Battery safety identifying method and method for setting hazard levels of battery internal short circuit and warning system using the same

A battery safety identifying method, comprising:

• detecting a voltage drop and a voltage drop rate when a battery is abnormal;
• detecting a duration time of the voltage drop and a voltage recovery ratio within a limited time interval when the battery is abnormal;
• detecting a surface temperature or a temperature rise when the battery is abnormal;
• and
• setting a plurality of hazard levels of battery abnormality and at least one protection mechanism according to the voltage drop, the voltage drop rate, the voltage recovery ratio, and the surface temperature or the temperature rise;
• wherein, when a first condition is met, the battery abnormality is set as a mild hazard, when the first condition is not met and a second condition is met, the battery abnormality is set as a moderate hazard;
• when the first condition is not met and the second condition is not met, the battery abnormality is set as a severe hazard, and the at least one protection mechanism is activated.