1st pic looks great but the second pic, the discolored circle is big and scary. Maybe Iām zooming in too much. 
if youāre getting a range between these photos youāre probably good
Some things that have worked for me to get it to stick better ā maybe you can lower your power a bit.
Clean the cell and nickel with alcohol.
Lighten up the pressure on the probes.
Oh and you can reshape the tips with sandpaper.
My first full (practice) go at a 5P groupā¦
Iām planning on cutting the barley paper a little bit wider and longer to wrap around fully next time, partly because I donāt know if I trust kapton tape to insulate between the edge of the cell and the balance lead. Iāll also be spot welding a couple more shots on each.
Is there anything else I could improve on?
How you plan to connect the p packs later?
Since iām getting 35A cells (VTC5A), I plan to solder 2x 10AWG wires to the nickel strips to connect each P group.
If you split the solder point on different cells than that should work out with only one layer of nickel. If no, than better add some layers.
Not really sure. Only running 80a Motor Max and 30a Batt Max per vesc. Itās a 30q 10s5p pack so I donāt think power is the issue. That braided copper can flex and lead to fraying is all I know. The battery is attached to the deck with no flex.
Well then I might guess mechanical stress from vibration combined with the braid going from stiff soldered area to flexible over a short distance.
Even though the pack is velcroed to the board, the left and right side of the pack could still vibrate up and down up to 1mm each side. Eventually braking the braid.
If that is true, a longer section of braid between the two soldered areas would allow for more flex and less stress on the braid.
Exactly this or even two strands of 10 gauge silicone wire. Thatās what we used.
10awg is probably overkill, for a 5p I think 2 bits of 12-14awg would be enough.
Better over than under in this case. Less room for bullshit later. 
Was that link braid pre tined or plain cooper.
I suspect the solder flowed to close to were it was flexing and stiffening it all up and putting the flex in one very small. space as it flexed repeatedly in this small area it started braking the strands. Increasing resistance increasing heat and work hardening the copper. This ends up been a self perpetual cycle that escalated untill catistrofick fault you end up with there. This is what I think most likely happened from working on large factry mechinary that vibrates and seen similar results with stranded copper.
I think your better of with the copper braid over the silicon wire just make sure thereās more space between the stiff soldered area. (I prefer the pre tinned stuff personally as I fined it easya and quicker to get the solder contained were I want it for a better more controlled concetion)
Disclaimer this is my opinion Iām sure otheres will have different or contradiction ones i recommend reading them all and making your own mined up to what you think is best.
Just finished my 12S4P for my new project.
I ordered the 30Q with the Tags from nkon.nl every row of my holder has 8 batteries and there is a total of 6 rows (8x6 = 48 cells = 12s4p). I connected 4 of them in parallel and then connected to the next pair of 4. So it means each row has 2 parallel pairs. For connecting the parallel pairs I used a thicker wire because the tag only would not have a desirable amp rating by itself.
So I just soldered the parallel pairs together with the tags. If you have a soldering iron that can get hot enough and you sand the tags a bit then it will hold up quite well.
Just donāt want to invest in a spotwelder that I only use once every 2 years.
The case and everything is printed on my 3D Printer (Material PLA)
To improve shock absorption the cells have acrylic and hotglue between the cells.
What about fish paper? š¤·
With sturdy spacers, imo not needed. But if the spacers are prone to cracking bending or meltingā¦ I still say not needed, and get better spacers.
Mechanical stress is a real thing that can be a strong factor to this; Iāve had big issues with it on my packs as well:
btw you can get neutral cure silicon amazon prime!
https://www.amazon.co.uk/gp/product/B005X685NK/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
Hereās some pictures of my latest battery build-
Is there a reason why you out the fishpaper everywhere but not between the p-packs?
