Why did we change it?
The original State of Health (SoH) metric needed an improvement. It mixed imbalances with system degradation. This didn't represent true degradation, which led to confusing behaviour:
SoH values sometimes increased unexpectedly (e.g., after rebalancing)
Misalignment with how health is defined in warranty contracts
We needed something clearer, more stable, and aligned with real-world expectations.
What’s new with our SoH update?
SoH is a clean improvement from the past. It focuses on aging only and ignores other effects, which are not relevant for the SoH estimation.
As a reference, it uses by default the total installed energy, which is derived from a bottom up calculation based on the cell information.
Key Improvements
Only considers degradation (aging)
Ignores imbalances, weak cells, system rebalancing, and other transient effects
Aligns with warranty definitions and technical expectations
Where can I find the old SoH?
Since the "old" SoH included aging and other performance limiting effects, it is replaced with the existing Usable and Recoverable Energy. You can plot these KPIs using the TWAICE Warranty & Guarantee Tracker, for the entire system, but also for the individual strings.
The original SoH metric will no longer be shown by default. If you need historical values for comparison or reporting, please reach out to us.