Usually, you can find a sheet on the specification of 18650 cells in a website. However, this sheet is only telling you of a common basic specification for a cell. It is hard to even impossible for you to know whether you will get the right reliable cells.
As we know, the qty per daily production line for each 18650 is at least 100,000 pieces. All the cells look the same. But the qty probably is different. Probably some are kept in the designed level of specification, some others not. This is the production stability or product uniformity. If all cells are among the designed specification, we can say the stability of production is good. We also can say the production uniformity is excellent. That means you will get the same quality for all cells you taken from this cell makers. This is the stability and uniformity for a batch of production.
On the other hand, we have to evaluate the production stability and product uniformity for the factory’s running production for different batches. If the factory can keep the production stable and production uniform for different batch production, we can say the quality of the factory operation, production, and product is excellent.
Then the key question comes out. Yor will ask how we can know whether my supplying cell maker’s production stability and product uniformity is OK. Forever EV will show you one example based on 2000mAh 18650 for your reference.
Basically, you can check the points with your suppliers and get to know the stability and uniformity of a cell.
- What is the impedance or inter resistance for the cell?
- How many pieces of cells are tested for the impedance? And how about the testing result? Forever EV’s factory picks up 10,000 pieces of cells from 100,000 pieces for this testing and found all internal resistance is kept in the targeted range.
- What is the tested voltage for the cells?
- How many pieces of cells are tested to evaluate the stability of voltage? Forever EV’s factory picks up 10,000 pieces of cells rarely and found all cells are in the designed voltage.
That is to say, Forever EV’s 2000mAh 18650 Li-ion cells are with a stable impedance/internal resistance and voltage from the batch of 100,000 pieces. The clients don’t need to worry they will get different-level quality cells from us. The clients will always get the stable quality and uniform product from Forever EV!