Battery system

Abstract

A main object of the present disclosure is to provide a battery system capable of avoiding an over charge with a simple sensor element. The present disclosure achieves the object by providing a battery system comprising: a battery module including a battery pack A including a plurality of battery cells connected in series, and a battery pack B including a plurality of battery cells connected in series, connected in parallel, a monitoring unit configured to monitor a condition of the battery module, and a control unit configured to control at least a charge of the battery module, and the monitoring unit includes: a first current sensor configured to measure a total current IA of the battery pack A, and a second current sensor configured to measure a total current IB of the battery pack B, and the control unit includes: a calculating section configured to calculate a determining value based on the total current IA and the total current IB, and a determining section configured to determine an occurrence of an over charge based on the determining value.

What is claimed is: 
     
         1 . A method for determining an occurrence of an over charge for a battery module, wherein the battery module includes a battery pack A including a plurality of battery cells connected in series, and a battery pack B including a plurality of battery cells connected in series, and the battery pack A and the battery pack B are connected in parallel,
 the method comprising:   measuring a total current I A  of the battery pack A,   measuring a total current I B  of the battery pack B,   calculating a determining value based on the total current I A  and the total current I B , and   determining the occurrence of the over charge based on the determining value,   wherein a slope of a current ratio of the total current I A  and the total current I B  is calculated as the determining value, and   the occurrence of the over charge is determined from a condition, wherein the slope of the current ratio is a threshold or more, is maintained for a predetermined time.