Model assumptions and limitations

The Thevenin Battery Model represents a battery with a simple equivalent circuit. It is useful for many applications, but it is still an approximation.

Assumptions

• Battery behavior can be captured by an equivalent circuit.
• OCV depends mainly on State of Charge.
• Losses are represented by resistive and capacitive elements.
• Parameters are assumed constant for a given condition.
• One or more RC networks approximate the dynamic response.

Limitations

• Parameters change with SoC, temperature, age, and operating conditions.
• The model does not capture electrochemical reactions directly.
• Aging and degradation require extra modelling.
• Accuracy depends on parameter identification.

Characterization

The Thevenin parameters must be found experimentally for each battery. Characterization tests provide OCV, ohmic resistance, polarization resistance, and capacitance values.

The next chapter describes the experimental process for parameter identification.