The nickel is 12mm x 0.15mm so I thought that would be ample for the size of the pack? 1 strip should be good for 40A or am I way off?
Batteries looking good, Nickel should be enoughā¦ I bought some 15mm wide 0.2mm thick nickel.
Yet to put my DIY welder together.
I will be using one of these butane soldering irons
Yes this is acceptable.
I hope you dont plan on using that for battery welding. In my experience, they donāt get hot enough for that application. You have to leave it on the battery for too long. But thatās just my personal opinion on it.
Iāve got a butane soldering iron, not this model though. I donāt find it anywhere near hot enough for this though. I use the exhaust outlet for heat shrink!
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Sorry, I meant bottleneck in the abstract technical sense, as in the copper braid is likely many times less resistance than the nickel. I think in real life, youāre likely fine.
But in the technical sense, 12mm x 0.15mm nickel strip is good for about 8.5a, and gets warm at about 13 amps, quickly getting hot hot hot above that.
https://endless-sphere.com/forums/viewtopic.php?t=68005
That table on the first post looks very conservative, but several people have run experiments and verified. Thereās some assumptions about total length of nickel strip for the whole pack, that Iām ignoring to keep it short. 
I got the 8.5a and 13a, by taking the Pure Nickel 7mm x .3mm line, which has good at 10a and acceptable at 15a. cross sectional area is 7x.3=2.1mm^2.
For good,10a/2.1mm^2 = 4.76a/mm^2. For acceptable, 15a/2.1mm^2 = 7.14a/mm^2.
Your strip,12mm x 0.15mm is 1.8mm^2. Good is 4.76 x 1.8 = 8.57a. Acceptable is 7.14 x 1.8 = 12.85a.
If youāre using 1 strip per cell for series connections, for 30q, youāre actually pretty close to the manufacturer spec of 15a continuous.
On a side note, I love this thread, thanks @SimosMCmuffin
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Interesting stuff, so would it be fair to say that 40 amps on one of these strips would be like a fuse?! These are 20700 cells.
Oh oops. From what Iāve read, which unfortunately is a LOT, brief bursts should be okay. Like maybe 1 second bursts. More than that, things will be getting pretty hot, so youāll go through a lot of heat/cool cycles. Most setups donāt really pull huge amps for more than a second or two.
But Iāve also read about people like @Deckoz running really tiny strips for huge packs, showing telemetry for huge amps, and no ill effects.
Since your pack is already built, maybe get one of those $5 thermocouple probe things, and see how hot the nickel actually gets. Something like this. https://www.ebay.com/itm/TM-902C-LCD-K-Type-Thermometer-Meter-Single-Input-Thermocouple-Probe-Da/153231302597?hash=item23ad4c1fc5:g:QOUAAOSwcWpbfmul:rk:29:pf:0
EDIT I donāt think theyāll burn off like a fuse!
I was comparing it to how a space cell was built with 1 strip per cell in the series connections and those strips are 8mm x 0.1mm?
current space cell 10s4p 30q is a 60a pack with 60a fuse and xt60? R2 is also set up with 30 battery amps per focbox. So 15a/cell.
I know I read the specs on nickel for the current raptorās 10s4p packs, but canāt remember the detailsā¦ I think it was more than 8x.1 though.
Very few eskate packs meet the standards in that ES table. Based on math and physics I believe those strips get hot (itās hard to measure this with the pack being sealed into the enclosure) but based on chatter in this forum I think the packs hold up for the most part.
I did a few A123 builds which are 1 or 2 parallel cells with huge amps. I stare at my spot welder and piles of nickel strip, and scratch my head. Then I end up putting copper in all series connections.
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Almost there.
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Iād say hats off to you for:
-isolating P groups -not crossing balance wires -labeling your series contacts
I would use shrink wrap instead of entirely kapton tape. Definitely use tape to tie down the balance wires, but youād be much better off using a thick heat shrink over the entire pack.
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Here you go.
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Job Done you made it look easy 
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I have a single 0.15mm nickel strip on my new pack in MOST places on the pack. My new BMS has two temp sensors that I placed as close to the nickel strips a possible in places I thought would see the most current.
During my testing, the nickel strips havenāt even heated up more than a degree or two past ambient temperature. I think itās fine in almost all cases(based on my testing so far). I also do not have any braided wire or anything else on the series connections.
I always suggest people double or tripple up if possible though, because everyoneās riding style is different. I mean, for all i know the person making the pack is going to compete in the uphill race and dump their entire packs capacity in 5 minutes.
EDIT: Battery inf: 10s5p 30Q, dual foc boxās set to 40A each for 80A total. Ivāe done a few runs at 50A each box and it yielded similar results.
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What type of glue do you guys use to glue your packs. Iām looking into building my first li-ion pack and will be using cell level fusing as I donāt have a spot welder. I heard silicone works, but is there a certain type I need?
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Iāve only built a lot of shitty packs with recycled cells. I use standard hot glue personally but if I were building a new pack from scratch, Iād use E6000. Curious what others use as well.
The correct answer is natural cure silicon type 2+. Most everyone uses hot glue though.
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Neutral cure? Something about acids and solvents not present?