BESS Ageing vs Duty Cycle

A look at this paper and how it compares to what we see in the field.

Xu J, Li H, Hua S and Wang H (2025) Experimental investigation of grid storage modes effect on aging of LiFePO4 battery modules. Front. Energy Res. 13:1528691.

Introduction: To investigate the degradation behavior of energy storage batteries during grid services, we conducted a cyclic aging test on LiFePO4 battery modules.

Methods: Incorporating variables such as grid duty, temperature and depth of discharge, we analyzed the capacity degradation and operational patterns in different grid- storage interaction modes by examining aspects of capacity retention, discharge quantity, incremental capacity, and differential voltage.

Results: Our findings indicate that battery degradation is higher during peak shaving compared to frequency regulation. Heat and deep charging and discharging modes accelerates battery aging.

Discussion: The primary source of performance degradation in LiFePO4 batteries is Li loss.

We see this in the field constantly. Same capacity, wildly different degradation across assets running different grid services. Now there’s a clean paper that confirms it.

A team from a battery test equipment manufacturer ran 16 months of cycling tests on 220Ah LFP modules using actual peak shaving and frequency regulation profiles from a storage power station.

Peak shaving degrades 1.8x faster than frequency regulation. Same SOC range, same temperature. Shallow SOC windows (30–80%) age 1.65x slower than deep cycling.

Most fleet operators still model degradation as a function of cycle count, not service mix. If you’re stacking revenue without modeling what each service does to your asset, you’re optimizing income and ignoring cost.