Lab Setup and Testing of Lithium-Ion Batteries with Focus on Dynamic and Aging Modeling

Abstract

This report presents the work on making a lab setup for testing of different types of batteries in the energy storage lab at NTNU/SINTEF. A complete lab setup has been made and two different LiFePO4 chemistry cells of size 10Ah and 130Ah have been tested in the lab confirming the usability of the setup for battery testing. The lab setup mainly consists of two DC-DC converters, a PC with LabVIEW software to control the converters and external measurements via a NI cDAQ-unit. A LabVIEW program was developed to allow automatic cycling of batteries after a reference file which allows different types of battery tests.In addition to making the lab setup battery modeling is reviewed including the battery aging model developed in the semester project. The batteries acquired for validating the setup were tested. The testing has included discharge tests of both cells and a dynamic battery model have been fitted to the results from the 130Ah discharge test. The fitted model shows good simulation results. Additional discharge tests can be done to make a more complete model of the battery, especially the cycling at low SOC and different currents should be emphasized. An aging test of the two 10Ah cells were initiated where the two cells were cycled in two different profiles consisting of one cycle of ∆DOD=0.7 and three cycles at ∆DOD=0.2. No degradation was found after 288 cycles performed at this profile. Comparing this profile with the battery aging model showed that not more than a 1% reduction of capacity was to expect. Additional cycling should be performed to spot the degradation of the cells.