From a material perspective, battery cells are rare earths + metals + precious metals. Several major battery manufacturers have been importing rare earths from China (the main producer of rare earths is China). Since rare earths are symbiotic minerals, even with sophisticated purification technology, every The materials produced each time have slight composition differences (mainly impurities). At the same time, the key material - cobalt oxide also has its own characteristics. Since cobalt oxide has weak radioactivity and a half-life, and is particularly sensitive to impurities, then every time The battery cells produced are made of rare earth materials from different origins, and the quality is different. The small difference in impurities is enough to affect the stability of the lithium lattice and cobalt oxide. This means that the same batch of battery cells is produced, and the manufacturer must separate them. The reason for labeling is the capacity.
When battery cell manufacturers produce the same batch of batteries, they will be classified according to the discharge test performance of the batteries into four categories ABCD (Sanyo's distinction method, because the distinction methods of Sanyo and Panasonic have actually become industry standards). A=2000mah, B=2200mah, C=2400mah, D=2600mah. Mark the ABCD distinction code on the battery, and then distinguish it on the color of the battery protective gas cap (the battery will produce gas when it is discharged, and the positive electrode of the battery has A protective cover. When the battery deflates to a certain amount, that is, when it is about to reach the design life, the gas will push the cover open, causing the battery to decircuit). This is the source of ABCD. Since Sanyo and Panasonic Strength has become the default way of differentiation in the industry.
A-grade battery cells: Generally, factories that use battery cells place orders directly to the battery cell factory. The battery cell factory arranges production according to the factory's own production capacity and technical capabilities. After a series of battery cell manufacturing processes, the battery cell factory finally produces Batteries, delivered to customers. Before placing an order, the battery production factory will generally communicate battery capacity, thickness, length, width and other parameters. Then the battery that is made completely according to the order's standards is called product A.
B grade batteries
Any factory producing products will inevitably have a defective rate. Then this defective rate determines the vitality of a factory. In the lithium battery industry, based solely on technology, ingredients, etc., there will not be a big difference between first-tier lithium battery factories and third-tier lithium battery factories. However, in the production process and manufacturing process, there will be There is a huge gap in the defective rate. First-tier manufacturers can achieve about 2%, while second- and third-tier manufacturers may achieve 5-10%. It is precisely because of this defective rate that B products are created.
In fact, product B only has a slight difference in capacity, or the length, width and thickness do not meet the order requirements, but the performance is definitely not compromised, but the price is cheaper than product A. Therefore, there are many manufacturers. Sometimes product B is shipped directly, but the capacity is Mark it lower. In addition, product A is generally placed in the warehouse and if it is not shipped for 3-6 months, it is also called product B. Of course, this is just a popular term.
C grade batteries
Product C actually means that the batteries of product B have been stored in the warehouse for more than 8 months. If they are still not shipped, they can be called product C. The products of product C are caused by self-discharge and dust due to long storage time. Due to the aging of water vapor, the most common situation for C-grade batteries is swelling of the package. Sometimes the package swelling occurs when charging, and sometimes it occurs due to leakage or short circuit. C-grade batteries are generally only about 50-60% cheaper than A-grade batteries of the same model, and good ones can reach 70%. C-grade battery cells are less safe. In addition, C-grade battery cells are not durable. After several cycles of charging, their performance will be greatly reduced. Many friends had a feeling when they bought mobile phone batteries. The battery they just bought seemed to have a good battery life, but after using it for a month, they found that it didn't work. Basically, they use C-grade batteries.