My cells aren't anywhere near 90 degrees Celsius.
And vice-versa. But the overwhelming evidence shows that there are no problems - arguably millions of batteries with solid bus bars with no reported problems as a result of solid bus bars.
In an environment such as an EV, I agree that building with flexible makes more sense - an EV is subject to far worse conditions than most of the batteries we're using/building.
I don't argue this. All I've stated is that I observed 0.1-0.5mm of expansion from 0-100 SoC (and 40F - 85F) and that I believe that's sufficiently small to use solid bus bars.
Still, look graph, temperature is a parameter as I said, contrary to your affirmation. Do not need to go to 90°C.
No there is not vice versa, it's not symmetric, "That you do not see problem with rigid busbars do not prove that there not any".
1- If you can see a problem there sure is one
2 -If you can't see a problem there still can be one hidden, specially on this case where you can see the internals.
Millions of case is not enough to prove something. One counterexample is enough to prove the falsity.
What I mean is that you take a risk, you are confident tha you took enough test to globaly cover your use. And yes it can be sufficient most of the time. But seeing the potential consequences...I feel it's not enough.
" I observed 0.1-0.5mm of expansion from 0-100 SoC (and 40F - 85F) and that I believe that's sufficiently small to use solid bus bars."
From my point of view..0.5mm is already too much.
Let's imagine your charger for a problem and overcharge....now batteries take 2mm on each side of them...and it's not even that much, that's now 4mm distance increase that busbar are refusing to give and transferring to terminals...
I'm not saying what you should do, it's your life. Just that in MY mind those risk are not worth the price differences, reason I discuss the case, you did a good job with the compression springs and all, I'm not saying you did non sense. Just...as in all physics publication, we discuss each other point...to go further ahead and improve.
Perhaps check "cells fire" on this forum...it can be nasty.
Ohthetrees build, this is, to my point of view...a good solution, it's a parallel build..but the flexible connections are good.