to be fair it’s still better than most Chinese batteries you could get
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My second ever battery build. This pack is for my backpack.
20s2p P42a
.2mm x 10mm Ni
3D printed ABS support
Clear heat shrink
.03" fiber board
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What was the rationale for using small cut strips rather than a big nickel tab? Not an expert but nothing else jumping out as weird, nice tidy balance cables, some of the welds might be too close to the centre of the negative terminal but it’s through another piece of nickel from what’s visible so who knows if that’s a problem. Is the 0.03" fibre board referring to the separator in the spine?
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I could not find 2P precuts or decent source material to make my own. If you have a link I would appreciate it.
Tell me about spot welding close to the center of the negative terminal. This is not something I’ve heard mentioned and exactly why I’m posting. What’s the potential fall out? What distance would you say is too close to center?
Yes, the fiber board is just thicker fish paper. Nothing’s going to poke through it and it adds some rigidity. Over the tabs and large solders.
the internals of the cell are a bunch of negative and positive plates in concentric cylinders “a spiral roll of a “sandwich” of the two electrodes with a plastic sheet between them”. the bottom edge of negative is attached to the bottom center of the can. So welding in the center is avoided to avoid messing with that internal attachment.
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It’s actually a spiral roll of a “sandwich” of the two electrodes with a plastic sheet between them.
Each electrode has a metal tab connected to it, one tab spot-welded to the underside top contact and the other, as you mentioned, spot-welded to the inside bottom of the metal can.
@izzymonster, a 3mm circle in the center of the bottom is where at least one major battery manufacturer says to avoid when spot-welding.
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thanks for the correction. 
note to self: stop relying on cunningham’s law.
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What do y’all use to round the corners on your nickel? I usually do it by hand with some shears but I know there is a tool some of y’all use to just remove the corner.
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There are some expensive corner chompers on eBay that are like 50 bucks (I don’t use em, don’t have the link) but I’ve just gotten good at cutting them with shears.
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At this point I just spend too much time cutting corners to where I just wanna get some of them corner chompers
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Magnet go jump
Where do y’all get your nickel? I’m looking to get 30-50mm wide and .15 or .2mm thick. Gonna be buying in bulk more or less so I’m looking for a source that isn’t “by the foot”
https://www.amazon.com/gp/aw/d/B08HN9M9YQ?psc=1&ref=ppx_pop_mob_b_asin_title
There are probably better sources but this passed the rust test and worked well
Looks like some people got nickel plated steel in the reviews now so maybe not a good source anymore.
This worked ok for me & I guess you can sharpen/replace the cutting tool
https://a.aliexpress.com/_mLQLHIY
And ooh this 2-in-1 could conceivably make slots in the nickel (?)
https://a.aliexpress.com/_mrHloDa
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Hi there! I’m hoping this is the right place to ask. I put together a 10s4p battery for my front hub e-bike and had a question about connecting the main wires. Is it okay to first solder the main wire to a piece of nickel strip and then spot weld this strip with the wire to the battery? I want to avoid soldering directly onto the battery to prevent any heat damage to the cell.
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Assuming all else is done well that is a great way to avoid soldering directly to a cell.
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There were reasonable back in the day.
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Where did you locate this battery pack I like that it looks very simplistic
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