Right but doesn’t the data sheet imply pressure will not reach damage potential in a rigid fixture under normal usage..
I don’t think the small extra cost either way should sway the decision of a DIYer. Doing what best however to get more cycles might matter. That’s if the user wants the best life for the cells instead of simply thinking calendar aging will happen first..
Higher pressure thru the SOC might stop unwanted expansion that users are reporting when using springs and 300kgf. Remember your c-rates and charge cycles are low/not fast so you are not seeing as much expansion as two other users commenting on this thread that use springs.
.
Yes cheaper. Have seen just strapping used. To allow some expansion instead of rigid fixture and still claiming 10k cycles..
If what you seem to be hoping / suggesting were true, you’ll need to explain to me why EVE didn’t clamp their fixture to 600kgf if not 1000.
Their spec for clamping force is not ‘>300kgf’, it’s 280kgf to 320kgf.
The idea that higher clamping force than 300kgf can extend cycle life is misguided.
EVE has shown you how you can get 6000 cycles to 80% of initial capacity by building a rigid structure.
Without having stated so explicitly, they have also suggested that you can safely use that structure to cycle a cell all the way to 60% of initial capacity without needing to worry about pressure when charging increasing past the point where it could start causing defects.
So I agree with the conclusion that EVE’s new datasheet gives the ‘all clear’ on using a rigid fixture (assembled according to their specifications).
It’s the idea that you are going to get fewer cycles in a fixture maintaining 280-320kgf throughout the full cycle that I find misplaced.
If anything, fully-depleted cells in a rigid structure will be under less pressure than fully-depleted cells in a constant 300kgf structure, so ‘expansion’ and internal deformation could be worse.
EVE suggested a constant 300kgf fixture was required for increased lifetime in 2021 and my read is that enough battery manufacturers complained about the added complexity and cost that would involve so EVE came out with all tjus additional detail showing constant force was but required to get the same cycle life.
This datasheet makes it clear how you can build a simple rigid fixture to achieve a full 6000 cycles to 80%.
But it include nothing to suggest tgat a constant 300kgf will deliver fewer than 6000 cycles to 80%.