How to Distinguish Grade A and Grade B cell - Prismatic Cell

December 10, 2019
Latest company news about How to Distinguish Grade A and Grade B cell - Prismatic Cell
According to an analysis, China shares 73% of global lithium cell manufacturing capacity. Therefore,
to know the Chinese battery market is a critical part for those who enrolled in this industry. There are
many factories producing LiFePO4 battery cells in China. And the quality standards are different. And
every supplier claimed that they sell Grade A cells. What exactly are Grade A and Grade B cells?
The best way to know a cell is Grade A or Grade B is to check if the cell meets the manufacturers’
specifications. This article will introduce some important specifications on a datasheet. By comparing
those specifications with the testing data. We’ll know the differences between Grade A and Grade B
  • Appearance


The first thing we can do to check a cell is to check its appearance. Each cell was produced with a
unique QR code as a proof of identity. Which also makes it more convenient for the manufacturers
to offer after-sale services. And as we mentioned in the last post, Grade B cells are categorized as
unqualified ones, they usually do not offer a warranty. That’s why they will scrape off this QR code.
So if you find a battery cell with QR code concealed. Mostly it is Grade B battery cell. However, all
Grade B cells will be covered with a new insulated sheet. So if there are no obvious signs of QR
code outside, you’ll need to tear off the insulated sheet.

Tips: It does not mean that all battery cells with QR code are Grade A cells.

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  • Dimension&Weight

As dimension&weight will be slightly different at different SOC percentage, it would be necessary for


you to confirm with the supplier of their testing SOC percentage. Then measure the size at the same


SOC percentage level. And compare the measured value with the one they offered on the datasheet.


  • Capacity

Capacity is usually tested at the temperature of 25℃, charging and discharging rate of 1C. Record


the real tested capacity. And compare these two data.

Note: Different temperatures will affect the capacity of lifepo4 battery cells. So some manufacturers


will send you the cell with its capacity a little bit higher than it should be. If your testing capacity is a


little bit higher than the datasheet. If only there aren’t too many differences. That will be alright.


  • Internal Resistance


Firstly, confirm the testing environment with suppliers. Including temperature and SOC conditions.


AC internal resistance is usually tested at the frequency of 1000HZ. An AC internal resistance meter


will help you with the testing. For other manufacturers, they will provide DC internal resistance. Then


you may need a multimeter. Compare the real tested data with the one offered in specifications.

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  • Self-discharge Rate

The self-discharge rate differs at different SOC state. For example, the voltage decrease quicker at


100% SOC than at 50% SOC. So before testing the self-discharge rate, check the battery


specification about the testing SOC state first.



  • Capacity Recovery

To test the capacity recovery rate, you just do a 100% DOD charging and discharging cycle. And


check if the capacity recovery rate meets the datasheet.

For example, for a 3.2v 100ah battery cell, if the recovery rate is 95%. We have tested the capacity


at the beginning. It is 100ah. Then after all the tests, we do a 100% DOD charging and discharging.


Then the capacity should be more than 95ah. If yes, the battery capacity recovery rate meets the


datasheet. It's Grade A quality cell.



  • Conclusion

What we are doing is to compare the testing data with the specification of the cells. So we can trust


the datasheet or supplier. After all the tests and comparison, if all the data meet the specification or


datasheet, it is Grade A cells. If not, it is grade B cells.

Ask your supplier for some samples. And test whether it is Grade A or Grade B cells? Any other


questions, please contact us at:


For detailed video, please check below:

Seplos 3.2V 100Ah LiFePO4 Prismatic Cell: