초록 ▼

A state of charge indicator of a lithium ion battery computes a state of charge (SOC) corresponding to a cell open circuit voltage from a SOC-cell open circuit voltage characteristic map, and displays the SOC on a display device. Herein, the SOC-cell open circuit voltage characteristics are obtained

A state of charge indicator of a lithium ion battery computes a state of charge (SOC) corresponding to a cell open circuit voltage from a SOC-cell open circuit voltage characteristic map, and displays the SOC on a display device. Herein, the SOC-cell open circuit voltage characteristics are obtained by defining the battery charge amount when the open circuit voltage of the cell is 3.9 V as SOC=100%, and defining the battery charge amount when the open circuit voltage of the cell is 3.5 V as SOC=100%. By defining SOC=100% and SOC=0% in this way, the SOC can be correctly computed and displayed even if the battery has deteriorated.

대표청구항 ▼

[ What is claimed is:] [1.] A state of charge indicator for a battery comprising plural cells connected in series, the indicator comprising:a display device;a sensor which detects an open circuit voltage of the battery;a sensor which detects a charging/discharging current of the battery; anda microp

[ What is claimed is:] [1.] A state of charge indicator for a battery comprising plural cells connected in series, the indicator comprising:a display device;a sensor which detects an open circuit voltage of the battery;a sensor which detects a charging/discharging current of the battery; anda microprocessor programmed to:compute an open circuit voltage of a cell based on the detected battery open circuit voltage;compute an SOC (state of charge) corresponding to the computed cell open circuit voltage from an SOC-cell open circuit voltage characteristic map obtained by defining the battery charge amount when the open circuit voltage of the cell is a first predetermined voltage as SOC 100%, and defining the battery charge amount when the open circuit voltage of the cell is a second predetermined voltage as SOC 0%, wherein the open circuit voltage of the cell is in a range between the second predetermined voltage and the first predetermined voltage, the second predetermined voltage being set to be lower than the first predetermined voltage;compute the SOC by integrating the detected charging/discharging current when the open circuit voltage of the cell is greater than the first predetermined voltage; and display the computed SOC in the display device.