Depth of discharge (DoD)
How deep each cycle goes — and what it costs in lifetime.
Depth of discharge (DoD) is the fraction of a battery’s capacity removed in a discharge, the inverse of the SoC left behind. Warranties are usually quoted at a reference DoD (often 80%). Deeper, more frequent cycling accelerates degradation, so DoD is a core dispatch-versus-longevity lever.
Definition
DoD = 1 − SoC at the bottom of a discharge. An 80% DoD cycle runs from 100% to 20% SoC. Cycle-life ratings are always stated at a reference DoD, because shallower cycles are gentler and a battery delivers far more shallow cycles than deep ones.
Formula
DoD (%) = 100 − (SoC at end of discharge, %)
Typical range
Warranty reference DoD: commonly 80%. Many operators cap upper SoC at 90% in low-revenue hours to slow ageing. Contracted cycles/day: typically 1.5–2 for storage, higher for ancillary-services assets.
Why it matters
DoD is one of the few degradation drivers fully under operator control. Trading some depth for longevity — or capping upper SoC — can extend warranty life with minimal revenue impact. Exceeding the contracted DoD or cycles/day can also void warranty cover.
How NuraVolt tracks it
NuraVolt decomposes the dispatch profile into cycles and their depths (via rainflow counting), checks them against the contracted DoD and cycles/day limits, and quantifies the degradation cost of each dispatch decision.
Frequently asked questions
See also
A single number that normalises messy partial cycling into full-cycle equivalents.
The fatigue-analysis method borrowed to count battery cycles correctly.
How full the battery is — and why dwelling near full ages it.
The other major controllable degradation driver.
See this on your own plants
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