Rainflow counting
The fatigue-analysis method borrowed to count battery cycles correctly.
Rainflow counting is an algorithm — originally from metal-fatigue analysis — that decomposes an irregular SoC time series into a set of discrete charge/discharge cycles with defined depths. It is the rigorous way to turn real, messy BESS operation into the weighted cycle counts that drive equivalent full cycles and degradation models.
Definition
A battery’s SoC trace is full of nested partial swings. Rainflow counting extracts closed cycles and their amplitudes from that trace, so each partial cycle is attributed a depth. Those depth-weighted cycles feed both EFC accounting and depth-dependent degradation models.
Typical range
Not a value but a method. The output is a histogram of cycles by depth, which is then weighted (deeper cycles age the pack more) into EFC and degradation estimates.
Why it matters
Naively counting cycles (e.g. one per day) badly misrepresents an asset that does many shallow swings or several deep ones. Rainflow counting is what makes EFC, warranty throughput tracking, and degradation attribution defensible rather than approximate.
How NuraVolt tracks it
NuraVolt applies rainflow counting to the SoC series to build a depth-resolved cycle histogram, which then feeds equivalent-full-cycle accounting and the capacity-fade model — so degradation is attributed to the actual cycling pattern, not a daily average.
Frequently asked questions
See also
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