In this article we examine four typical technical challenges BESS assets face at the beginning of their lifecycle and how battery analytics can help to overcome them. All are based on real-life BESS projects with sizes between 20MW and 200MWh. Insights are anonymised and modified to respect the confidentiality of ACCURE’s customers.
1. Battery cell quality
Battery cells are the heart of a BESS; their quality makes or breaks a system’s ability to provide value. But high battery quality is not a given. Even the best cell manufacturing lines have significant scrap rates and produce batteries of varying qualities. New cell chemistries, exponential growth, accelerating product development cycles, and the advent of new suppliers hyper-scaling into the market have not improved this situation.
Today, the industry typically uses end-of-line (EOL) testing and sorting at the factory to ensure a minimum cell quality and to deal with the inevitable spread in cell properties during battery production. One typical test is to use an AC power source providing a current pulse at 1,000 Hz to measure the internal resistance of the cells.
Cells with similar properties are grouped, and outliers go straight to recycling. Internal resistance is not typically evaluated during commissioning and operation, but it should be. Today, internal resistance can be tracked by combining battery management system (BMS) readings and advanced cloud computing capabilities.
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