Spot Welding Copper Strips to 18650 Battery Cells

Batteries, Chargers, and Battery Management Systems.
greenno   100 µW

100 µW
Posts: 8
Joined: Sep 26 2018 2:44pm

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by greenno » Oct 22 2018 9:23pm

Why would a copper sheet with holes and nickel plated stripes welded across holes and then welded to battery surface be better than just solid nickel welded across battery ends, am I missing something?

User avatar
spinningmagnets   100 GW

100 GW
Posts: 11198
Joined: Dec 21 2007 10:27pm
Location: Ft Riley, NE Kansas

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by spinningmagnets » Oct 22 2018 10:31pm

Nickel has about 1/4th the conductivity of copper, which also means that it has about four times the resistance. At fairly average amp levels, then using only nickel would be fine. At high amps, the nickel buses begin acting like a heater. They would convert a higher percentage of the battery watts into waste-heat.

Resistance compounds over conductor length. As long as the nickel portion is short, it lessens the negative impact. Also, when nickel buses get hot, they stay hotter longer than copper. In the style I described, the copper portion would also act as a heat-sink, to pull heat away from the short nickel part, and then copper would shed that heat much faster than a nickel bus.

It all comes down to how many amps do you want to use? For common 10A cells, the common 0.20mm thick X 7mm wide nickel ribbon is fine. The 30Q can put out 15A, and the HG2 can put out 20A.

If you have a 5P pack of HG2 cells, the cells can put out a combined total of 100A, and putting 100A through 0.20mm nickel is not an optimal method.

It also doesn't hurt that copper is cheaper than nickel. And if you are building your own pack, why not?

greenno   100 µW

100 µW
Posts: 8
Joined: Sep 26 2018 2:44pm

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by greenno » Oct 23 2018 11:04am

Thanks for the reply. I'm guessing that a solid nickel plate would never get hot enough to generate enough heat to adversely effect the performance of the batteries I'm using. Uning the Sanyo 18650GA cells rated for 10a discharge. Using 126 cells in a 14s 9p configuration and making sure I have a minim of six connection jumpers between the paralleled cells. With the smaller strips rated around 7a and a controller limiting my max amperage draw at 30a I feel I will be increasing my conductivity with the plate material. Not having the best luck when spot welding my top strips. Bottom layer directly on battery is 100% good but adding additional stripes on top doesn't penetrate enough to get good penetration using the unit that I have. We'll see how the plate works when I get it, It's out of stock currently. Thanks.

999zip999   100 GW

100 GW
Posts: 8894
Joined: Jan 10 2010 1:40pm
Location: Dana Point So. Cal

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by 999zip999 » Oct 23 2018 1:46pm

Spinngmanets I have the very same idea. I did post some time back. I do have access to copper but if I could get a sample of the nickle plate of p and s. I would cald it with a sheet of copper as in my brain. Im thinking the nickle plated cooper with a layer of copper except for holes above the cellsfor welding and the the cooper surrounding and making the series connection for higher amps.

User avatar
spinningmagnets   100 GW

100 GW
Posts: 11198
Joined: Dec 21 2007 10:27pm
Location: Ft Riley, NE Kansas

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by spinningmagnets » Nov 20 2018 12:05am

This is an example of several ideas I have been growing fond of.

Honeycomb layout of cylindrical cells
copper bus-plates for high conductivity and heat sinking/radiation of amps heat
nickel tabs to connect cell-ends to bus-plate

By connecting the nickel tabs to the copper bus-plate before you spot-weld cells, you can use high heat with a simple and cheap 2V / 700A DIY RSU. After you are done and the work-piece cools off, you can move on to spot-welding the cells onto the nickel tabs by common methods

https://czguisheng.1688.com/
BatteryBusCopperNickel1.png
A
BatteryBusCopperNickel1.png (731.64 KiB) Viewed 1465 times
BatteryBusCopperNickel2.png
B
BatteryBusCopperNickel2.png (609.71 KiB) Viewed 1464 times

djonojono   1 µW

1 µW
Posts: 2
Joined: Nov 20 2018 3:16am

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by djonojono » Nov 20 2018 4:14am

hi everyone, ive been reading this thread and insterested in it.

but i have a question, is there anyone try the nickel plated(coated) copper strip out there? i have nickel plated copper 0.1mm thick and 0.2 copper strip, but never try it with my pack(just got few meter's sample from my supplier)
Image
this is the link for nickel if someone interested https://bangteng.en.alibaba.com/product ... ttery.html

im wondering if its have side effect,comparing with tesla pack that have its battery connected with wired that act as fuse.
im still thinking why tesla use that kind of technology(fuse),

User avatar
Willow   10 kW

10 kW
Posts: 805
Joined: Sep 06 2011 7:42pm
Location: Tasmania

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by Willow » Nov 20 2018 4:39am

where did you get nickel plated copper?

User avatar
spinningmagnets   100 GW

100 GW
Posts: 11198
Joined: Dec 21 2007 10:27pm
Location: Ft Riley, NE Kansas

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by spinningmagnets » Nov 20 2018 7:48am

Part of the reason that Tesla added an individual cell-fuse to their design was because it allowed them to remove some of the standard internal safety features in order to slightly increase the Amp-hour volume of the active material.

Another reason is that some of their cars are likely to be in a crash, which is unlike a powerwall that is stationary. An ebike battery might also be involved in a crash, but it is a much smaller pack and a battery fire resulting from an ebike crash is unlikely to be fatal.

I am interested in the 0.20mm thick copper bus with nickel plating, would it spot-weld easily?

djonojono   1 µW

1 µW
Posts: 2
Joined: Nov 20 2018 3:16am

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by djonojono » Nov 20 2018 8:56am

Willow wrote:
Nov 20 2018 4:39am
where did you get nickel plated copper?
I got it from china, bangteng in alibaba website.
Never try it on my pack, i just ask free sample for my trial error.

spinningmagnets wrote:
Nov 20 2018 7:48am
Part of the reason that Tesla added an individual cell-fuse to their design was because it allowed them to remove some of the standard internal safety features in order to slightly increase the Amp-hour volume of the active material.

Another reason is that some of their cars are likely to be in a crash, which is unlike a powerwall that is stationary. An ebike battery might also be involved in a crash, but it is a much smaller pack and a battery fire resulting from an ebike crash is unlikely to be fatal.

I am interested in the 0.20mm thick copper bus with nickel plating, would it spot-weld easily?
Thanks for your answer, i was confused why, some people in my office says individual cell can failed and affect the others. But i dont know why the batteries failed. Internal short or the cell short itself or maybe something i'm still dunno

E bike fire, actually i've experience it before. My 10p24s pack shorted because unknown cause(recycle batteries etc etc).
The fire is hillarious. I dont want to experience it again lol.

For the 0.2mm copper strip , i'm havent try it to my pack yet. I got the sample still in pure copper form, not nickel plated. I'm still try it to be plating soon. But 0.1 thick was welded really easy.

User avatar
spinningmagnets   100 GW

100 GW
Posts: 11198
Joined: Dec 21 2007 10:27pm
Location: Ft Riley, NE Kansas

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by spinningmagnets » Nov 20 2018 12:20pm

"...people in my office says individual cell can failed and affect the others..."

If one cell in a 5-cell parallel string experienced an internal short, it will get very hot very fast, which will make the short larger.

It will quickly become as if that cell was removed, and replaced with a thick copper wire, which will make the other four cells in the 5P string begin to rapidly overheat.

Even though those five cells will not cause an electrical short in the P-string next to them (connected in series), the heat of five cells shorting can cause the rest of the cells to cascade into an overheated condition, like dominoes.

Having each cell fused will not stop one cell from catching fire due to an internal short, but it separates that cell from the rest. Hopefully the overheating stops at one cell, but even if it's heat still spreads, a fuse will slow down those reactions.

User avatar
garolittle   100 W

100 W
Posts: 284
Joined: Mar 03 2018 1:06pm
Location: Augusta, GA U.S.A

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by garolittle » Nov 20 2018 5:24pm

This is so cool. That looks like a perfect design for high amp rated projects. I would think this design combined with the Kweld unit would make for a powerful 18650 battery pack. :shock:
64E8E532-C40A-4F91-A9D1-E88080052811.jpeg
64E8E532-C40A-4F91-A9D1-E88080052811.jpeg (168.65 KiB) Viewed 1393 times
VenomKarts, LLC
VenomKarts.com
Augusta, GA

kdog   10 kW

10 kW
Posts: 587
Joined: Feb 02 2014 9:22pm
Location: hobart, tasmania

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by kdog » Nov 21 2018 5:36pm

If you can get your cell position precision to a high standard, then you could buy this pre- made and use some shears to cut to required shape. Damn! That would be very cool!
My problem with the glued cells was minor changes in position of the cells meant every piece was different. Cell holders or CNC cutout would solve this. Makes me want to build!

User avatar
garolittle   100 W

100 W
Posts: 284
Joined: Mar 03 2018 1:06pm
Location: Augusta, GA U.S.A

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by garolittle » Nov 21 2018 5:49pm

kdog wrote:
Nov 21 2018 5:36pm
If you can get your cell position precision to a high standard, then you could buy this pre- made and use some shears to cut to required shape. Damn! That would be very cool!
I agree. This could be a “game changer” for higher amp applications.
VenomKarts, LLC
VenomKarts.com
Augusta, GA

protoham   10 µW

10 µW
Posts: 5
Joined: Apr 18 2019 1:21pm

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by protoham » Apr 18 2019 1:27pm

I just got pricing from Sunstone for this welder, I was really considering buying one > Sit Down ........... Over $24,000.00.

User avatar
garolittle   100 W

100 W
Posts: 284
Joined: Mar 03 2018 1:06pm
Location: Augusta, GA U.S.A

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by garolittle » Apr 18 2019 6:49pm

protoham wrote:
Apr 18 2019 1:27pm
I just got pricing from Sunstone for this welder, I was really considering buying one > Sit Down ........... Over $24,000.00.
Yeah but you would be the envy of everyone here. :-)
VenomKarts, LLC
VenomKarts.com
Augusta, GA

protoham   10 µW

10 µW
Posts: 5
Joined: Apr 18 2019 1:21pm

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by protoham » Apr 19 2019 5:43pm

So what would happen if you put a hole in the copper so that one probe goes directly to the battery and the other probe on the copper tab. And it would be wise to put the + side on the battery and the - on the tab, so you get an electron flow from the copper to the "steel/ al / zinc" battery contact. Of course you would want to use tungsten tips. Has anybody tried this??

I can't be the first to think of it.

protoham   10 µW

10 µW
Posts: 5
Joined: Apr 18 2019 1:21pm

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by protoham » Apr 19 2019 5:58pm

OK Guys I am designing a battery pack to do something crazy and need help for safety.

I am looking at mounting 9 A123 ANR26650 cells together in series then take 3 of these and connect them in Parallel to get a battery pack that will generate 90A continuous at 28V, with a burst of 350A for 100mS. This has a Capacity of 7.5Ah. Of course this is all connected with copper. I am monitoring each cell for voltage, have a limited 3 Amp charge which will shut down if a cell opens or shorts. I actually have this built.

What are my risks.

User avatar
garolittle   100 W

100 W
Posts: 284
Joined: Mar 03 2018 1:06pm
Location: Augusta, GA U.S.A

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by garolittle » Apr 21 2019 10:44pm

protoham wrote:
Apr 19 2019 5:43pm
So what would happen if you put a hole in the copper so that one probe goes directly to the battery and the other probe on the copper tab...
Interesting idea. I suspect "spinningmagnets" is your best bet for an accurate answer to this question. My suspicion is that the copper will still disperse the heat too quickly for a consistent weld. However, you get lots of points for a cool idea. I hope it works for you. Keep us posted.
VenomKarts, LLC
VenomKarts.com
Augusta, GA

User avatar
spinningmagnets   100 GW

100 GW
Posts: 11198
Joined: Dec 21 2007 10:27pm
Location: Ft Riley, NE Kansas

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by spinningmagnets » May 31 2019 11:33pm

Don't know if this is legit, but it appears intriguing. Earlier in this youtube, he shows that he has a FET bundle (75 FETs) as the on/off switch. Probably way too many, but if you have a pile laying around, why not?

The 12V timer is powered by three 18650 cells in 3S / 1P (the red cells in the background). The timer link is in the top comment.

The power battery for the spot-welding appears to be 2S LiPo pouches. I don't see any components for recirculating currents when the switch goes off. (Inductance collapse voltage spikes)

Looks like he is successfully spot-welding 0.20mm thick copper to 18650's. There is no split down the center (I still believe a split would help). The odd thing is that he is making a sandwich (at 08:40) with copper touching the cell, and 0.20 nickel over top of it, then he applies the spot-weld.

The first part of the video he demonstrates spot-welding 0.15mm, 0.20mm, and 0.30mm nickel (with no copper sandwich).

https://youtu.be/4dZTGAcFmtA?t=649


SirLongAss   100 mW

100 mW
Posts: 47
Joined: Aug 26 2018 10:55am

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by SirLongAss » Jun 01 2019 6:18am

spinningmagnets wrote:
May 31 2019 11:33pm
Looks like he is successfully spot-welding 0.20mm thick copper to 18650's. There is no split down the center. The odd thing is that he is making a sandwich (at 08:40) with copper touching the cell, and 0.20 nickel over top of it, then he applies the spot-weld.

The first part of the video he demonstrates spot-welding 0.15mm, 0.20mm, and 0.30mm nickel.

https://youtu.be/4dZTGAcFmtA?t=649

I can confirm this works.

Image

I saw that video a few weeks ago and was amazed by how simple it was. I imagine it works almost like a HEAT round for a tank. Nickel has a much high melting point then copper. So the molten nickel probably just punches threw it and cools when it hits the nickel battery tap. Effectively bolting the copper in place.

I'm building a 52v battery today with this idea and will post results later.

kdog   10 kW

10 kW
Posts: 587
Joined: Feb 02 2014 9:22pm
Location: hobart, tasmania

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by kdog » Jun 01 2019 6:59am

Damn! I'm going to try it as well. Can't be that simple...we'll all have to go back to spotwelding school if it is.
Only 2 things I don't like in this video are how hard he's pressing on the electrodes and those fingernails :(

User avatar
DogDipstick   10 W

10 W
Posts: 68
Joined: Aug 19 2018 12:39pm
Location: Fleetwood Pa

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by DogDipstick » Jun 01 2019 7:40am

Old sheet metal workers trick for spot welding aluminum too...
750W @ 54.4v of raw BBS02 power takes me everywhere on my BD Motobecane...: Powered by Chevy.

User avatar
ridethelightning   1 MW

1 MW
Posts: 1869
Joined: Jul 21 2013 9:48pm

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by ridethelightning » Jun 01 2019 7:44am

SirLongAss wrote:
Jun 01 2019 6:18am
Nickel has a much high melting point then copper. So the molten nickel probably just punches threw it and cools when it hits the nickel battery tap. Effectively bolting the copper in place.
close i think. i think its working because the high resistance of the nickel is creating heat on the copper. its the same principle as tungsten tips, they actually have a high resistance so the current makes heat at that point that melts the copper. if the nickel was not there, there would not be enough heat created because the copper would just conduct the pulse without making enough heat

if nickel has a higher melting point as you say, it will help squash the copper as it melts. similar principal to tungsten, as tungsten stays very hard even when cherry red.

this looks to have an advantage over tungsten tips though cause the current path through the nickle strip to copper is so short. with the tungsten tips its effectively 5-10mm through a 1.5mm dia resistor, through the copper, battery shell, copper, 5-10mm resistor..... and i think that may stifle the current too much..damn why didnt i think of that!

i wish i could grab those clippers and get rid of the guys fingernails :mrgreen:

litespeed   100 kW

100 kW
Posts: 1368
Joined: Aug 11 2010 4:42pm
Location: St. Peters, Missouri

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by litespeed » Jun 01 2019 9:58am

That is pretty amazing....I’ll have to get some more copper and try that.

Tom
I'm married so you know I'm no stranger to pain!

User avatar
garolittle   100 W

100 W
Posts: 284
Joined: Mar 03 2018 1:06pm
Location: Augusta, GA U.S.A

Re: Spot Welding Copper Strips to 18650 Battery Cells

Post by garolittle » Jun 01 2019 11:01am

Possible “game changer”. Really cool concept.
VenomKarts, LLC
VenomKarts.com
Augusta, GA

Post Reply