How to test the quality of
18650?
The following introduces the routine quality tests used to verify the nominal battery specifications provided in the battery data sheet. Specific applications such as electric vehicles will require many more rigorous tests. Randomly select samples from each batch for testing.
Visual inspection: No defects such as deep scratches, cracks, rust, discoloration, or leaks.
Dimensional inspection: Check the accuracy of diameter and length.
Battery energy (power) test: This is measured through standard charging and discharging tests. Standard charging includes 0.5C constant current charging and 4.2V constant voltage charging, with the current gradually decreasing and finally stopping at 50mA. Standard discharge is performed at a constant current of 0.2C until a voltage of 2.50V is reached.
High drain charge discharge test: The charging rate of this example is 0.5C constant current to a voltage of 4.20V, with a termination current of 50mA. Then, the battery is discharged at a constant current of 0.5C to a low voltage of 2.50V. Rest the battery for 10 minutes after charging and for 20 minutes after discharging.
Cycle life: Charge and discharge the battery 500 times according to high consumption testing. A cycle is defined as one charge and one discharge. The discharge power of 501 ST should be greater than 70% of the initial battery capacity.
Storage test: The battery is charged at a standard rate and stored in a temperature controlled environment of 23 ° C ± 2 ° C for 30 days. After storage, the battery discharges at a standard rate. The remaining power should be greater than 90% of the initial power.
High temperature test: The battery is charged at a standard rate and stored in a temperature controlled environment of 60 ° C for 1 week. After storage, the battery is discharged at a standard rate and then cycled for 3 cycles to obtain recovered power. The power recovery rate should be greater than 80%.
Drop test: The battery is charged at a standard rate and dropped from a height of 1.0 meter onto a wooden floor. A total of 3 drops were performed, including 2 drops from each battery terminal and 1 drop from the side of the battery casing. There should be no leakage or temperature rise.
