SOH
SOH (state of health) shows how much capacity a battery has left compared with when it was new. An SOH of 92 % means 8 % has been lost to ageing.
What does SOH mean?
State of Health describes the battery’s condition: the ratio of today’s available capacity to the capacity when new. An SOH of 92 % after five years means the system has lost 8 % of its original capacity to ageing.
The SOH is the measured quantity behind warranty promises (“70 % after 10,000 cycles”) and the basis of any residual-value assessment — it makes degradation visible and comparable.
What matters in practice
- SOH must be readable via BMS/EMS — otherwise the warranty is unverifiable
- the trend curve matters more than a single value: kinks indicate problems
- warranty terms define how SOH is measured — read them closely
- design for end of life: capacity at warranty SOH
Practical example
An operator reviews the SOH trend annually. After three years one string shows 4 % more loss than the others — the service partner replaces a module under warranty before the string dominates system behaviour.
The Speichercampus perspective
Speichercampus designs projects around end-of-warranty capacity, not the as-new value — and selects systems whose SOH is transparently readable.