State of health

Example

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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.

Learn it in Lesson 2 · Capacity and C-rate →

Connected concepts

Related concepts from the knowledge graph. Connections show context, not cause and effect. Hover or focus a linked term for its definition.

Capacity fade

The loss of charge a cell can store and deliver, for example through lithium locked into the SEI or active material that has cracked out of service.

End of life

The point at which a cell no longer meets its application’s requirement, conventionally 80 % of initial capacity or a doubling of resistance. It is a definition for warranties and tests, not a point where the cell stops working.

Impedance rise

An increase in a cell’s internal resistance as it ages. It costs voltage under load and therefore power, even while the stored charge is still there.

Remaining useful life

A prediction of how many cycles, or how much time, a battery has left before reaching end of life. It is estimated from the trend of state of health, and is uncertain near a knee point where fade accelerates.

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.

State of charge

How full a cell is, as a fraction of its available capacity. State of charge, like temperature, affects how fast a stored cell ages.

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.

1. 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.

2. 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.