Spot Welding Copper Strips to 18650 Battery Cells

Batteries, Chargers, and Battery Management Systems.
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spinningmagnets   100 GW

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by spinningmagnets » Jun 01 2019 1:09pm

I'm looking forward to retirement, because then I would have had the time to perform dozens of experiments that have been on the back burner for a couple years. Making a sandwich of copper/nickel is affordable and easily done with existing supply-line materials. DIY nickel-plated copper? what thickness of nickel is best? Maybe nickel-plated aluminum? Stainless plated aluminum? Anodized aluminum? Brass-plated aluminum/copper?

I was immediately reminded about a shill who posted a while back, and even though he only posted one of his companies products, it was worth knowing about, called SigmaCLAD. (original ES post here, https://endless-sphere.com/forums/viewt ... &start=700 )

https://chargedevs.com/features/enginee ... -industry/
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I was intrigued by the addition of a layer of stainless steel, which has an IACS conductivity rating of 3/100, compared to nickel at 23/100. Of course that makes it an excellent choice to easily spot-weld, but even as thin as its cross section would be, I think its a bad idea for ebike packs due to the horrible amount of resistance. And if you do add stainless, why add an additional layer of nickel? You can't always trust what manufacturers claim about their products, but we can still sometimes learn something valuable that might apply to us.

My first reaction was, why not just have nickel-clad copper? (cladding is a dry-process of bonding by rolling pressure, rather than electro-plating with chemicals). Wouldn't a three-layer material be cheaper to make than a five-layer material? The company PR release answered that question by saying the high conductivity of the copper core "overwhelmed" the spot-welding process. Of course, their customers may have demanded a material with no split, which would have forced the current direction through the cell-tip, rather than side-stepping through the bus itself.

I do believe it is possible for the cladding process to make bus material cheaper than electro-plating. They also mention that the symmetry of the clad materials helps it retain its shape when it heats up. If there were only two layers, the copper might expand from heat faster than the nickel, causing a pressure for the strip to bend. That being said, our goal is to allow a DIY battery pack that does not get hot when providing 15A-20A peaks per cell.
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Is thin stainless cheaper than pure nickel and readily available locally in major cities? (doesn't need to be ordered). The lower layer would NEED to be nickel instead of stainless, because its conductivity is 23/3 better (7 times?) than stainless. If someone here got stuck with an order of nickel-plated steel ribbon (after they ordered pure nickel ribbon) then, the Ni-plated steel would likely be fine for the top cap...

I'm even now wondering if yellow brass would be acceptable for the lower layer. Its conductivity is less than copper (so it is more weldable with existing DIY machines), but conducts better than nickel...28/100, compared to 23/100... Brass is soft enough to be cut by scissors, and it is cheaper than Nickel.

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garolittle   100 W

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by garolittle » Jun 01 2019 1:16pm

I remember that post. Very interesting concept.
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SirLongAss   100 mW

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by SirLongAss » Jun 01 2019 7:49pm

I finished building a 52v 13.6 ah battery with nickel(0.2mm) and copper(0.15mm) sandwich taps. It's kind of a pain in the rear.

Keep in mind. I was using a Malectrics Arduino Battery Spot Welder with a 800CCA car battery.

I had to set my welder to 40ms(normally I can weld 0.2mm nickel with 16ms) pulse time to get these to stick and oh boy did my welding probes get hot af real quick. So I had to take a few breaks. Also, trying to get one sandwich tap to weld to another is not recommended as it doesn't seem to hold very well and just pops off half the time.

Maybe playing around with different ratios of nickel to copper will fix some of the issues I encountered.

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ridethelightning   1 MW

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by ridethelightning » Jun 01 2019 8:12pm

sounds like your max pulse current isnt high enough. if it takes 40ms to make the weld, i think thats too long and will probably dump too much heat into the weld. your looking for a massive burst of amps in like 7ms or something.

i think you would need ballpark 2000A to attempt copper welding, with or without nickle sandwitch
(based on other posts and research on es)

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by SirLongAss » Jun 01 2019 8:27pm

ridethelightning wrote:
Jun 01 2019 8:12pm
sounds like your max pulse current isnt high enough. if it takes 40ms to make the weld, i think thats too long and will probably dump too much heat into the weld. your looking for a massive burst of amps in like 7ms or something.

i think you would need ballpark 2000A to attempt copper welding, with or without nickle sandwitch
(based on other posts and research on es)
All my welder does is shorts a 800CCA car battery for the amount of milliseconds it is set to. No control over the pulse current lol.

Even though it has some issues, I think this is a good solution vs buying that $10,000 welder at the start of this thread.

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by kdog » Jun 01 2019 9:15pm

WTF!!
IT WORKS! easy as pie. It's like the copper isn't even there. The nickel punches a hole straight through and welds to the can, fasting the copper no prob.
I did .1mm cu for all tests
.1mm Ni on top was dead easy but a littleweak as both strips a re weak.
.15mm Ni was probly the best all round.
.2mm Ni was starting to have weaker welds but with a bit more power it would've fine.
This was a very quick test (5mins worth)
Would've saved a shit ton of headaches when I did my battery a year ago... The one with the punched copper
In all my testing can't believe i didn't stumble across this...(%$#*!)
Deleted edit
Last edited by kdog on Jun 01 2019 9:53pm, edited 4 times in total.

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by kdog » Jun 01 2019 9:21pm

A pic for you all.
On the .1 Ni you can see it was a bit hot but the. 15 Ni is pretty good and has good much strength.
Same power level for all.
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Real quick test
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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by kdog » Jun 01 2019 9:27pm

.1mm torn off to see underside.
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ridethelightning   1 MW

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by ridethelightning » Jun 01 2019 10:21pm

looking nice! :D

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ridethelightning   1 MW

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by ridethelightning » Jun 01 2019 10:25pm

SirLongAss wrote:
Jun 01 2019 8:27pm
All my welder does is shorts a 800CCA car battery for the amount of milliseconds it is set to. No control over the pulse current lol.

Even though it has some issues, I think this is a good solution vs buying that $10,000 welder at the start of this thread.
yes you do have control of the current! just get more batteries!
if you could find 3* 800cca batteries and parallel them, id say you would be in the zone.
ofcourse, depending on your welder fets etc, you will probably need to look at using shotky diodes to control the avalanch current, or make a new power switch with more/better fets.

might be easier to get some high c lipo to power it than sla.

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by SirLongAss » Jun 01 2019 10:46pm

ridethelightning wrote:
Jun 01 2019 10:25pm
SirLongAss wrote:
Jun 01 2019 8:27pm
All my welder does is shorts a 800CCA car battery for the amount of milliseconds it is set to. No control over the pulse current lol.

Even though it has some issues, I think this is a good solution vs buying that $10,000 welder at the start of this thread.
yes you do have control of the current! just get more batteries!
if you could find 3* 800cca batteries and parallel them, id say you would be in the zone.
ofcourse, depending on your welder fets etc, you will probably need to look at using shotky diodes to control the avalanch current, or make a new power switch with more/better fets.

might be easier to get some high c lipo to power it than sla.
Funny enough it is on my mind. I'll have to either upgrade my welder or build another. Mine is capped at 1200CCA but from what I've read it doesn't last long at anything over 800CCA.

Nah not lipos. I got the perfect cells for that. (something that wont puff up and can be left fully charged)

Image

I bought 3 of them a few months back and they each will do 500A pulls. 4 in parallel and you got your 2000A pulse.

https://www.aliexpress.com/item/3pcs-40 ... 2e077canK5

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ridethelightning   1 MW

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by ridethelightning » Jun 02 2019 12:33am

holy crap! they look like the perfect thing.
rebuilding your welder may not be so hard. im at that point now, modifying a riba welder
https://endless-sphere.com/forums/viewt ... 4&t=100435

basically use the low current timing circut to provide the 12v pulse for the fets and build a larger switch for the high current , using more/better fets and a few diodes.

im just waiting for my fets to arrive.

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spinningmagnets   100 GW

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by spinningmagnets » Jun 02 2019 12:27pm

Here's a video about spot-welding aluminum, using this trick of making a steel sheetmetal sandwich with the aluminum in the center. Start at 1:11

https://youtu.be/gcgC3V3mkcw?t=71

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garolittle   100 W

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by garolittle » Jun 04 2019 11:58am

Great discussion. Very interesting ideas. I am still trying to convince my wife that the $10k spot welder would be a great Fathers Day gift. No luck yet. :-)
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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by Strizh » Jun 26 2019 5:32am

Hey guys!

Here's a device that I've made to weld copper strips to 18650 cells using standard TIG welding machine. Please check it out. I will be very grateful for any kind of feedback.

https://youtu.be/bYDD5-u3WKw
https://youtu.be/xgTehS_9Dfg

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by litespeed » Jun 26 2019 6:41am

That is awesome.....basically you made a pulse arc welder. Very cool!

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spinningmagnets   100 GW

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by spinningmagnets » Jun 26 2019 12:54pm

Just did a quick google. On youtube, a $1000 TIG welder is considered entry-level and "affordable". That being said, this is useful info...

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Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by mattthemuppet » Jun 26 2019 2:20pm

kdog wrote:
Jun 01 2019 9:15pm
WTF!!
IT WORKS! easy as pie. It's like the copper isn't even there. The nickel punches a hole straight through and welds to the can, fasting the copper no prob.
I did .1mm cu for all tests
.1mm Ni on top was dead easy but a littleweak as both strips a re weak.
.15mm Ni was probly the best all round.
.2mm Ni was starting to have weaker welds but with a bit more power it would've fine.
This was a very quick test (5mins worth)
Would've saved a shit ton of headaches when I did my battery a year ago... The one with the punched copper
In all my testing can't believe i didn't stumble across this...(%$#*!)
Deleted edit
fabulous, thanks for the heads up! I read through this whole thread, what a journey :) I'll be rebuilding a Giant Road-e battery in a month or so, using Sanyo GA cells from Michal and a Malectrics tab welder (both found through research on here!), and I've been thinking of ways of reducing heat in the battery especially riding in hot Texan summers. I have some 0.15mm x 10mm Ni tape and I've just ordered some 0.1mm Cu sheet (10x100cm). Can't wait to get going on this and get my range/ power back.

this place is such a fabulous resource :D

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