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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
 
cells.
 
  • 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.

latest company news about How to Distinguish Grade A and Grade B cell - Prismatic Cell 0

  • 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.

latest company news about How to Distinguish Grade A and Grade B cell - Prismatic Cell 1

 

  • 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: allen@seplos.com.

 

For detailed video, please check below:

Seplos 3.2V 100Ah LiFePO4 Prismatic Cell: https://bit.ly/3mQz9pI