Yeah tbh i have no experience with those cells, but from most reports i can remember they seem to be pretty robust.
Before opening and inspecting, i would definitely recommend running the battery safely for a few cycles and observing the behaviour.
Start from a full voltage balanced pack, drain it a decent amount, rinse/repeat
The ones in the cyboard are from a really long time ago when this cell was brand new on the market and was being sold for $2.50 a cell brand new.
Very different than ones being sold now
To add onto that, they didn’t discharge down that low due to severe loading either, so it’s not like they sagged lower.
I too think they will be fine, good thing you caught it when you did though
Alright, so I’m getting towards the end of planning my build and I’ve decided I want to learn to build my own battery. I’ve acquired most of the materials and now I’m just planning the actual layout and construction. I’m using this deck and the verreal f1 enclosure. I’m planning on making a 10s3p double stack 18650 pack. It will need to be offset stack to fit without a huge gasket. I know welding nickel strips for series connections seems to be very frowned upon, but does that apply to something like this as well? Between the deck and enclosure, there will be no flex.
If I don’t just weld nickel strips for the series connections, what would be the best way to layout the pack in your opinion? Should I do flat 3x1 groups and have series connections on both sides of the battery? That seems like it might make it too thick as it will be harder to get them to stack . Otherwise, it seems like no matter what I do some series connections will have to go from one side of the pack to the other since I’d want to put tabs on whichever layer has 2 cells for that group. Are there any issues with that if I make sure to properly wrap everything up? I’m not sure what the best way to go about this is, but I’d like to do it as right as possible.
Anyway, I’ve been leaning towards just welding the series connections, but if you guys think it’s a bad idea even in this case with very little flex I’ll try to find a way to avoid it.
If you don’t have enough space for wires you can use tinned copper braid for the series connections. Nickel is a shitty conductor, thanks why it’s great for spot welding and bad for actual conduction. So a series connection made from nickel will get hot if you draw too much current from you pack. I would strong advise against doing so and instead refer tou to the many pictures in this thread on how to build series connections.
I’ve got .2x30 mm nickel and the pack will only be run at 30 A for now and only 60 A at most ever. From Conductor Current Ratings [SRO] that should be fine as far as current capability. I don’t know that copper braid really helps the issues with the layout of the pack over wires. I was thinking I’d do triangular 3 cell groups to make the offset double stack, but routing series connections becomes slightly strange with that layout unless they’re connected just at the ends. If you have any examples of packs with a layout like that I’d love to see them, but I’ve yet to find any after some searching. Most things I find are very large flexible packs or bricks for on top of the board. My forum searching skills could just be failing me though.
I think you will be fine, but a sketch on what you’re trying to do would be very helpful to show where you’re getting at.
The red is just to show the p-groups, the yellow would be the nickel. It’s an awful drawing, but I think it gets the point across. I’d have 5 of these groups per side with the pack being 2 wide. The top-down would be something like this:
With the bottom layer having 16 cells total between both sides and the top layer having 14.
I actually just started going through this thread from the beginning and saw a few examples of people soldering copper braid to the strips at the ends of the cells without a tab. Is there a good way to do that? I’m not sure how to weld if that is already there and obviously you don’t want to solder with the nickel already welded to the cells.
Edit: Also the sides won’t be touching in the middle. I’ll have a divider and fish paper in there.
Alright yeah you should be fine in this configuration. You can wait for other peoples input though if you want. If you don’t exceed 80 Battery amps you’re golden. Just a sidenote, a 10s3p made of 18650 won’t give you much range, and also will sag a lot under draw. 21700 cells would be better, f.e. Molicells P42A.
Due to the size of the enclosure 21700s just seemed like a bad choice, though my choice to try to squeeze a double stack in there may not have been the best. I think they actually do single stack 18650s in their prebuilt with this enclosure, but it’s ~33 mm deep so I thought I could fit an offset double stack 18650 pack in there. I need to make a gasket anyway to match up the flat enclosure to a slightly concave board. Anyway, double stack 18650s seemed like a better route than single stack 21700s and now I’ve kind of committed to that for better or worse. Range shouldn’t be a big issue though. I’ll be fine with 10 miles and I think this should give 10-15 miles. I’ll be using urethane wheels and a single belt drive.
Yeah sorry totally forgot about the enclosure part as I’m used to making my own enclosures. Under your circumstances this seems like the best option.
You can buy that same jig on aliexpress, found it some time ago 
Think its the store selling welding pens
(cathing up with the thread a bit haha)
what would be the best way to wire this,
I have:
10s 4p P42a
110 inches of 10mm x 0.2 mm nickel
about 70 inches of 10awg wire
a lot of fish paper and captain tape.
and hopefully enough solder.
and I plan on putting a loop key in somewhere.
I plan on building the battery tomorrow
thanks again for everyone help
Looks like you have enough width space. Build the pack something like this. Have the nickel fold up and use braided cable or silicone wire as series connections.
In this type of configuration, do you use any kind of insulation between consecutive P packs (i.e P1 to P2) or are the nickel strips touching?
I imagine there is no issue with them touching but would flexing (connecting/disconnecting) continuously cause any trouble?
They are touching yes, and it’s no problem, because the series connection is connecting the two touching points, so its negligible.
the only thing is I don’t have nickel tabs like those I only have
0.2x10mm nickel can’t transfer a whole lot of current. You should consider getting 0.2x30 and folding it over.
Its too late for that, mabye next time.
