What is lithium battery capacity grading?
Lithium battery capacity classification: a simple understanding is capacity sorting, performance screening and grading. When the capacity of lithium batteries is divided, the data of each detection point is obtained through computer management, so as to analyze the data such as the size and internal resistance of these batteries, and determine the quality level of lithium batteries. This process is capacity grading. After the lithium battery is divided for the first time, it needs to stand for a period of time, generally not less than 15 days. During this period, some internal quality problems will appear.
After a batch of lithium batteries are made, although the size is the same, the capacity of the batteries will be different. Therefore, the device must be fully charged according to the specification, and then discharged (finished) according to the specified current. The time it takes to discharge the electricity is multiplied by the discharge current is the capacity of the battery. Only when the tested capacity meets or exceeds the designed capacity, the lithium battery is qualified, and the battery with less than the designed capacity cannot be regarded as a qualified battery. This process of screening qualified batteries through capacity testing is called capacity grading.
Lithium battery formation: generally refers to the implementation of a series of technological measures on the first-time charged battery to stabilize its performance, including charging and discharging with a small current, and standing at a constant temperature.
The principle of lithium battery capacity grading:
The capacity grading of lithium batteries is accomplished through the battery formation and grading system (because the basic principles of formation and grading are the same, the functions of formation and grading are integrated in the same cabinet, called formation and grading system), and the functions of formation and grading system In fact, it is like a charger, except that it can charge and discharge a large number of batteries at the same time.
When the capacity of lithium batteries is divided, the data of each detection point is obtained through computer management, so as to analyze the data such as the size and internal resistance of these batteries, and determine the quality level of the battery. This process is capacity grading.
What is the role of lithium battery capacity grading?
The produced lithium batteries cannot be sold immediately, and should be stored in the warehouse for at least 15 days. During this period, some inherent disadvantages will appear, such as excessive self-discharge, etc., and the batteries that have reached the shelf life in the warehouse , after getting the order, take it out again to test and divide the capacity again, that is to say, charge and discharge again, eliminate the capacity that cannot reach the level, or have quality problems, and then hand it over to the sales department to maintain about 50% of the power, and finally To the mobile phone battery block assembly factory.
The battery cells that will be used for lithium battery assembly are converted into separate capacity again. Through this process, some batteries that do not meet the requirements can always be picked out and returned to the battery factory. After passing the lithium battery detection mechanical test, it can be seen that the battery cell has been charged and discharged, and it is "electric". So when you get the battery, there are two bars, which is normal.
Each channel can be single-point start and single-point stop according to the battery capacity, and the response speed is fast. Each channel has an independent constant current source and constant voltage source, real-time sampling of current and voltage, and continuous switching from constant current to constant voltage without disturbance. It can be used for cycle life test.
Classification and grouping of lithium batteries is to screen out monomers with the same internal resistance and capacity for combination. When combining, only those with very close performance can form a lithium battery pack. For example, in order to meet the energy demand of electric vehicles, the power battery pack often needs dozens to thousands of batteries. Affected by the complexity of the system, the behavior of the battery pack has its own uniqueness. It is not a simple single battery. The performance of the lithium battery pack can be obtained by the addition and subtraction.
Formation and capacity grading accuracy requirements of lithium batteries:
In order to improve the electrochemical performance of lithium batteries such as cycle life, stability, self-discharge, and safety, it is necessary to strictly control the consistency of lithium batteries or accurately evaluate the battery grade, so the measurement accuracy of the current and voltage of the formation and capacity separation equipment There are very high requirements, limited to the acquisition accuracy of the sensor, the current and voltage measurement accuracy of the chemical capacitance equipment on the market is generally about one thousandth. For formation, the higher the control accuracy of current and voltage, the better the quality of lithium battery products, and the accuracy of current and voltage sensors above one ten-thousandth is an ideal choice.
The batteries have been sorted and checked before leaving the factory, and the sorting cabinets in the lithium battery factory are sorted. Lithium batteries are widely used in various fields such as electronic products due to their excellent performances such as high energy density, high voltage, high cycle, high safety, and environmental protection. Therefore, it is very important to ensure the consistency and reliability of lithium battery products.
Acey new energy is a professional supplier specialized in Lithium Battery Pack Assembly Machine, such as battery capacity grading machine, battery insalution paper sticking machine, battery sorting machine, BMS tester, battery spot welding machine, battery comprehensive tester, battery pack charge and discharge aging tester, etc and we provide one-stop solution for cylindrical battery pack assembly line. If any interested, please feel free to contact us.
