Batch diagnosis of batteries within one second

<h2>Summary</h2> As demand grows for scalable and sustainable energy storage, fast and affordable diagnostics are urgently needed, especially for factory-level cell sorting and second-life assessments. Electrochemical impedance spectroscopy (EIS) is widely used but remains too slow, complex, and costly for large-scale use. This work introduces a multi-channel and multi-frequency electrical excitation response (MMER) technique that captures comparable impedance-related information at a fraction of the time and cost. MMER can diagnose entire battery modules in 1 s, regardless of cell count. It uses a binary multi-frequency excitation signal, implemented on simple hardware such as programmable logic devices. Unlike EIS, MMER avoids frequency-domain transformation and impedance fitting. Instead, it compares raw voltage responses under a shared excitation current to reveal performance variations. Experiments show MMER tracks cell health in line with EIS while reducing test time by over 99%. It supports real-time diagnostics even during high-rate cycling and extends to other electrochemical systems.