When the battery manufacturers produce the same batch of batteries, they will be classified according to the discharge test performance of the batteries, which are divided into four categories: ABCD.
Grade-A is the name of the high-quality standard of the battery. Its battery materials, technology, energy storage, stable charge and discharge, specifications, and constant temperature standards are all high-quality standards in the industry.
Grade-A battery cells generally place orders directly from the factory that uses the cells to the cell manufacturer. The cell manufacturer arranges production according to the factory's production capacity and technical capabilities. After a series of battery cell manufacturing processes, the battery cell is finally produced and delivered to the customer. Before placing an order, the battery manufacturer generally communicates parameters such as battery capacity, thickness, length, and width. Then the battery made completely according to the standard of the order is called a Grade-A cell.
However, due to the boom in the new energy vehicle market, EV batteries are in short supply. At the same time, Grade-A cells are generally given priority to new energy vehicles, so it is difficult to directly buy Grade-A batteries from major manufacturers in the market.
If any factory produces products, there must be a defective rate. Then this defect rate determines the vitality of a factory. In the lithium battery industry, purely based on technology, ingredients, etc., there will not be a big gap between the first-line lithium battery and the third-line lithium battery factory. But considering the production process, there is a big difference in the defect rate of manufacturers, and the first-tier manufacturers can achieve about 2%, while the second and third-tier manufacturers may achieve 5-10%. It is precisely because of this defect rate that Grade-B cell is created.
Grade-B cells are only slightly different in capacity, or the length, width, and thickness do not meet the order requirements, but the performance is not compromised, and the price is cheaper than Grade-A cells. In addition, Grade-A cells are generally placed in the warehouse and if they have not been shipped for 3-6 months, they're also called Grade-B cells. Of course, this is just a popular saying.
Grade-C cells are below average in every respect, lower than the standards of Grade-A and Grade-B cells. Grade-C Cells are very different from Grade-A cells in terms of energy storage, stable charging and discharging efficiency, battery materials, technology, and repeated charging and discharging.
If the Grade-B cells have been stored in the warehouse for more than 8 months, if they are still not shipped, they can be called Grade-C cells. Due to the long storage time of the Grade-C cells, the performance begins to decline with self-discharge, dust, and water vapor aging, so the most likely situation for the Grade-C cells is to increase the package. The expansion of the battery sometimes occurs during charging, and sometimes occurs during liquid leakage and short circuit. Grade-C cells are generally only about 50%-60% of the same type of Grade-A cells, and the best ones can reach 70%. Grade-C cells are less safe. In addition, Grade-C cells are not durable, and after several cycles of charging, the performance will be greatly reduced.
The easiest way to tell the difference between Grade-A and Grade-B cells is that the Grade-A cells have the original manufacturer's test report. The data should include the internal resistance, voltage, capacity, and product code of each cell (usually the same information as on the QR code). Without these, 99% are probably grade B batteries. Usually, some Grade-A cells are recycled from electric vehicles and reused, and such cells are usually treated as Grade-B cells.