Battery knowledge · State estimation

Differential voltage analysis

Plotting the derivative of voltage with respect to charge during a slow cycle. Its peaks mark electrode phase transitions, and how they shift between cycles separates lithium inventory loss from active-material loss without opening the cell.

Abbreviation
DVA
Also called
dV/dQ
Relationship
dV/dQ vs Q

Example

Interpret a local slope

If voltage changes by 0.020 V over 0.10 Ah in a slowly measured region, the local slope is approximately 0.20 V/Ah. Comparing curves requires consistent current, temperature, sampling and preprocessing.

Explore the graph

Differentiate an authored monotonic voltage curve to see the information in DVA and ICA.

Authored voltage curve
Authored voltage curveNormalized charge q = Q/Q_nominal versus Voltage (V). Voltage. Interpretation follows the graphs.303.250.253.50.53.750.7541Normalized charge q =Q/Q_nominalVoltage (V)
Voltage
Differential voltage
Differential voltageNormalized charge q versus dV/dq (V per charge fraction). DVA. Interpretation follows the graphs.000.2750.250.550.50.8250.751.11Normalized charge qdV/dq (V per chargefraction)
DVA
Incremental capacity
Incremental capacityVoltage (V) versus dq/dV (charge fraction/V). ICA. Interpretation follows the graphs.0313.2523.533.7544Voltage (V)dq/dV (charge fraction/V)
ICA

At the plateau center, dV/dq = 0.44 V per charge fraction; dq/dV = 2.273 charge fraction/V.

DVA = dV/dq; ICA = dq/dV = 1 / (dV/dq), q = Q/Q_nominal

Illustrative model. Normalized authored curve, not a measured cell fingerprint. Peak changes alone do not uniquely identify a degradation mechanism.

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.

  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.