There is more than one weak cell shown in those fully discharged cell voltages - I count about 5 weak cells that are 200mV or more below the average voltage. It's difficult to tell looking at a table of numbers though.
If possible I would recommend using Canion to get a screenshot of the voltage graph when near discharged as it is much easier to evaluate in visual form. For example here is a fully discharged graph from my car a year ago:
As can be seen, cells 25, 69 and 70 are weak on my car with 25 and 70 being the worst. They also have high internal resistance which shows as an excessively high voltage during rapid charging which limits peak charging rate prematurely.
The 25.8Ah reported on your car is a severely degraded battery. (new is about 46Ah) Mine has done 50k miles and is down to 35.2Ah which I already consider to be significantly lower than it should be for the mileage. (I also have some weak cells) However your low figure may be the result of just a few bad cells.
The problem with replacing them is that the replacements have to be at least as good as the good
cells remaining in the pack, and there is no easy way to know what the Ah capacity of the best cells in your pack are.
Any second hand cells are likely to be degraded and may be even worse than the ones you're trying to replace. I found some second hand cells for my car but when the seller tested them they were down to about 28Ah so were considerably worse than even the weak ones in my pack! This despite them coming from a car with half the mileage as mine. (Needless to say the purchase was cancelled)
So beware of second hand cells unless the seller is an EV battery specialist and willing to measure their Ah capacity and vouch for them.
AleksM wrote:But the fact that the cells do not fall to the required level of 2.8 V is also caused by a bad cell ??
and what can be done now?
Not sure what you mean by "required level of 2.8 volts" ?? These cars do not discharge the cells this low. Normal cutoff voltage at 0% SoC for an 88 cell car is 320 volts for the pack or about 3.64 volts per cell. If the pack is badly degraded the cutoff voltage may be lower than 320 volts however.