This example shows how to model a lead-acid battery cell using the Simscape™ language to implement the nonlinear equations of the equivalent circuit components. In this way, as opposed to modeling entirely in Simulink®, the connection between model components and the defining physical equations is more easily understood. For the defining equations and their validation, see Jackey, R. "A Simple, Effective Lead-Acid Battery Modeling Process for Electrical System Component Selection", SAE World Congress & Exhibition, April 2007, ref. 2007-01-0778.
In this simulation, initially the battery is discharged at a constant current of 10A. The battery is then recharged at a constant 10A back to the initial state of charge. A simple thermal model is used to model battery temperature. It is assumed that cooling is primarily via convection, and that heating is primarily from battery internal resistance, R2. A standard 12 V lead-acid battery can be modeled by connecting six copies of the 2V battery cell block in series.
This model is constructed using the Simscape example library LeadAcidBattery_lib. The library comes built and on your path so that it is readily executable. However, it is recommended that you copy the source files to a new directory, for which you have write permission, and add that directory to your MATLAB® path. This will allow you to make changes and rebuild the library for yourself. The source files for the example library are in the following package directory: matlabroot/toolbox/physmod/simscape/simscapedemos/+LeadAcidBattery where matlabroot is the MATLAB root directory on your machine, as returned by entering matlabroot in the MATLAB Command Window.