The rated voltage of a lithium ion battery is generally 3.7V due to a change in material, and 3.2V is a lithium iron phosphate (hereinafter referred to as a ferrophosphorus) positive electrode. The international standard for termination charging voltage when fully charged is 4.2V, and phosphorus iron is 3.6V. The termination discharge voltage of the lithium ion battery is 2.75V to 3.0V (the domestic battery factory gives the working voltage range or gives the termination discharge voltage, and the parameters are slightly different, generally 3.0 to 2.75V, and the phosphorus iron is 2.5V.). Continued discharge below 2.5V (phosphorus iron 2.0V) is called overdischarge (the international standard is the lowest 3.2v, ferrophosphorus 2.8v), low voltage over-discharge or self-discharge reaction will lead to the decomposition and destruction of lithium ion active substances, not Must be restored. Any form of overcharging of a lithium-ion battery can cause serious damage to the battery performance and even explosion. Lithium-ion batteries must avoid overcharging the battery during the charging process.