Battery Specific Heat
Penn Electric Racing
The goal of this experiment is to calculate the actual specific heat of the battery pouch cells. To the right, you can see a graph of the temperature inside the accumulator (battery back) as compared to expected temperature by specific heat (from Vehicle Dynamics simulations). If the temperature of the accumulator gets above 60 degrees, the car will shut off to prevent thermal runaway.
To improve the VD simulation, and help characterize how much cooling the car might require, my team researched and then devised a calorimeter experiment. To the left, you can see a block of aluminum (with known specific heat) that was machined to the same weight as the cells. By submerging a cell at a certain temperature adiabatically in water at a certain temperature and them measuring the equilibrium temperature, the specific heat can be determined if mass of both the water and the cell is known. The aluminum is included to calibrate the experiment.
The calculation uses the specific heat equation as seen below.
Cell and water temperatures as measured by the type T thermocouples during testing
Experimental setup for obtaining mass of water with the thermocouple attached to the styrofoam to measure water temperature.