Explore the contents of this article with a free Wolfram SystemModeler trial. How do different activities such as making phone calls, watching video, listening to music, or browsing the web affect cell phone battery life? What about the temperature—does it matter if the cell phone is in a warm pocket or out in the cold? In this blog post, we'll investigate how a model constructed with Wolfram SystemModeler can help in finding answers to such questions. An area where battery usage is taking off right now is cell phones. There are different kinds of battery types used in cell phones: nickel metal hydride, lithium-polymer, and Li-ion. The superior energy density, power density, low self-discharge, and long cycle life of the Li-ion batteries makes them interesting for cell phone applications. In this blog post, we'll look at Li-ion cells of the type LiFePO4, where lithium ions move from the negative electrode to the positive electrode during discharge and the other way around when charging. The are many types of battery models: analytical, electrical circuits, electrochemical, and combinations of these types. Our model of choice is the electrical circuit model, which provides sufficient accuracy for top-level performance analysis and is easy to connect to other systems. A typical schematic for an electrical circuit model of a battery cell might look something like this:

Explore the contents of this article with a free Wolfram SystemModeler trial. Refrigerators and freezers are common household appliances, present in almost every home. That means most people use one every day, but how do they actually work? And what happens to the temperature when you open the door? Or when the power goes out during a storm? Those are some of the questions this blog post seeks to answer by building a refrigerator model in Wolfram SystemModeler. A common way to construct a combined refrigerator and freezer is to keep the freezer compartment cool with a heat pump and to then transfer some of the air to the fridge compartment. That way only one heat pump is needed, and both compartments can be kept at different temperatures. The following diagram shows our goal: modeling a connected freezer and fridge complete with doors, casing, food contents, and a heat pump. At the top we see the freezer compartment together with the heat pump that cools the air, some frozen food in the freezer, and a door for the freezer. At the bottom we see a similar structure for the fridge. The two are connected with a component for air circulation at the middle right of the diagram, which will transfer cold air from the freezer to the fridge. Finally, to the left, we have components modeling the casing and insulation to the room temperature outside.