Cycle Life
Definition
Number of charge-discharge cycles a battery can complete before capacity degrades to a specified percentage (typically 80%) of original capacity.
Why It Matters
- Primary metric for predicting battery replacement timing
- Depends heavily on depth-of-discharge and C-rate
- Modern lithium-ion cells: 1000-3000 cycles at 80% DOD
- Calendar aging also contributes to total lifetime
Common Pitfalls
- Not specifying DOD and C-rate when quoting cycle life
- Ignoring temperature effects on cycle life
- Assuming linear degradation (often non-linear)
- Not accounting for calendar aging in lifetime prediction