Method for detecting critical condition in lithium-ion-battery of electric car, involves observing time course of internal resistance of cell, and determining whether critical condition is present in cell or battery based on time course

摘要

The method involves repeatedly determining internal resistance of a battery cell from voltage lying at the cell and current flowing through the cell, and observing a time course of the determined resistance of the cell. The resistance of the cell is derived from series circuit of ohmic resistors (11, 13, 15) and capacitors (12, 14). A determination is made to find whether critical condition is present in the cell or battery based on the course of the determined resistance. The battery is transferred to a safe condition when the critical condition is present in the cell. An independent claim is also included for a battery management unit.