Where I can evaluate the internal resistance of a battery pack which is developed in Battery Builder App in Simscape.

I designed battery pack in Battery builder app with parallel and series combination for A123cells from Matlab library. The total pack include 20 cells is parallel and 244 cells in series. Finally making a 805V, 392 Ah, 315 kW Li-ion battery pack. Where I can evaluate the internal resistance of a battery pack which is developed in Battery Builder App in Simscape.

I can see the cell details when I open the module too. Please support me to get the actual final internal resistance of battery pack which i have designed as per my desire with the inbuild simulink/simscape cell models. I have attached the details available on the module related to resistance. Kindly give your valuable commetns on this.

Answer 1

[MULI]

Hi @Designer,

Method 1:Table-Based Approach

Since you are using the Battery Builder app in Simscape, each cell includes a lookup table R₀(SOC, T) for internal resistance based on state of charge and temperature.

You can estimate the total pack resistance using:

Where Ns and Np are the number of series and parallel cells, and Rcell is selected from the resistance table at your desired operating conditions.

Method 2: Discharge Test

You can measure the open-circuit voltage V1, then apply a constant DC discharge current Idc using a "Controlled Current Source" block. While current is flowing, measure the terminal voltage V2, and compute:

This method captures practical effects like contact resistance and cell imbalance. You can use it when validating your model against real-world data or hardware tests.

You can refer to this MathWorks documentation for more information on "Controlled Current Source" block:https://www.mathworks.com/help/releases/R2024a/simscape/ref/controlledcurrentsource.html