SOH (State of Health)
Definition
Estimate of battery degradation relative to new condition, typically expressed as percentage of original capacity or power capability remaining.
Why It Matters
- Indicates when battery replacement is needed
- Predicts remaining useful life for maintenance planning
- Affects warranty claims and lifecycle cost
- Helps optimize charging strategies to extend life
Common Pitfalls
- Not tracking capacity fade over multiple cycles
- Ignoring power fade (impedance increase) as separate metric
- Not accounting for calendar aging vs. cycle aging
- Assuming linear degradation (often non-linear)