Why do new energy electrics use 18650 batteries
18650 battery is an early, mature and stable lithium-ion battery, which is widely used in electronic products. Over the years, Japanese manufacturers have accumulated a lot of relevant experience in the process of producing 18650 batteries, so that the consistency and safety of the 18650 batteries produced have reached a high level.
In contrast, cascading lithium-ion batteries are far from mature, common square batteries, soft pack batteries, even if the size, size, and position of the tabs are not uniform, the production process of battery manufacturers cannot meet the conditions, and most of the manual control, The battery consistency is that the battery is not at the level of the 18650. Managing a large number of cells in series and parallel will not allow each cell to perform better if the consistency of the cells is not up to par, and the 18650 cell can solve this problem.
To sum up, the 18650 battery has a small capacity and a large number of cells (7104 for the S type), but the consistency is good. Cascade cells can be increased (20ah 60ah), and the number of cells can be decreased, but the consistency is poor. In contrast, it is very difficult to invest a lot of manpower and material resources with battery suppliers to improve the production process of cascaded batteries. So when it comes to developing the Roadster and Model S, Tesla's only option is to buy batteries from the market and develop its own battery system. The technical challenge of developing a battery system that manages more than 6,000 units with good consistency should be less than that of more than 200 units with poor consistency. Even if the number of individual batteries increases, it will be easier to manage if they perform reliably.
