"Did your Lishen cells come with a warrantee and QR code
documentation? If so for how long? Also, do you know if the problem
cell had a lower capacity, or if there was some other problem what it
Cells were sold to me as 280Ah Cells, and came with the wrong lables as they were Lishen 272AH cells. But the difference is so small I didn't worry too much, just kept quiet (them knowing you know and staying silent is an effective bargaining chip) Terminals were clean as was the QR code. This one cell had a solid blue vent cover, while the other 7 had a blue ring around them. After top balancing, I got 274Ah out of the pack with another cell than this one getting to low first. Vendor offered a five dollar discount per cell on a subsequent order because I got only 274AH instead of the 280AH. Batteries are still a good deal so I let it slide.
Now a month later, that cell with the blue vent cover is losing capacity fast. Last Friday, the pack cut out at 38% 4 weeks before it was 24% Top balancing does not help and at 99% charge the cell delta is 12mV. (I am new to this so I tried a few things to see if I had done something wrong.) A month ago I talked to the vendor and they said they would send a replacement cell, but it took them about a month to actually ship it.
I also ordered another 8 cells from them at the same time because I thought they had to match the manufacturer, (there is a cheaper vendor now, but I am not sure if they are reliable, Will and others are going to test...) I did that after reading about half a dozen posts saying I shouldn't mix them. I am stubborn, but some of the posts seem to be from people who, unlike me, know what they are talking about. So even though I see no reason why they can't be mixed, it is too expensive for my budget to experiment.
Now I have no idea why that cell is misbehaving, I checked the temperature, the connections etc The box it was in had been dropped during shipping, but I did not see any external damage on that cell (I did see some slight damage on another one) and the only difference is the colour of the vent cover.
I payed a week ago, they have not shipped them yet and after shipping, I will have to wait a couple of months for the shipment to arrive, it will give me time to build the pergola (with 8 more solar panels) "she who must be obeyed" wants. I did not expect perfect batteries from China, but I did not expect one cell to fail this badly. I am sure that with a little gentle persuasion, those Chinese vendors could well become decent suppliers.