Spot welding Copper / Copper Nickel / Copper Stainless Steel Sandwich

[Vanarian]

Quick thoughts from when I was trying some shit with copper and nickel…

Have you planned eventually to simply spot weld nickel strip to copper strip itself without spot welding it to the cell?

Plating nickel on top of copper does not work for high vibrations environment because it makes the strips brittle (corrosion happens at copper level). I exploded a jar while trying that so it’s also dangerous no joke. You don’t want an acidic bomb anywhere near your skin.

So spot welding the copper and nickel together (excluding the cell itself) may bring few advantages :

• you can choose how much nickel should be covered by the copper. If you can’t easily solder all the strips, just have tips of few mm of thick nickel (you spot weld that to cell) + all rest of the strip is fully copper backed (cools down the nickel + drives up the ampacity anyway)

• you can also just make raw strips or tabs of nickel soldered copper for non soldering batteries systems around

• if you can do accurate metal cuts, do a comb design soldering copper / nickel at the tip to further reduce the nickel path and again, just solder the nickel to cell?

This is a lot of ideas but for DIY level machines, it seems more accessible IMHO

Cheer up for your success

Edit : the power your welder has is already crazy though, I should come out of my rock more often

[SternWake]

@Vanarian

Have you planned eventually to simply spot weld nickel strip to copper strip itself without spot welding it to the cell?

I am not sure what you mean.

My experiments tonight have me contemplating not using any nickel or nickel plated steel strip at all on my next battery build.

0.25mm of copper welded strongly to the cell with no nickel or nickel plated steel on top, at 85% of the available power of my welder.

The copper to copperflux/ brazing paste seems to eliminate the need to use nickel or nickel plated steel atop the copper to achieve a solid weld.

Ill solder dual or triple silicone jacketed 14 awg wire between parallel groups as series connections. My battery needs to flex.

[Vanarian]

Well that’s an advancement! Nice to hear, makes my old tests way outdated.

So full on copper + flex cables is incredible.

Are you able to test if the copperflux/brazing paste and copper welding hold strong enough against impacts/vibrations?

[SternWake]

I am only able to judge weld strength by removing the welded copper strips.

Once a good weld.is achieved the copper tears around the weld when pulling on the strip. So the copper itself fails, not the weld.

0.2 copper tore pretty easily compared to 0.2 with 0.1 nickel.plated steel sandwich.
0.25mm.of.copper alone, well, 0.1and 0.15 stacked, no Nickel, felt subjectively stron enough.

Impact and vibration wise, I dont know.

[glyphiks]

There is definitely substance to the concerns around the copper holding up in our battery construction.

Even with nickel welded batteries, I still felt like it was super important to restrict any stress to the welds as best as possible, and i think this is even more important with copper.

I think that as long as we are securing our tabs down to the cells as strongly as possible, that’s the best we can do in terms of vibration perspective, impact is a different story but I feel impact damage is quite a lot less common as well.

[Dinnye]

My 0.3 copper 0.1 steel sandwich welds on the glitter 811h at 65% are so strong I teared the cell housing instead of the copper strip. 0.2 nickel feels significantly flimsier by comparison, it took a lot of force to roll off this weld with needle nose pliers. That was a P42A which has a relatively thick can

[Dinnye]

Here an 18S6P pack that I built with 0.3 copper. BAK 45D cells. It’s performing incredibly well in a raceboard

[glyphiks]

You can see the thickness of the can in the photo

Makes me wonder if the weld weakened the can?

[Dinnye]

Judging by the amount of force it took to open it up, it probably didn’t. It was super hard to roll off the copper. Didn’t suprise me that the can was torn, since I was barely able to roll it off. It’s multiples of 0.2 nickel + kweld weld in strength

[Pecos]

Do you think with some settings tuning, the awithz p30c welder could be set to constantly at not full power weld .2 copper without the flux? From the msds and watching some of those videos of yours as well as @SternWake ’s experimentation im going to try a couple of different options and see what they do to get good results to stress test as well as how the process of building a high discharge/low p count pack. Im thinking of something crazy . A small light build that can also perform like some of the larger builds has me gathering supplies but hesitant about construction methods still so im taking baby steps. The ability to make an2p or 3p pack that is capable of 200-300 battery amps is going to demand copper busing

The tear off looks great on that video and i want to now also take the process to completion with soldering the flexible connections in a flat pack. If the flux paste is necessary or not or if it can be used to make the connection more reliable as well as how much and how to apply consistently

By the way, those rs50 cells have me waffling between them and the 50pl. That price point is absolutely amazing with their performance testing you and mooch have been doing and such a strong performer for around $6 a cell is crazy. Got my hands on some of the bak 45d cells to play with while i wait for your stock of the rs50s to drop to get my technique dialed

[hummieee]

My attempts welding copper failed but found they make hybrid copper/nickel strip and very easy to weld and not too expensive.

[Pecos]

There is nickel plated copper at the diy500amp.com store, might be if 25-30mm strips can be sourced a good simple solution.

The solder ability and welding ability of nickel plated copper might be the cleanest solution. Gonna get some and test

[SternWake]

Without the flux, at gear 690, I blew a hole through the 0.2mm copper into the can puncturing it.

I guess it is possible I had an airgap with that raised ridge on the cell can, and or the dented cell can.
That was my last attempt without flux, and the next cell, with flux, same settings produced two even solid welds.

I was not impressed by the strength of 0.2 copper. The welds stayed put, but the copper tore from around the welds pretty easily.

I have no 0.2mm pure nickel, only 0.15., but have not tried it on its own with this welder.

Peeling off 0.1 copper, 0.1nickel plated steel sandwichtakes significantly more force than the 0.2 fluxed copper.

But I dont know if this means anything in a completed pack when p grouos are glued together and the folded over the shoukder tab for flexible series connections is also immobilized.

Just 0.25mm( stacked 0.1 and 0.15) copper was a noticeable increase in peel strength.

And the 0.30 copper, well 0.15mm double stack, especially the fatter weld, on left had as good or better peel off strength as 0.1 copper, 0.1 nickel.plated steel sandwich.

So I think one should Aim for no less than 0.25mm or thicker copper just for the strength factor, and happily accept even higher ampacity.

I was likely using far more flux than required. I think application with a small flexible squeegee is my next plan.

I want to get even better Macro photos.

One other thought is that I basically started off with new pointier electrodes.
the worn fatter ones with a wider diameter would make for fatter welds, which are harder to tear, but alao likely take more power.

I’m gonna experiment more in a little bit.

[Pecos]

@SternWake

was not impressed by the strength of 0.2 copper. The welds stayed put, but the copper tore from around the welds pretty easily.

I think part of the issue might be oxygen, copper will absorb lots of oxygen when welding and become weaker and porous as well as losing a lot of its ductility. The flux could be creating a shield or sink for the weld and may end up being absolutely necessary. It may also be that the “organic “ component in the flux is carbon which is used in casting copper to absorb oxygen and prevent the copper and copper alloys from taking in too much o2.

Need to experiment a little. Alloys and also flux agents as well as coated copper (nickel plated) could help a lot here. When i was casting copper i would do much of it under water or shield it with argon to prevent the o2 from fowling the cast

[SternWake]

In Nelvick’s videos he says that both Glitter and AwithZ say flux is necessary for anything over 0.2 copper, and that one can weld thicker without, but that consistency suffers.

I find that the flux effectively tinning the copper strip in between the welds and a few Mm away to be interesting.
I wonder if this tinning is also between copper and nickel and actually increases the resistance of the weld.

But when I used 0.2mm copper 0.1 nps sandwich at gear 990 with no flux, then gear 790 with flux, the fluxed welds were wider, and i don’t think the marginally wider electrode tips played a part.

[Pecos]

There is also tinning solder flux used by plumbers. I use it when soldering angle stops to help lower the heat soak required to solder them in and it will quickly tin the copper so i don’t over heat the valve’s plastic components killing them. The flux is very aggressive and acidic though and needs to be cleaned off very well in order to not corrode the copper or joint.

Seems like the product nelvick has sourced is similar but using a less aggressive acid or acid free flux for electronics. Gonna make a list and start writing stuff down so it counts as science

[hummieee]

@Pecos

The solder ability and welding ability of nickel plated copper might be the cleanest solution. Gonna get some and test

Plating is super thin and not going to add almost any of the needed resistance to weld.

[Pecos]

Exactly, i suspect that it isn’t adding resistance as much as it is shielding the weld point, preventing o2 from getting incorporated into the weld preventing the copper from then becoming vaporized and combusting as well as reducing the fowling. Ive got some argon ill try shielding with raw copper but its gonna take a little experimenting to isolate the core issue.

I don’t think using argon, even if it is effective, is a good solution though. Would really complicate the process. But it would be a good data point for solving the copper welding issues

[SternWake]

Searching ‘copper brazing paste’ should yield more info me thinks.

Calling it ‘Flux’ could be technically inaccurate.

Maybe we should refer to it as Floouxx, like how Nelvick sometimes pronounces it

When I welded dual stacked 0.15mm copper with flooux, at 99% power and triple pulse, the tiny fan in the 9vdc 15amp power supply ran for a lot longer, than it did at 85% power for 0.25mm, after the weld.

I wish i had an exhaust shroud for my bedroom welding station, as there is fair amount of Flooux smoke right after the weld. No sparks though.

[Pecos]

If you can’t find an easy solution for ventilation, please consider a box fan filter setup. Filters a huge volume of air and most of the dangerous fumes/smoke from soldering and welding are the particulates and not vapor from the papers ive read so a good hepa filter will protect you and your fam from experimenting indoors. I use one in my soldering area and it keeps the air fresh and clean.

This one is pulling double duty keeping the drywall dust to a minimum while i fix my basement and needs new filters soon but they can be found for $20 a 4 pack pretty reliably