Battery knowledge · State estimation
State of certified energy
A vehicle battery’s present usable energy, read from the on-board monitor, as a percentage of the usable energy certified when new. UN GTR 22 requires at least 80 % after 5 years or 100 000 km and 70 % after 8 years or 160 000 km; Euro 7 raises the second figure to 72 % for cars.
- Abbreviation
- SOCE
- Unit
- %
- Relationship
- SOCE = E_usable,now / E_usable,certified × 100 %
Example
Compare retained and certified usable energy
A battery delivering 54 kWh in the relevant assessment against a 60 kWh certified reference has SOCE = 90%. Keep the required assessment conditions and reference definition consistent.
Explore the graph
State of energy describes the energy currently available; certified-energy retention compares maximum usable energy with its original certified value.
Certified energy is 100 Wh; current maximum is 80 Wh, so SOCE is 80%. When half that current maximum is stored, SOE is 50% regardless of the SOCE value.
SOE = E_available / E_max,now; SOCE = E_max,now / E_certified
Illustrative model. Both ratios need stated reference conditions. Usable energy depends on temperature, load, voltage limits and the measurement method.
Use in Lemonergy
Distinguish internal states from noisy measurement estimates.
This is a reference concept. No executable Lemonergy block has been verified for this term.
References & further reading
Further reading on this topic
These sources provide broader context; they are not presented as citations for every statement in this entry.
- Extended Kalman filtering for battery management systems of LiPB-based HEV battery packs: Part 3. State and parameter estimation
Gregory L. Plett · Journal of Power Sources · 2004
Topic background · Model-based battery state-of-charge and parameter estimation with extended Kalman filtering, including uncertainty and model dependence.
- Extended Kalman filtering for battery management systems of LiPB-based HEV battery packs: Part 2. Modeling and identification
Gregory L. Plett · Journal of Power Sources · 2004
Topic background · Battery charge balance, open-circuit voltage, ohmic loss, polarization dynamics and model identification; parameters require cell-specific data.