Why Constant Current Models Are Prominent

Modelling Batteries Under Constant Resistance

For your specific case of constant resistance, you'll need to adapt traditional models to account for the resistance-dependent nature of the load. Here’s a general approach to modelling batteries under constant resistance:

1. Understand Your Battery's Dynamics

• Electrochemical Model: Start with a detailed understanding of the electrochemical processes in your Zn-air battery. This includes the electrochemical reactions, mass transport phenomena, and potential side reactions.
• Battery Parameters: Determine key parameters such as open-circuit voltage (OCV), internal resistance, and capacity.

2. Adapt the Existing Models

• P2D Model Adjustments: The Pseudo-Two-Dimensional (P2D) model is commonly used for constant current conditions. You’ll need to adjust this model to incorporate variable load conditions.
• Load Resistance Integration: Integrate the load resistance into the model equations. The current will vary with the battery voltage and load resistance in a constant resistance scenario. Modify the current equations accordingly.
• Dynamic Resistance Model: If your resistance varies over time or with state of charge, incorporate a dynamic resistance model into your simulation. This will capture the real behaviour under variable loads.

3. Simulation and Analysis

• Numerical Methods: Use numerical methods to solve the differential equations of the adapted model. Software like MATLAB, COMSOL, or Python libraries can be useful here.
• Experimental Validation: Validate your model with experimental data from your constant resistance setup. This step is crucial to ensure that your theoretical model accurately represents real-world behaviour.

4. Resources and Literature

• Research Papers: Look for papers that discuss battery modelling under different loading conditions, including variable or non-constant loads. While constant resistance is less common, papers on dynamic loading might provide insights. Examples: Search for terms like "battery modelling variable load," "dynamic resistance battery modelling," or "non-constant current battery models."
• Textbooks: Books on battery modelling and electrochemical systems may provide foundational knowledge that can be adapted to constant resistance scenarios.
• Software and Tools: Use simulation tools that allow customization of load conditions. COMSOL Multiphysics, MATLAB Simulink, or Python with SciPy can be tailored to model various loading scenarios.

Practical Tips

• Consult with Experts: Reach out to researchers or practitioners who have experience with non-standard battery testing setups. They might have valuable insights or unpublished work related to your specific scenario.
• Community and Forums: Engage with academic forums or online communities focused on battery modelling. They can offer advice, share experiences, and guide modelling strategies.

By adapting existing models and utilizing the right tools and resources, you can effectively model your Zn-air battery under constant resistance.