Why does deep discharge shorten the life of lithium batteries?

Frequent deep discharge will shorten the service life of the lithium battery. Under normal circumstances, the lithium battery of an electric vehicle can be used for 2-3 days when it is fully charged. However, when using the lithium battery, it is necessary to maintain the full state of the lithium battery as much as possible to avoid excessive Use lithium batteries. Deep discharge is not completely impossible, and an occasional deep discharge still promotes and restores the capacity of the battery. How long can lithium batteries be used? In general electronic products, the design life of lithium batteries is usually 5-20 years, and the average in practical applications is about 8 years. Under the current technical level, the service life of lithium batteries in electric vehicles is usually only 3-5 years. The cost of the vehicle is usually 20%-60% of the entire equipment, of which the cost of the electric vehicle battery accounts for about 40% of the entire vehicle. The service life of a lithium battery is usually designed to be around 1,000 times, and it is usually 3 years according to a normal high-frequency commute. Lithium phosphate batteries can be charged up to 2000 times, and the cycle life is relatively longer, but the capacity density is always lower than that of lithium ion and ternary lithium batteries. Generally speaking, the cycle life of a lithium battery is usually determined by the number of times it is fully charged and emptied. Except for possible failures of the lithium battery, when the lithium battery reaches or exceeds the designed number of uses, it all means the end of the life of the lithium battery. At this time, the performance of the lithium battery is far less than 60% of the initial state, and the energy consumption is high. The power storage capacity is very limited, and the probability of heating and accidents will increase accordingly. Lithium batteries in this state are not recommended for any other purposes. There is still room for decomposing and recycling. How to extend the life of the lithium battery ① Charge it in time, and recharge the lithium battery when the power of the lithium battery is below 30%. ② Avoid fast charging. The only way to fast charge is to increase the charging current. The current lithium battery technology still has no greater breakthrough in charging. Although fast charging can be achieved, the high heat generated will directly affect the service life of the lithium battery. ③Regularly check, even if the abnormal state of the lithium battery is found and repaired. Why does deep discharge shorten the life of lithium batteries? There is a scientific basis for starting to charge the lithium battery with 30% of the power, especially for power batteries. When the lithium battery is discharged, the load discharge will cause the lithium battery to have a certain degree of voltage drop, so as to realize the current discharge according to the limit of the protection board. However, when the capacity of the battery increases with the depth of discharge, the performance of the battery also decreases, but the demand for current of the device is constant, such as a battery with a capacity of 3000mAh, if the device needs a current of 1.5A to drive , Then the battery can be satisfied at a discharge rate of 0.5C when it is fully charged, but when the battery capacity is left by one-third, if the power of the device is to be met, the battery needs to be discharged at a rate of 1.5C. This ratio can be based on one-fifth of the power, when the state of one-tenth, the discharge rate will be doubled. Of course, if the discharge rate of the lithium battery itself is insufficient, the state of the lithium battery will be discharged at the limit. In operation, the lithium battery discharged in the extreme state will generate high heat, and there will be a heat accumulation effect to generate a higher temperature. Eventually damage the battery. In severe cases, the lithium battery will be scrapped, and even serious safety accidents will occur. However, in general, the lithium battery design will select a suitable lithium battery cell for combination according to the power of the device, and reasonable BMS control parameters Settings, but still apply to the above content. Lithium batteries are usually overloaded when running at low power. Therefore, frequent deep discharge is harmful to the life of the lithium battery. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous post: The new cathode coating can extend the life of lithium-ion batteries and improve safety!