"Copper/nickel sandwich" buses for series connections

Batteries, Chargers, and Battery Management Systems.
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srapy   1 W

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Re: "Copper/nickel sandwich" buses for series connections

Post by srapy » Jul 04 2021 12:09pm

These are pictures of my selfmade battery for my EM Escape 2019.
It’s a 20S 48Ah battery with Samsung 40T Cells in 12P configuration spot welded in sandwich style 0,2mm copper and 0,15mm nickelstrip.
110J on the kWeld but I had to spot weld twice the same place while cross swapping the electrodes on the second weld. Weld were about 1580A. That way made the best results.
All in all 2880 welds for this battery.
I am using this battery since 3 months and about 15 rides now. Cells stay nicely balanced after usage. 320A Peak showed no problems.

Facebook post with more pictures: https://www.facebook.com/groups/endless ... 21934387/
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spinningmagnets   100 GW

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Re: "Copper/nickel sandwich" buses for series connections

Post by spinningmagnets » Jul 04 2021 12:30pm

Thanks for posting those pics...

Electric Motion "EM Escape"...

Image

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srapy   1 W

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Re: "Copper/nickel sandwich" buses for series connections

Post by srapy » Jul 04 2021 12:40pm

You chose the 2020 model. The 2019 model looks like the attached picture. They have a different battery casing and different cell types.
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Rio   1 mW

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Re: "Copper/nickel sandwich" buses for series connections

Post by Rio » Jul 06 2021 4:28am

I'm really excited to see this method being more widely adopted. It has been a full two years since Ron "Spinning Magnets" wrote this article https://www.electricbike.com/introducti ... ng-part-3/

It inspired me to experiment and then share about the efficacy of this method. It was about three years ago that I began being serious about building batteries after I learned about and purchased a kWeld on advice that Ron had shared publicly about the outstanding engineering Frank employed in the device and the value and utility it offered.

I'd like to offer a heart felt thanks to Spinning Magnets for unremittingly being as trustworthy as possible while doing a great job sharing technology that can support our work on light electric vehicles as early as possible.

Ron, your work to help us be in the know created a big positive impact in my life, so thank you!

In the same spirit, here is an image for 14s SurRon packs. Four layered cake for 60V, and five layered cake for 72V
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john61ct   100 GW

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Re: "Copper/nickel sandwich" buses for series connections

Post by john61ct » Jul 06 2021 6:31pm

Yes, this method's come a long way!

Link to that case?

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spinningmagnets   100 GW

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Re: "Copper/nickel sandwich" buses for series connections

Post by spinningmagnets » Jul 06 2021 7:16pm

Thanks! That's very professional-looking. Well done, sir...well done!

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Re: "Copper/nickel sandwich" buses for series connections

Post by john61ct » Jul 07 2021 4:04am

OK, vague idea maybe OT but IMO next-level, possibly can be productized

Copper sheeting, thickest possible that works with Kweld, optimised.

Circles stamped out of the optimal nickel sheet/strip fixed on top of the copper,

precisely located for a given size battery

fixed in place using a conductive adhesive.

Use tin-snips to cut out the shapes needed for your unique pack.

Above concept as is, good enough for those happy with the idea of a permanent weld directly to the battery.

But for those looking for no-weld solderless ability to easily atomize/rebuild their packs,

this sheeting gets welded at the factory to strong but thin little button/disc **magnets** (props to goat guy)

End user now does not even need the Kweld!

Whaddya'll think?

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Cowardlyduck   1.21 GW

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Re: "Copper/nickel sandwich" buses for series connections

Post by Cowardlyduck » Jul 07 2021 5:17am

I definitely like the idea of precisely located nickel. My main concern with this whole idea is being able to accurately locate the positive cell end under a sheet of copper you can't see through.

That raises the question...for those who have done it...how are you ensuring you don't miss the positive cell end when welding?

Cheers

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Re: "Copper/nickel sandwich" buses for series connections

Post by spinningmagnets » Jul 07 2021 7:43am

I'll find the pic tonight, but one builder used a thin opaque sheet of material that you could see through.

After all the cells were in their holders, he overlaid it to draw the bus shapes, and also to mark the center of each cell.

This issue of cell location is important when using a wide copper sheet for the bus (seems it would be faster and easier than many small strips).

I immediately noticed that when someone used the nickel "ladder" style as the welding cap, that it was not only fast and available, it locates each cell automatically.

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Re: "Copper/nickel sandwich" buses for series connections

Post by john61ct » Jul 07 2021 9:37am

Just spitballin' still, in a primitive DIY context

maybe still allowing for mass production, obviously a full fledged factory would be different

If cellholders were being used, once each overall side was assembled as one piece,

that could be laid over the corresponding copper sheet and a per-cell center pin hole punched out. I think could be done within a couple mm by eye, or a precisely sized disk could be used with a

The magnets positioned to the copper sheet with a **tiny** drop of conductive adhesive placed in the concave depression.

The circular nickel disk similarly fixed centered using the concave side.

The sheet magnet side up, the assembled pack in cell holders precisely positioned on top, then carefully flip and weld.


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spinningmagnets   100 GW

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Re: "Copper/nickel sandwich" buses for series connections

Post by spinningmagnets » Jul 07 2021 8:30pm

viewtopic.php?f=14&t=84680&start=500#p1654650

ES member "pbert"
copper = 0.15mm
nickel = 0.2mm
spot welder = malectrics
spot welder setting = 26 ms pulse

Image

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Re: "Copper/nickel sandwich" buses for series connections

Post by Darren2018 » Jul 07 2021 11:11pm

Here is my 22S14P VTC6 HG2 hybrid battery. I couldn't afford the extra VTC6 needed so I went with HG2.

There is a total of 470g of copper over the full battery.

I used 6mm squares of 0.1mm nickel and welded as close as I could to the corners to make the most of the 1750A my welding battery can supply. I learned that decreasing the current by 30% required almost 100% more weld time on my particular setup. Much past 30m/s is not worth it imo. I don't like to profile my tips too sharp due to the erosion so I will be making an adjustable current sandwich welder that will do 2500A for the more stubborn materials. I also want to experiment with dual pulses as this might be able to temporarily increase the resistance of the copper.
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Re: "Copper/nickel sandwich" buses for series connections

Post by Overclocker » Jul 22 2021 4:29am

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RIP TEST. 0.1mm copper. 0.1mm nickel-plated steel.

copper "dots" left on the cell's metal case. definitely a strong connection

btw this is actually easier to weld than a single layer of 0.15mm pure nickel because nickel tends to stick to the electrode, steel doesn't

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spinningmagnets   100 GW

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Re: "Copper/nickel sandwich" buses for series connections

Post by spinningmagnets » Jul 22 2021 3:41pm

Where did you source the 0.10mm nickle-plated steel? That is looking like the best material for caps/parallel strips.

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Re: "Copper/nickel sandwich" buses for series connections

Post by Darren2018 » Jul 23 2021 2:38am

spinningmagnets wrote:
Jul 22 2021 3:41pm
Where did you source the 0.10mm nickle-plated steel? That is looking like the best material for caps/parallel strips.
I buy mine from Lucy's quality store on Aliexpress. They also sell 0.1mmx2/3/4mm for cell fuses. On this 10S8P practice battery I used 0.1mmx2mm which is good for around 4A continuous. If anyone else is thinking of using nickel plated steel for fuses make sure you seal the battery because they are quite thin.
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You can also buy 0.15 nickel plated steel in an offset pattern from the E-fire store on Aliexpress. I used a 3D printed template to align the weld spots on the last copper battery I built but this stuff would be helpful for people who don't have enough welding amps to weld pure nickel or can't be bothered with a template on an offset battery.
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Last edited by Darren2018 on Jul 23 2021 3:08am, edited 1 time in total.

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Re: "Copper/nickel sandwich" buses for series connections

Post by Darren2018 » Jul 23 2021 2:49am

Another thing that I generally use the copper tape for is busbars and flat cables. Here is a practice 10S10P battery I made:
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Cowardlyduck   1.21 GW

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Re: "Copper/nickel sandwich" buses for series connections

Post by Cowardlyduck » Jul 23 2021 3:08am

Darren2018 wrote:
Jul 23 2021 2:38am
I used a 3D printed template to align the weld spots on the last copper battery I built but this stuff would be helpful if you don't have enough welding amps to weld pure nickel or can't be bothered with a template on an offset battery.
IMG_4612.JPG
That is what I need. Would you mind sharing the STL or URL for that please.
Cheers

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Re: "Copper/nickel sandwich" buses for series connections

Post by Darren2018 » Jul 23 2021 3:31am

Cowardlyduck wrote:
Jul 23 2021 3:08am
Darren2018 wrote:
Jul 23 2021 2:38am
I used a 3D printed template to align the weld spots on the last copper battery I built but this stuff would be helpful if you don't have enough welding amps to weld pure nickel or can't be bothered with a template on an offset battery.
IMG_4612.JPG
That is what I need. Would you mind sharing the STL or URL for that please.
Cheers
Use tinkercad it's free. I can send you the STL I made but it is custom to my last build. I used VTC6 + HG2 with an extra wrap and no cell spacer. The VTC6 and HG2 are noticeably larger than 18mm, the extra wrap on each cell increases the diameter further and your printer calibration will likely be slightly different too. In all honesty you are better off making it yourself and doing a test print to make sure it lines up properly because if it is off you could have a very bad day.

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Re: "Copper/nickel sandwich" buses for series connections

Post by john61ct » Jul 23 2021 5:34am

Link to the copper "tape"?

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Re:

Post by Darren2018 » Jul 23 2021 5:56am

john61ct wrote:
Jul 23 2021 5:34am
Link to the copper "tape"?

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Re: "Copper/nickel sandwich" buses for series connections

Post by Cowardlyduck » Jul 23 2021 7:40am

Thanks Darren!
You make some good points I hadn't considered regarding the positioning. I will do as you suggest when I get around to doing this.

Cheers

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Re: "Copper/nickel sandwich" buses for series connections

Post by Darren2018 » Jul 23 2021 9:28am

Cowardlyduck wrote:
Jul 23 2021 7:40am
Thanks Darren!
You make some good points I hadn't considered regarding the positioning. I will do as you suggest when I get around to doing this.

Cheers
You could decrease/increase the scale but because I made the original file with cylinders and a set ID for the weld spot it might not fit your setup very well. Maybe someone could make a generator? When using certain cell spacers or even a double wrap with sheets of copper it is very easy to blow a hole through the base of the cell due to bad alignment. Copper can also not be welded to copper very well with the average current most hobby welders supply so you need to be exactly on the right spot if you are using small squares with multiple layers.

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Re: "Copper/nickel sandwich" buses for series connections

Post by Rio » Jul 25 2021 11:17pm

Cowardlyduck wrote:
Jul 07 2021 5:17am
I definitely like the idea of precisely located nickel. My main concern with this whole idea is being able to accurately locate the positive cell end under a sheet of copper you can't see through.

That raises the question...for those who have done it...how are you ensuring you don't miss the positive cell end when welding?

Cheers
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Cutting a jig like this is the best thing I could come up with. This jig is for the Eleek frame; I was able to order a number of their strong battery boxes that bolt right into the frame, so it made sense to come up with a solution to feel confident placing each tab to get through a build quicker. I still have to stop and manage the shape of my tips once or twice a side, and five of these bricks are required.

I could use one of these for the Sur-Ron template I posted above :)

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Re:

Post by Rio » Jul 25 2021 11:42pm

john61ct wrote:
Jul 06 2021 6:31pm
Yes, this method's come a long way!

Link to that case?
It's the stock case
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Re: "Copper/nickel sandwich" buses for series connections

Post by ZiaMag » Jul 26 2021 2:40am

Cowardlyduck wrote:
Jul 07 2021 5:17am
I definitely like the idea of precisely located nickel. My main concern with this whole idea is being able to accurately locate the positive cell end under a sheet of copper you can't see through.

That raises the question...for those who have done it...how are you ensuring you don't miss the positive cell end when welding?

Cheers
This was a major concern for me as well in the planning phase of my battery.

This is where using Inkscape (the open source alternative to Adobe Illustrator) really started to make sense regarding the design platform I chose. I apologize for reusing the same pics I posted on page 3, but the info needed is in these two pics so there ya go..

I designed everything in Inkscape. The cell holder plates, the copper bus plates, etc... no other software was used because I'm comfortable in Inkscape, and there was no reason to use anything else. Like any vector-based software you can set up and refine a grid in which all else can be based on, or not if you choose. Once I had the cell holder plates cut on my CNC from 3/8" polypropylene (a common kitchen cutting board from the dollar store) and the cells fit snuggly, I then knew the grid I had setup in Inkscape was then set in stone. The grid intersections were located at the center of the cell holes, and with snapping enabled at grid line intersections it made everything else fall into place AKA made the any remaining measuring or alignments quick, easy work.

You can see in the screen grab every component and design choice layered and visible. The beauty of working in SVG (vector) files is the cross compatibility with other software. When I drew out the copper plates I then drew the "slit"- the elongated oval shape that was to sit directly center on each cell, and center-snapping made that alignment over the cell accurately. To do a quick test against the physical cells in their cell holder plate, I made the copper plate/slit artwork the only visible layer in Inkscape, and simply printed the artwork out on a cheap inkjet printer onto common Vellum paper. From there, seeing that the geometry was exactly matching the physical battery, I was then able to take the SVG file (default vector art file type) and import it into Easel. I used Easel because it can accept SVG files and it's just dead simple to use, and knowing the file was dimensionally accurate it was just a few clicks to get my CNC to cut the copper plates exactly as they were in the file/printed on Vellum paper.

Once I had the copper bus plates cut, I just had to stay fairly close the "slit" cutout with the weld probes, as I knew that cutout was dead center to the physical cell below it.
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