I have just received 16 nos 280Ah Ninthcit cells, at least the cells have Ninthcit labels but the code on the cells refers to EVE.
I actually ordered grade A EVE cells from the supplier BLS Battery through AliExpress. The cells were courier delivered from their warehouse in Germany and they arrived within 10 days of shipment which is pretty quick for shipments from Germany to the Island of Ireland.
They were generally well packed but in a few boxes the terminals had partly penetrated through the cardboard box and punctured the plastic bag. Fortunately no terminals appear to be damaged.
I have measured the cell voltages and they are all within a range of 3.299-3.3020 volt..
There is no VISIBLE external damage and all the cells look clean. The QR codes are all in tact. All good so far. I still have to measure the impedances.
However some of the cells are obviously swollen but I have tried that quantify that by measuring the cells using vernier calipers with long jaws.
I have done that by determining the diameter of the cells across the width as I believe that swelling across the length is usually not an issue (correct me please if I am wrong!)
I first measured the width of the cells on both sides at the top of the cells (close to the terminals). I have found that at those locations the diameter is invariably smallest.
I then slid the vernier calipers to the bottom of the cells, again on both sides and noted the LARGEST dimension.
I put the results of this exercise in a spreadsheet and produced a delta between the smallest diameter and the largest one. I believe that represents the largest "bulge" in the cells.
Please note that I found quite a variation in the smallest width across the top of the cell (range 70.9 to 71.5mm), I assume that is the manufacturing tolerance.
The delta between the largest and smallest width was as follows:
One cell 3mm
One cell 2.8mm
One cell 2.4mm
One cell 2.2mm
One cell 2.1mm
One cell 2mm
Two cells 1.8mm
One cell 1.7mm
Two cells 1.2mm
One cell 1.1mm
Two cells 1mm
The other cells were under 1mm
Whilst bloated cells are obviously a concern I am not sure how much bloating is to be expected and how much would be unacceptable.
Can anybody quantify that? I have not been able to find any standards or specifications for LFP cells that bloating or swelling specifications/standards.
I am planning to put the cells in a pressure frame but I am concerned whether "flattening" the cells would cause internal damage.
As the cells are already charged to a 70% SOC I believe that they should not expand much more.
I would greatly appreciate any recommendations and advice.
Thanks
Mike
I actually ordered grade A EVE cells from the supplier BLS Battery through AliExpress. The cells were courier delivered from their warehouse in Germany and they arrived within 10 days of shipment which is pretty quick for shipments from Germany to the Island of Ireland.
They were generally well packed but in a few boxes the terminals had partly penetrated through the cardboard box and punctured the plastic bag. Fortunately no terminals appear to be damaged.
I have measured the cell voltages and they are all within a range of 3.299-3.3020 volt..
There is no VISIBLE external damage and all the cells look clean. The QR codes are all in tact. All good so far. I still have to measure the impedances.
However some of the cells are obviously swollen but I have tried that quantify that by measuring the cells using vernier calipers with long jaws.
I have done that by determining the diameter of the cells across the width as I believe that swelling across the length is usually not an issue (correct me please if I am wrong!)
I first measured the width of the cells on both sides at the top of the cells (close to the terminals). I have found that at those locations the diameter is invariably smallest.
I then slid the vernier calipers to the bottom of the cells, again on both sides and noted the LARGEST dimension.
I put the results of this exercise in a spreadsheet and produced a delta between the smallest diameter and the largest one. I believe that represents the largest "bulge" in the cells.
Please note that I found quite a variation in the smallest width across the top of the cell (range 70.9 to 71.5mm), I assume that is the manufacturing tolerance.
The delta between the largest and smallest width was as follows:
One cell 3mm
One cell 2.8mm
One cell 2.4mm
One cell 2.2mm
One cell 2.1mm
One cell 2mm
Two cells 1.8mm
One cell 1.7mm
Two cells 1.2mm
One cell 1.1mm
Two cells 1mm
The other cells were under 1mm
Whilst bloated cells are obviously a concern I am not sure how much bloating is to be expected and how much would be unacceptable.
Can anybody quantify that? I have not been able to find any standards or specifications for LFP cells that bloating or swelling specifications/standards.
I am planning to put the cells in a pressure frame but I am concerned whether "flattening" the cells would cause internal damage.
As the cells are already charged to a 70% SOC I believe that they should not expand much more.
I would greatly appreciate any recommendations and advice.
Thanks
Mike
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