Why does the 18650 battery have no output?

Why does the 18650 battery have no output?

When receiving feedback from a customer that the cylindrical 18650 lithium battery pack cannot charge or has no output (for example, the Sanyo 18650, 11.1V lithium battery pack), the battery is now confirmed, tested and analyzed as follows:

1) Confirm the production date of the battery;
2) Use a multimeter to check the voltage of the battery pack and ensure that the output voltage is 0V;
3) Testing the battery charging function with a DC source showed no response;
Note: If the voltage of the battery cell is too low and there is no output voltage after the low-voltage protection of the protection board, it can be charged and activated;
4) Disassemble the batteries and confirm that all three sets of batteries use the same type of protective board, and the battery cells are Sanyo cells:
A、 After testing the functions of the protection board (overcharge, overdischarge, overcurrent protection, etc.), it was confirmed that its function is normal;

B、 Inspect the battery cells, with each group consisting of battery cells with a voltage lower than 1V.

Summary:
Based on the analysis of battery disassembly and testing, it is preliminarily confirmed that the performance of the battery pack protection board is normal, which is caused by poor battery cells. The disassembly of the Sanyo 18650 lithium battery is shown in the following figure.