State of health: The critical metric for measuring battery ageing and performance, and why it matters for BESS
AI-summarised brief · reviewed before publication
State of health (SoH) is a percentage measure of remaining charge capacity in battery cells compared with their original rating, and it is a core metric for operating and managing grid‑scale battery energy storage systems (BESS). SoH declines as cyclic and calendar ageing reduce capacity, raising internal resistance and limiting current delivery. The battery management system predicts degradation, linking SoH to state of charge (SoC) and safety risks such as thermal runaway. Operators monitor SoH to schedule cell replacements, avoid costly fires, and optimise operational expenditures. Factors that accelerate SoH loss include high charge‑discharge rates, elevated temperatures, deep cycles and inefficient BMS control. Understanding true SoH therefore enables longer‑lasting, safer, and more cost‑effective BESS deployments across diverse renewable integration projects.
💡 Why It Matters
- · Accurate SoH data lets operators intervene before a cell failure cascades into a plant‑wide outage, turning a maintenance cost into a predictable expense.