Patent ID: 8742763

Claim:
A battery module state detection method applied to a battery module state detection device ( 1 ) for a battery module, the battery module comprising one or more lithium iron phosphate battery unit of an initial internal resistance value and being connected to a load, the battery module state detection device ( 1 ) comprising: a detecting unit ( 11 ), comprising a plurality of test terminals connecting respectively a positive electrode and a negative electrode of the battery unit for measuring an on-load voltage value and a no-load voltage value of the battery unit, a shunt ( 12 ), and a control unit ( 10 ) for obtaining an internal resistance value of the battery, the battery module state detection method comprising the following steps of: (a) measuring an on-load voltage value of the battery unit and a load current value of the load; (b) calculating an instant internal resistance value of the battery unit by first subtracting the on-load voltage value from the no-load voltage value, and then dived by the load current; (c) obtaining an operating state of the battery unit according to the instant internal resistance value and a relationship between internal resistance and discharging time; (d) obtaining a numerical value of a quality reference by dividing the instant internal resistance value with the initial internal resistance value of the battery unit, with the numerical value of the quality reference value initialized to 1 when the battery unit is just about to discharge for the first time; (e) defining a safe remaining energy value of the battery module as the lowest of the numerical value of the quality reference obtained for the one or more battery unit; and activating a protection mechanism for the quality reference value exceeding a preset threshold value greater than 1.