Beginning of Life (BoL) refers to the initial condition and performance characteristics of a battery at the time it is first commissioned for use—typically right after manufacturing, testing, and quality inspection, but before any significant operation, cycling, or aging has occurred. It represents the battery’s baseline state against which all future performance, degradation, and aging are measured.
Why BoL Matters:
Reference point for lifecycle analysis: Degradation (e.g. capacity fade) is tracked from BoL to End of Life (EoL)
Performance benchmarking: BoL values are used to verify whether the battery meets design specs
Warranty and service planning: Many warranties are based on maintaining a % of BoL performance
Model calibration: Battery models use BoL data for initial parameter settings (in simulations or BMS algorithms)
