Add a plastic strip here, it’s very easy to short the pack otherwise. Only fishpaper would make me nervous. Only personal preference though.
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Any recommendations of what type? Do you mean across the whole pack like the line you drew as I want the pack to be able to flex a little.
The nickel does not go all the way to the sides of the battery groups. About 5mm from each side
Thanks
What you have available, the type is not that critical. Non-conductive ofc. You can cut the plastic separator into a piece for each p-group pair, that way you retain flexibility.
Ik, I build mine the same. It’s still very easy to short the pack there, f.e. if a screw gets dropped. You don’t have to do it though, as I said, it’s my personal preference.
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Ahh, ok. I’ll have a look in the shed tomorrow. Will have something surely 
.
I did think of 3d printing a spacer for the middle section but couldn’t really find a suitable model on thingiverse
What about the other direction between the packs, would fishpaper be OK there or some foam / padding. With there being a bit of flex I thought something soft would be best as a cushion between them?
Is it also ok to shrink-wrap it in the 6 sections separately?
That’s not needed, because after the series connection the two sides are on the same voltage potential.
I’d advise that, yeah. You can also carefully cut the shrink wrap after you shrunk it, that way you have more coverage.
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Thanks @Linesflag for clearing that up for me. Thiught friction from the flex may put stress on the nickel
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There should be no flex or stress in the nickel tabs when you make the series connections from silicone wire or tinned copper braid.
If you’re unsure how to go from here I suggest you look up RBEMotion on youtube (@ShutterShock; it’s linked on his profile), he has a good tutorial on flex packs.
For future builds, I suggest you put down solder pools on the tabs before you weld them, or even solder the series connections entirely before you weld the tabs. That way you prevent more heat from entering the cells.
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Already a subscriber of @ShutterShock and following through his video (although was in the moment spot welding away and only realised after I had done them all and not left the final ± tabs off)
This is where my question came from though. He used no spacers or foam between any cells.
You have suggested only down the middle as it’s not needed side to side
@Skyart makes some amazing batteries and has it both ways on his website and battery build log see below hence me asking what is best before continuing
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Awesome haha
Ya it’s not necessary really, imo.
I haven’t seen Art do it either but I probably just missed it.
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Probably can take only one battery pack with me on my big move. So going to build new packs this summer.
Therefore calling all EU guys, where to source legit p42a cells in Europe (besides nkon)?
I think I remember @klaus79856 had a big order from the factory coming, but didn’t hear much about it in the last time. Any updates are appropriated 
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I like putting foam in those gaps. Its only something i’ve started doing fairly recently, but it helps the packs flex so much better.
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nkon is the way. (wesellcells.eu is also okay)
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Not so easy to catch the right moment when nkon has them in stock thou 
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yeah, you gotta be fast 
right now there are some. shipping is in may though.
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And their customer service was fucking awful. But all recent signs point to them having gotten their shit together.
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Half done with copper sandwich welding a 12S4P Samsung 30Q pack for myself, thought I’d share my results
Done with .1mm copper sheet, .1mm nickel plated steel, kWeld at 50 joules per weld.
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Have you done a pull test to check the quality of them welds?
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Yes, on a spare 30Q from the same batch. The copper ripped to shreds without letting go. Its solid!
I was extra careful with the mats: cleaned with 98iso before welds, cut all exposed corners, sharpening weld probes every 30 welds or so.
I tested a bunch of welds on a razor as well, and the 3 pieces became 1. I know its not the same as the battery, but the results look exactly the same. You can see the copper between weld spots discolored from the heat generated. I’ll get more pics of other p groups so that you all can see its uniform.
I actually got similar results at 45 joules, but went big just to be sure.
Its the right tape… for drywall!
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