With all due respect: checking v alone does not give you soh only soc.
The soh is pretty important.
Here is how it should be done in my opinion:
Each separate cell must be charged to full (8.3v), then discharge to there minimum voltage (5v)with a discharger that counts watts or ah.
Optimum is 41ah ofcourse--->100% SOH.
Very good would be a minimum of 32,8ah left------>80% SOH
Duable:60-80% soh--->24,6ah- 32,8ah
Those numbers you write down on each cell (including date of testing), also handy for future testing (after 3 years or so)to see how your wall is holding up.
Before stacking/connecting your cells you can calculate for each string how much it holds total, so you can build all the strings in the same capacity.
I would be really a waste of time if there would be one cell with just 20% (8ah)of capacity left, that cell will break your whole powerwall.
Make 7 packsthat are close to each other and start building from here, with the lowest SOH on top.
This is my favorite tester:
https://nl.aliexpress.com/item/4001...earchweb0_0,searchweb201602_,searchweb201603_
Oke it can do max 3A an hour discharge, but it will give you the numbers you need.
It will take a 10h to 15h to complete for each cell, just buy 10 or so,they dont cost much
To charge if needed:
https://nl.aliexpress.com/item/32872607362.html?spm=a2g0s.9042311.0.0.27424c4druX18I
Before connecting them in series let them balance like slimf said, by just connectingeach string parallel and let them equalize.
That will be a very good start, the Batrium can only do so much, but equalizing would give it a good start.
With this little extra effort you will get the MAX capacity and lifespanout of your powerwall.
This is just some advice, it is your wall.
Looking forward to see the rest of the build.
With best regards Igor