A Fast OCV Characterization Approach for Battery Reuse Applications

Document Type

Conference Proceeding

Publication Date

1-1-2022

Publication Title

2022 IEEE Electrical Power and Energy Conference, EPEC 2022

First Page

194

Keywords

battery reuse, Fast Charge, Li-ion batteries, OCV-SOC Characterization

Last Page

199

Abstract

This paper considers the problem of open circuit voltage (OCV) to state of charge(SOC) characterization in rechargeable batteries for battery reuse applications. The traditional approach to OCV-SOC characterization is done by collecting voltage and current data through a slow discharge and charge process; this process usually takes about 60 hours. Such OCV-SOC characterization is performed on a few sample batteries because the OCV-SOC characterization is the same for new batteries coming out of the same manufacturing process. However, the characteristics of a battery may change as it is used for years in different environmental and usage conditions. Hence, they may need to be re-characterized before secondary use. Unlike primary characterization, secondary characterization may have to be done faster in order to save time and cost. This paper presents a new and faster approach for OCV-SOC characterization. The proposed approach in this paper consists of constant current profiles that halve in magnitude after a specified time. Such reducing current magnitude allows for fully depleting the battery; similarly, the battery is charged back with a reducing current profile in order to make sure the battery is fully charged back. The resulting current profile reduces the total characterization time by 1/5. It was hypothesized that the changing current magnitude may result in hysteresis voltage bias. For this, a new OCV modelling approach consisting of separate resistance estimation at each pulse was developed. The proposed approach was tested using data collected from four cylindrical Li-ion batteries. Compared to the traditional OCV modelling approach, the proposed approach results in 3% of SOC error and takes 20% of the time.

DOI

10.1109/EPEC56903.2022.10000173

ISBN

9781665463188

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