Lemonergy · Studio block

Capacity health index

Endpoint-normalized health index with raw value and out-of-reference flag.

Implementation ID: battery-capacity-health
Reviewed: 2026-10-27

Behavior

Maps a measured capacity or resistance between user-selected fresh and end-of-life endpoints. It returns a clipped health index, the raw index and a flag for values outside the reference interval.

Interface

Original Lemonergy interface view. Lines identify ports; they are not a completed simulation circuit.

Ports and observed outputs
Name	Direction	Unit	Meaning
`measurement`	input	Ah	Measured capacity (Ah); scalar.
`health`	output	1 (fraction)	Clipped health index; scalar.
`raw`	output	1	Unclipped index; scalar.
`outside`	output	true / false	Outside reference range; scalar.

Parameters

Defaults are initial model values. Select values for your own model and operating conditions.

Configuration fields
Parameter	Unit	Default	Meaning and limits
New capacity (Ah) `fresh`	Ah	2	New capacity (Ah). This is an editable model input; the default belongs to the synthetic worked example.
End-of-life capacity (Ah) `end`	Ah	1.6	End-of-life capacity (Ah). This is an editable model input; the default belongs to the synthetic worked example.

Equations and rules

raw = (measurement - end) / (fresh - end)
health = clamp(raw, 0, 1)

Worked example

Capacity health index worked example

Use the defaults below with Measured capacity (Ah) = 1.8 Ah. At 0 s, Clipped health index is 0.5 1 (fraction). Additional checks are listed below.

Open Studio example after release →

Numerical checks for the bundled synthetic example
Output	Time (s)	Expected value	Unit	Absolute tolerance
Clipped health index `health`	0	`0.5`	1 (fraction)	1e-08

Explore the recorded outputs

Capacity health index recorded example

Capacity health index / Clipped health index

Capacity health index / Clipped health index: 0.5 1 (fraction) at 0 s

2 actual recorded samples. Lines are visual guides between samples. Synthetic example, not measured cell data.

Download the recorded samples (JSON) · Open this Studio example after release

Use in a workflow

Capacity health index worked example

Endpoint-normalized health index with raw value and out-of-reference flag.

Capacity health index: Maps a measured capacity or resistance between user-selected fresh and end-of-life endpoints. It returns a clipped health index, the raw index and a flag for values outside the reference interval.
- Use the parameter values in the block reference.
- Implementation tested locally; public release pending.

Open Studio example after release

Connected concepts

Limits and interpretation

This endpoint-normalized index is not the same quantity as capacity retention. The endpoint choice determines its interpretation.
The example verifies numerical behavior for synthetic parameters. Cell characterization and validation for an intended use are separate tasks.

Scientific and mathematical references

These sources explain the scientific and mathematical background. The behavior, interface and limits above define the Lemonergy implementation; a citation does not imply every model option in the source is implemented.

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
Technical reference · Model-based battery state-of-charge and parameter estimation with extended Kalman filtering, including uncertainty and model dependence.

Implementation sources

This reference follows the public interface and locally verified numerical checks for an upcoming release.

Contract: Lemonergy Studio public contract · Verification record: verification-2026-10-27

docs/glossary/native-block-verification.json

This implementation and its workflow uses (JSON) · Knowledge graph (JSON-LD)