The Principle and Function of Battery Capacity Testing and Sorting

What is lithium ion battery capacity testing sorting?

There are two explanations for lithium-ion battery capacity test and sort.

The first explanation: Battery capacity sorting and performance filtering. Lithium battery capacity sorting through computer management to get the data of each detection point, so as to analyze the size of the battery capacity, internal resistance and other data, determine the quality grade of lithium battery, this process is capacity testing and sorting. After the first capacity test and sorting of the lithium battery, it needs to be left for a period of time, generally not less than 15 days. During this period, some inherent quality problems will appear.

The second explanation: After a batch of lithium batteries are made, although the size is the same, the capacity of the batteries will be different. Therefore, the battery must be fully charged in the battery formation machine according to the specification, and then discharged at the specification current. The time it takes to discharge the battery times the discharge current is the capacity of the battery. Lithium ion batteries are qualified only when the test capacity of the battery meets or exceeds the design capacity, and the battery capacity less than the design capacity is not qualified. The process of sorting qualified batteries through capacity testing is called battery capacity testing and sorting.

Formation of lithium ion battery: Generally refers to the implementation of a series of technological measures for the first charge of the battery to stabilize its performance, including small current charge and discharge, constant temperature and standing.

Principle of lithium ion battery capacity testing and sorting:

Lithium ion battery capacity testing and sorting is through battery formation machine to complete. The functions of battery formation machine simply like a charger, but it has more functions, and it can charge and discharge a large number of batteries at the same time.

What is the role of capacity testing and sorting for Lithium ion batteries?

TOB New Energy battery formation machine can make each channel start and stop independently, each channel has an independent constant current source, constant voltage source, real-time sampling of current and voltage, to achieve constant flow constant voltage without disturbance continuous switch, can be used for cycle life test. In addition, it can also classify and group lithium-ion batteries, and select cells with the same internal resistance and capacity for combination. When combined, only those with similar performance can form a lithium-ion battery pack. Power packs, for example, often require dozens to thousands of battery cells to meet the energy needs of electric cars. This has a high requirement for the consistency of single battery cells.

Accuracy requirements for formation and capacity sorting of lithium ion batteries:

In order to improve the cycle life, stability, self-discharge, safety and other electrochemical performance of lithium ion battery, it is necessary to strictly control the consistency of lithium ion battery or accurately evaluate the battery grade, therefore, it has high requirements on the measurement accuracy of current and voltage for the battery formation and capacity testing equipment. Limited by the sensor's acquisition accuracy, the current and voltage measurement accuracy of chemical capacitance equipment on the market is generally about 1/1000. For battery formation, the higher the control accuracy of current and voltage, the better the quality of lithium ion battery products. The accuracy of current and voltage sensor is more than 1/10,000 is the ideal choice.