Detecting whether a battery management system is abnormal

A battery management system, comprising a measure unit;

• a control unit coupled to said measure unit;
• a first monitoring resistor coupled to said measure unit;
• a second monitoring resistor coupled to said measure unit;
• a first capacitor coupled to said measure unit;
• a first switch coupled to said measure unit;
• and
• a first balance resistor coupled to said measure unit, wherein a first cell in a battery pack is coupled to said first monitoring resistor, said second monitoring resistor, said first capacitor, said first switch, and said first balance resistor,
• wherein said battery management system is configured to execute a method comprising:
• calculating, using said control unit, a value of a theoretical time constant corresponding to said first cell;
• determining a preset range of said theoretical time constant according to said value of said theoretical time constant;
• controlling, using said control unit, said first switch to successively turn off for a first time period, turn on for a second time period, and turn off for a third time period;
• controlling, using said control unit, said measure unit to measure a voltage value on said first capacitor at the end of said first time period, to produce a measured voltage value of said first cell;
• controlling, using said control unit, said measure unit to measure voltage values on said first capacitor at least at one time point in said third time period, to produce measured capacitance voltage values;
• determining, using said control unit, a value of a measured time constant according to at least one of said measured capacitance voltage values and said measured voltage value of said first cell;
• and
• determining, using said control unit, whether said battery management system is abnormal, wherein said battery management system is abnormal if said value of said measured time constant exceeds said preset range of said theoretical time constant.