| CPC H01M 10/482 (2013.01) [G01R 31/3835 (2019.01); G01R 31/3842 (2019.01); H01M 10/486 (2013.01); H02J 7/0025 (2020.01); H01M 2220/20 (2013.01)] | 4 Claims | 

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               1. A process of using a battery system, the battery system comprising: 
            a battery pack including a plurality of battery cells connected in series, 
                a monitoring unit configured to monitor a condition of the battery pack, and 
                a control unit configured to control at least a discharge of the battery pack, and 
                the monitoring unit includes: 
                a voltage sensor configured to measure a total voltage of the battery pack, 
                a current sensor configured to measure a total current of the battery pack, and 
                a temperature sensor configured to measure a temperature of the battery pack, 
                the process comprising the control unit: 
                calculating capacity condition A of the battery pack at a first discharge cutoff voltage based on the total voltage and the total current, 
                estimating capacity condition B of the battery pack at the first discharge cutoff voltage based on the total current and the temperature, 
                determining an occurrence of an over discharge based on the capacity condition A and the capacity condition B, and 
                changing the first discharge cutoff voltage to a second discharge cutoff voltage that is higher than the first discharge cutoff voltage, when the occurrence of the over discharge is determined. 
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