Well, lots of smart guys here, congratulations. Immagine that that battery was assembled and...sell to a friend. Lot of people think "I have a spot welder, I'm going into business" without having the necessary knowledge to do that kind of stuff. Knowing that A stands for Ampere and V vor Volt isn't enough to put friend's butt to risk
This is the battery with the positive and negative end soldered, they're clearly soldered on the single nickel strip bended behind the plastic support, for a "neat setup"...
: you are right, current flow isn't equally distributed through the cells, so lifetime is questionable. And you are right again, the negative end it's a candidate for "Santa Klaus glowing star" battery reality show.
: probably some cinese spot welder was used, and while they (somewhat) work, you don't have a lot of control on what you're doing. Very "fine" observation -wasn't intended to be remarked, but the more the better
: Maybe you mean the "standard" gasket used under the PVC protection layer of the cell. Over-the-top adhesive gaskets (like this https://eu.nkon.nl/accessories/welding- ... 18650.html
have a cost (in money) so probably that friend doesn't deserve them, or the "assembler" isn't aware of their existence... And you're right about the positive end (same for the negative) with only one strip, shrinking those 40A in 0,15-0,3mm nickel strip mean looking for troubles.
By the way, that battery was providing energy to...TWO MOTORS, with peak requests around 80A. I've finished to read that post, and the more I've read the more I've wonder how "innocent" some people are. (I think it's something called "the Dunning-Kruger effect")...
And least but not last, that post began with the client publicly thanking the assembler...