It’s just great to have such a market. Better for the environment too.
@Richard_Mackay what would you estimate to be the remaining cycle life of these cells? I’m thinking we could use the Revov 2nd life products as a guide to the Maximum likely life?
They state this currently as 3500 cycles.
I haven’t a clue!
I have always asked which brand the cells are because this will determine the ultimate performance of the batteries (not the company that assembles the cells & BMS etc.)
How would you calculate the lifespan and then the remaining capacity? Are their detailed calculation’s for each brand, do they differ and how does chemistry play a role?
Like all products in the second hand market this will be determined by the make/model.
That’s why this info is pivotal…
Revov 2nd Life is 100% factory tested and vetted backed by a 10 year guarantee.
Completely different league.
DIY seller of 2nd hand cells, how long is a piece of string?
There is absolutely no way, far as I can determine, to ascertain the remining cycles.
Yes you can do a test, but no guarantees whatsoever.
You will win sometimes, you will lose sometimes.
Accept that and manage the cell replacements as and when required, if required.
Sorted.
Absolutely. It’s the only way. Overprovisioning
And these are 2nd hand Grade B - so like Grade C?
Titbit:
What I’ve see on an old bank, cells by no means batch matched, one must accept upfront you will need a more powerful balancer, dedicated one like i.e. a NEEY or some such, to keep the cells kinda in line.
Saw that, Andy did same, with our Frankenstein banks.
We both tried the theory that you can have a old 2nd life 100ah cell in the same bank as, my case, as a new 280ah cell.
Just adjust the charge amps low enough for the 100ah cell.
Works fine for temporary, not for permanent setup.
Like Grade F, for Fail. 
With wisdom and careful management, even a Grade F earner can achieve success.
One rule I deduced: (was bored and had to wait for the new cells to arrive)
If a cell/s starts bulging, let them go and be quick at that.
Lots of wisdom flowing here!
I always tell this story of a time when we still had graded handwriting classes in school. It was grade 4. I pretty much always got a D for my handwriting. One day I decided to make an effort. I was extra careful, extra precise, took more time to form the letters. It was beautiful. I was so proud of it. A week later I got back my mark. I had improved to a C.
At that point I decided a D is good enough. If all that effort only produces a mild improvement, it is not worth it.
I’m sure that applies to many other things in life as well 
If the BMS says that, it’s usually because the MOSFETs are not rated for a high enough voltage to allow that. Basically, if there is a fault and the one BMS disconnects either the input or output MOSFETs, it can see up to the series stack voltage across it. Then usually the MOSFET will fail in short-circuit…
So if it’s not rated for series connection, don’t even consider it. The only solution is to rip out the BMS and use a different one.