Cycling degradation testing and analysis of a LiFePO4 battery at actual conditions
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Date
2017-12-01
Authors
Panchal, Satyam
Mcgrory, Jake
Kong, J.
Fraser, Roydon
Fowler, Michael
Dincer, Ibrahim
Agelin-Chaab, Martin
Journal Title
Journal ISSN
Volume Title
Publisher
Wiley
Abstract
This paper presents a degradation testing of a lithium-ion battery developed using real world drive cycles obtained from an electric vehicle (EV). For this, a data logger was installed in the EV, and real world drive cycle data were collected. The EV battery system consists of 3 lithium-ion battery packs with a total of 20 battery modules in series. Each module contains 6 series by 49 parallel lithium-ion cells. The vehicle was driven in the province of Ontario, Canada, and several drive cycles were recorded over a 3-month period. However, only 4 drive cycles with statistical analysis are reported in this paper. The reported drive cycles consist of different modes: acceleration, constant speed, and deceleration in both highway and city driving at -6 degrees C, 2 degrees C, 10 degrees C, and 23 degrees C ambient temperatures with all accessories on. Additionally, individual cell characterization was conducted using a C/25 (0.8A) charge-discharge cycle and hybrid pulse power characterization (HPPC). The Thevenin battery model was constructed in MATLAB along with an empirical degradation model and validated in terms of voltage and SOC for all drive cycles reported. The presented model closely estimated the profiles observed in the experimental data. Data collected from the drive cycles showed that a 4.6% capacity fade occurred over the 3months of driving. The empirical degradation model was fitted to these data, and an extrapolation estimated that 20% capacity fade would occur after 900 daily drive cycles.
Description
This is the peer reviewed version of the following article: Panchal, S., Mcgrory, J., Kong, J., Fraser, R., Fowler, M., Dincer, I., & Agelin-Chaab, M. (2017). Cycling degradation testing and analysis of a LiFePO 4 battery at actual conditions. International Journal of Energy Research, 41(15), 2565–2575, which has been published in final form at https://doi.org/10.1002/er.3837. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
Keywords
battery degradation modeling, drive cycle, electric vehicle, lithium-ion battery, state of charge, voltage profile