The battery builders club

How-Tos & Esk8 mechanics
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#19833

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what about these? They look a little hot, but they were the ones that stuck the best.

2 Likes
#19834

Much much much better!

#19835

An offering for judgment

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1 Like
#19836

Looking good!

1 Like
#19837

I did a bunch of pull tests on a spare cell, I wasn’t able to get any metal left behind after a pull unless I did 2 hits of 2 pulse at 99A (so 4 pulses per weld)

Is my spot welder really this shitty? I verified that the nickel strips were pure. It should be lower settings right? SUNKO 737G using 0.8mm strips (because it’ll be a 180A pack and I don’t want bottlenecks)

#19838

listen I am new to this also, but I think that the overhang of the nickel on the sides of the cells might be an issue with shorting the p group next to it ( depending on your configuration)

4 Likes
#19839

0.8mm thick nickel strips?!

No wonder your welder can’t handle that.

0.8mm is WAY overkill, and also 100% the reason you’re having trouble.

Don’t do that. 0.2mm or even 0.15mm is more than enough to “avoid bottlenecks” on a 4p pack.

I rescind my previous judgement, it may look good, but it is not good.

No, just way underpowered to weld nickel anywhere near that thick.

4 Likes
#19840

Thanks for catching that. I’ll be trimming it down and making it less sharp for sure.

@MysticalDork I’m getting a good pull test with my current settings, should I tear off all this nickel and use 0.2mm or would it be okay to leave the packs I’ve already done?

#19841

I personally wouldn’t call a pull test “good” unless it’s tearing the nickel, but if you’re satisfied with the strength, and this is a pack solely for your use, then that’s a judgement call for you to make.

#19842

yes, it’s solely for my personal board (unless the board is still good down the line and I happen to sell)

the pull test tore holes in the nickel but didn’t tear the strip like a classic paper tear.

1 Like
#19843

is extending BMS balance wires okay? my harness wires are too short for my config.

#19844

image

4 Likes
#19845

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Any tips on making this part easier? First time making series connections this way.

#19846

Heres a vid @Skyart made a while ago

4 Likes
#19847

doesn’t really help me at all, I’m already doing all of that. the hard part is getting a nice bend and knowing the exact angle to have the wires soldered at. basically everything after the video ends.

#19848

But you’re not.

Do you see a difference in the following?

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Screenshot_2022-02-20-17-58-29-21_965bbf4d18d205f782c6b8409c5773a4

2 Likes
#19849

yeah those bends are nicer.

#19850

Focus on the solder pools. Yours look a bit cold and small to me. I would reflow those before you move on to things not shown in the video above.

3 Likes
#19851

they look cold because the wire had some silver solder left in it that mixed with the good solder I’ve started using recently. I’m using a TS100 at 400F with 63/37 solder and some tip tinner.

that video does remind me to add some bands of tape for structure before I start adding more series connections.

I won’t be moving on with series connections for now. gonna get some fresh wire and wait for more tips. The goal is to finally bang this battery out by the end of the long weekend.

#19852

Your wires, pre-bend them before adding solder to the tips.

So if your wires are 4cm long, cut them, and then forcibly bend it to a nice U shape, then cut the silicone off the ends and tin them.

2 Likes