive conductor for use in battery systems offering the potential to save cost and weight in comparison to copper conductors. However, maintaining reliable electrical connections with aluminum entails additional challenges compared to copper [1]. Extensive research has been conducted into aluminum’s failure mechanisms establishing recommendations for aluminum connections [2]. Also, industrial experience has led to the formation of standards [3]–[5] for their evaluation. That being said, research and industrial experience on aluminum have predominately focused on high-voltage power transmission and building cables, with limited testing conducted on the reliability of aluminum connections in low-voltage high-current dc applications.