Can’t see inside of the wrap/kapton but the balance routing looks good. From what I can see, looks like a solid first effort. Assuming this guy is an antispark?
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looks more like a fuse to me.
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Outside looks good, do you have pictures of the build process? Otherwise it’s hard to say anything.
A large coil of nichrome wire in a bucket of water. Calculate the resistance to achieve the maximum rated current.
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Hi All. Sorry for interrupting this thread. Hope here it is right place for my question. Iam just received Nkon batteries with clear wrap. But what surprised me is that this cells have on positive pol just fish paper ring below clear wrap. I saw till now plastic one.I need build 3 packs for top mount on mountain boards. So if I will stick on it next fish paper ring, it will be ok? Slightly doubt , how safe it is .Thanx all for any comments.
Those FETs say they’ll do 70A continuous each, with case temp at 100C. Maybe I’m missing something thermally (that the aluminium block heat soaks really quickly and then can’t dissipate it) but from the datasheets it seems fine for a lot more than 20A? I can’t quite read the part numbers on all of the fets to confirm if they’re all the same and ganged up in parallel, maybe they’re laid out in a way that severely limits it like one series FET needing to take the full battery current, but still it seems reasonable
@ApproachCautiously I think you should put down strips of fish paper between the overlapping balance wires, that’s the standard method like these from Al. The little rafts keep them safe from eachother
Quick Google gives a range of operating temps for hot glue, the lowest range still seeming to be safe for ~80C. Hopefully the outside of your cells stay within that 
. And yeah I use electronics safe silicone from RS or dowsil, I think my pack with it is only 12-18 months old but so far it has held up nicely, no drying out
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put it in the books, i’ll visit ya again within the next 4 years!
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That would require me to have fish paper which I did not have when fixing it. 
I’m not planning to sell the pack any time soon, and if I ever do I’ll make sure the use of hot glue is known. If it could survive in that original state for 5 years I’m sure it’ll be fine for longer with the hot glue
If I was rebuilding it fully or just building a new pack I wouldn’t let it look like that to begin with. I’d do it the right way to begin with. Although the pic of it to start with 100% belongs in that other thread as a bad example. 
How they didn’t end up shorted to the battery terminals when shoved between them is a mystery.
Most of the silicone available at the hardware store already is electronic safe. Personally, I picked up some that was clear but that was to make it easier to remove if I wanted to fully enclose anything in it, but the stuff I have is too flexible for that use anyway. Luckily it works super well for creating more of a seal on my enclosure as even after it is cured it is slightly tacky. I didn’t want to waste a full tube of my gasket making silicone when I do have future plans that would require removing the gasket.
Not here it’s not anyway, I really had to go out of my way to find neutral cure stuff. The vast majority is acetoxy cure
As far as I’m aware I bought a neutral version although of course it isn’t listed on the product itself. It very much smells like one and the tube lists the vapor as flammable which is on par for neutral cure.
Then again the tube does list itself as being tack free in 30 minutes which isn’t even accurate, so I really shouldn’t be surprised it doesn’t list the cure type. the stickiness it keeps works well for my uses at least.
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Roof and gutter silicone is neutral cure. And its cheap.
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Yes, that’s fine.
On many types of cells, the plastic ring isn’t held on by anything but the wrap, so when the wrap gets replaced, the ring falls off and they replace it with fishpaper.
Fishpaper is actually a better material than the plastic in terms of heat and abrasion resistance, so it’s fine.
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makerx antispark switch
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next item on the list is a 12s 8p 30q pack, is it a viable option to just put a big sheet of nickel on top of the P group and fold it over the sides? I made my calculations and it checks out, altho im not sure how to weld to the positive sides of the groups considering the big nickel sheet is going to cover up everything visually. I dont want to weld to the negative side of the cells by mistake, even when the fishpaper rings are there it seems scary, any ideas? layout is going to be 2 rows of 4 cells stacked (times twelve for the series connections)
0.2mm nickel, 7.2cm wide, can handle around 130A (8P can output 120A) how many S connection cables should i connect? should i spread it out over the available and use 4? maybe 3? not sure how to calculate this. My concern is if i dont spread out the points of load it might create hot-spots on the nickel.
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unfortunately i dont, altho everything passed the pull test,BMS works perfectly, my biggest concern is the XT90 which has 4 15awg crammed into it, i will have to test that part heat-wise.
I just googled the part number and lots of 20A BMS came up. The part number itself seems to indicate that too. Maybe there is something else thats current limiting apart from the FETs.
Maybe that is for charging purposes where it can handle more than 20A somehow? 
Honestly, I don’t think I’ll even be pulling 20A anytime soon seeing as I’m used to the performance of an ESC which is likely not even pulling that much current from the battery. Only real reason I’d use significantly more current than the ESC did is if the change from hub motors to a belted setup requires way more power.
Also I didn’t realize this bit of your reply was related to my battery oops. It is already in two layers of heat shrink wrap so I can’t get a better photo of anything because I don’t want to redo it.
Don’t worry about that connector. They’re very robust. As long as your soldering is good the connector will hold up.
Yes, it’s totally viable. I’d suggest double insulating the shoulder on the pos side of your groups where the nickel folds over as below. Just score the fish (cut to appropriate length and approx 3mm wide) down the middle for a clean fold.
Tack you nickel on the pos side with a few welds and push the nickel down to show you the pos terminals. Search this thread and you’ll find examples of how various people do this. Personally, I use the handle of my wire cutters which is a dense foam rubber.
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