Nearly 10,000 Used EV Cell-Level Tests Reveal Voltage Imbalance Issues
UK battery diagnostics company Generational released findings in late August 2026 from cell-level tests conducted on approximately 10,000 used electric vehicles across the UK. The data showed a median voltage difference of 8 millivolts between the highest and lowest cells in the tested sample. However, one in every 85 vehicles exhibited a voltage imbalance exceeding 50 millivolts, while one in 200 vehicles showed an imbalance surpassing 100 millivolts. Generational stated that imbalances above 50 millivolts require further investigation, and those exceeding 100 millivolts may indicate a potential underlying fault.
Oliver Phillpott, CEO of Generational, noted that the industry commonly relies on State of Health (SoH) metrics to assess used EV battery conditions. However, SoH only reflects overall battery capacity and cannot reveal potential issues at the cell level. He emphasized that a single faulty cell can limit the performance of the entire battery pack, causing the Battery Management System (BMS) to restrict charging or discharging. This, in turn, may affect vehicle range, the accuracy of state-of-charge estimates, and charging behavior. Such problems often remain undetectable until the imbalance becomes severe.
Cell-Level Testing Emerges as a New Trend
Generational incorporated cell voltage testing into dealer diagnostic processes starting in April 2026. In July 2026, the company partnered with UK automotive repair diagnostics firm Maverick Diagnostics to distribute OBD-port test kits to approximately 6,000 repair shops across the country. Generational explained that EV batteries consist of hundreds of cells connected in series, with the overall charging and discharging performance limited by the first cell to reach full charge or complete discharge. When a single cell malfunctions, the entire battery's performance is compromised, yet traditional average voltage tests often fail to detect such issues in a timely manner.