With the recent increase of Li-ion batteries in the transport sector, the re-use of the electric vehicles' batteries in stationary applications for grid services is growing interest. Such batteries are called “second life” batteries and generally present 70-80% of the new battery nominal capacity, showing a very high variability of remaining useful capacity. This, considering multiple units are integrated in a stationary battery system which, moreover, requires a continuous operation to guarantee grid services, causes issues in assessing batteries actual state-of-charge (SoC). To this aim, a novel methodology is proposed, hybridizing coulombic counting and open circuit voltage (OCV) direct methods, to overcome the limits of both methods. Specifically, a good SoC estimation during flat voltage charge and discharge is allowed by the coulombic counting, while the OCV direct method enables to reinitialize the SOC assessment when failures or malfunctions of the data acquisition system occur. The proposed method is verified applying it for the SoC assessment of a real second life battery installation for grid support services in an off-grid application.

State of Charge Real-Time Evaluation of Second-Life Batteries for Islanded Grid Support

Dario Pelosi;Linda Barelli
2024

Abstract

With the recent increase of Li-ion batteries in the transport sector, the re-use of the electric vehicles' batteries in stationary applications for grid services is growing interest. Such batteries are called “second life” batteries and generally present 70-80% of the new battery nominal capacity, showing a very high variability of remaining useful capacity. This, considering multiple units are integrated in a stationary battery system which, moreover, requires a continuous operation to guarantee grid services, causes issues in assessing batteries actual state-of-charge (SoC). To this aim, a novel methodology is proposed, hybridizing coulombic counting and open circuit voltage (OCV) direct methods, to overcome the limits of both methods. Specifically, a good SoC estimation during flat voltage charge and discharge is allowed by the coulombic counting, while the OCV direct method enables to reinitialize the SOC assessment when failures or malfunctions of the data acquisition system occur. The proposed method is verified applying it for the SoC assessment of a real second life battery installation for grid support services in an off-grid application.
2024
9788887237627
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11391/1593156
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