In recent years, more and more products such as smart phones, digital cameras, portable audio devices and Bluetooth devices use lithium batteries as the main power source. Due to the advantages of small size, high energy density, no memory effect, high cycle life, high voltage, and low self-discharge rate, lithium batteries are different from nickel-metal hydride batteries and nickel-cadmium batteries. Lithium batteries must consider the safety of charging and discharging, because overcharging and overdischarging of lithium batteries will cause damage to lithium batteries. What is the harm of battery overdischarge to lithium batteries?

1. What is overdischarge

The so-called overdischarge means that when the battery is discharged, the stored electric energy is gradually released and the voltage drops slowly. When the voltage drops to a certain value, the discharge should be stopped, the battery should be charged, and the energy storage state of the battery should be restored. Continue to discharge below this specified value, that is, excessive discharge.

2. What harm does overdischarge do to lithium batteries?

Overdischarge of lithium batteries often brings catastrophic consequences to lithium batteries, especially high current overdischarge or repeated overdischarge, which has a greater impact on the electrical properties of lithium batteries.

Just like a person loses 300 to 500 ml of blood at a time, it will not affect people's health. However, once the blood loss is too much, the normal body function of the person cannot be maintained, and to a certain extent, the person will die. For lithium batteries, excessive discharge will increase the internal pressure of the lithium battery and destroy the reversible function of the positive and negative active materials. Even if it is remedied by recharging, it is difficult to fully recover. The natural capacity is significantly weakened, and the lithium battery decays to a certain extent and is scrapped. There is no way to recover a spent battery.

Therefore, in order to avoid the harm of over-discharge of lithium batteries, protection parameters should be set according to the characteristics of lithium batteries in the early stage, and in the later use, the "Regulations for the Use of Lithium Batteries" should be strictly followed in the instruction manual.