Battery degradation research highlights cell inconsistency and manufacturer variance

Research indicates that inconsistencies between individual battery cells can significantly reduce the lifespan of electric vehicle (EV) battery packs. A study published in ‘Nature Energy’ analyzed real-world data from 116 passenger cars and 17 electric buses. The findings show that cell-to-cell variation can shorten battery life by an average of 17.7 percent in passenger cars and up to 22.8 percent in electric buses. This degradation often becomes apparent only after high mileage, such as 170,000 kilometers, when the weakest cell limits the entire system's performance and capacity.

In a separate analysis, the ADAC, in collaboration with Aviloo, evaluated approximately 28,500 measurements regarding the State of Health (SoH) of plug-in hybrid electric vehicles (PHEVs). The study found that while most batteries are robust enough to last the typical lifespan of a vehicle, degradation rates vary significantly depending on the manufacturer and usage patterns. Frequent use of electric-only mode increases the number of charge cycles, thereby accelerating wear. Among the manufacturers studied, Mercedes-Benz demonstrated the slowest battery aging, while Mitsubishi showed notable weakness in long-term stability.