kWeld - "Next level" DIY battery spot welder

Batteries, Chargers, and Battery Management Systems.
NetPro   100 mW

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Re: kWeld - "Next level" DIY battery spot welder

Post by NetPro » Nov 05 2020 12:14am

spinningmagnets wrote:
Nov 04 2020 10:25am
I would highly recommend investigating the copper/nickel sandwich method for welded buses. It's a proven method that provides more than three times the series current, while also running cooler and generating less voltage sag under load.

Nickel is a poor conductor, so increasing thickness from 0.15mm to 0.20mm is fighting to desperately increase conductivity 33%...using copper for series is a 300% improvement.

If corrosion from bare copper ribbon is a concern, Keith at 18650 heat shrink and cell holders has nickel-plated copper ribbon.
Yes, excellent suggestion that I will research and test.
Only downside is, since cooper's resistance is so much lower, it is harder to weld and you would probably need more power to get it to work. We'll see.
The thought of using copper (not sandwiched with nickel) occurred to me but I have read on the forums how much more difficult working with copper is when compared to pure nickel.
At that time I even looked at the ultrasonic welders available online but the price for a good one was a show stopper.

Anyhow, thanks for the suggestion! The first step is to buy good copper. . .

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Re: kWeld - "Next level" DIY battery spot welder

Post by spinningmagnets » Nov 05 2020 7:41am

viewtopic.php?f=14&t=108006

Molicel 21700 P42A cells, 0.10mm copper sheet, plus 0.15 nickel squares only to facilitate welding. 20S / 6P

kWeld used, setting is 50-Joule

Image

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Re: kWeld - "Next level" DIY battery spot welder

Post by NexusG » Nov 09 2020 1:50pm

Hi everyone,
Does a cheap crimp tool like this one is enough to assemble the kWeld ?
https://www.amazon.com/IWISS-Battery-Ca ... 739&sr=8-3

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Re: kWeld - "Next level" DIY battery spot welder

Post by pcmeiners1 » Nov 10 2020 12:26pm

This crimper should be more than enough, avoid soldering after crimping, it adds resistance.

Spinningmagnets, like the idea of little pieces of nickel to weld copper...a little effort to have bigger gains.

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Re: kWeld - "Next level" DIY battery spot welder

Post by nuxland » Dec 15 2020 1:56pm

Hey

I have a question about power source. Made myself a 12v power source from 6pcs of 3000F 2,7v ultracaps.
And somehow blowed off my malectrics v2.2 spot welder with 9ms pulse (two mosfets died)
So my question is, can kweld handle that or I need less powerfull powersource?
Electric kart 60kw: viewtopic.php?f=34&t=68543
100v 35Ah LiPo battery: viewtopic.php?f=14&t=97763
100v 25Ah LiFePo4 battery: viewtopic.php?f=14&t=85912
Scooter battery: viewtopic.php?f=14&t=108227#p1582703

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Inexpensive & SUPER Battery for Kweld

Post by Hosedragger » Dec 16 2020 7:09am

For the last couple years I've been using a DIY spotwelder using a microwave transformer and a controller from avdweb.nl in The Netherlands to build E-Bike packs. Results were not that spectacular especially with thicker tab material and 26650 batteries. So I recently purchased the Kweld kit and used an Optima Spiral AGM 750CCA car battery as the power supply. It worked better but lugging that HEAVY battery around was a PITA. So, I have several A123 36volt modules that use 48 ANR26650M1A LiFePo4 cells in a 12s4p configuration. Each of these cells are rated to provide a 120amps load for 10 seconds and 50amps continuous. I purchased them from Battery Hookup, and normally use them in E-Bike packs. Battery Hookup gets them in regularly but sells out quick because they are only $49.99. https://batteryhookup.com/products/a123 ... 0910137476


I reconfigured the module into a 14.4 volt 4s12p pack and this thing kicks ass as a power supply for the Kweld. Way better then the 750cca car battery and super light. When I ran Kweld calibration it showed 1436 Amps during the short test. I just wanted to share this info with others.

I don't have a video on the battery build, just photos. So here goes.
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With cover removed. There are several #10 torx screws holding the cover on, one under the label. Also remove 6 more screws to lift battery pack from the case. Removing the BMS requires cutting or unsoldering the connections along the edge of the board and unscrewing several torx screws. I cut the balance connectors with a knife and small snips. Be careful, don't cut yourself!
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I removed the upper and lower cell holder plates to access the batteries. The lower plate is a pain because the 4 cells on each end are joined together with an external buss. I had to cut those sheet metal busses between each of those end cells (8 in total) and fold the metal up so the lower black cell holder plate could be removed. After that I had to separate cells to reconfigure the pack. I did not want to spot-weld new tabs to the batteries. Sometimes pulling the old tabs from these cells can perforate the cell. So I cut the cell tabs apart along the red lines shown creating 12 sets of 4 cell packs. The cells sets are highlighted yellow. I then repositioned them into the areas that are highlighted blue. I've only highlighted 4 areas, but they repeat throughout the pack. I used small pieces of nickel plated copper strips as jumpers to rejoin the cells but in a 4s12p configuration. I also doubled-up the strip to create buss bars across the 12 batteries on both ends of the reconfigured pack. They were soldered to the tab material running between the cells. The 0.3mm thick nickel plated copper strip came from https://18650shrinkandcellholders.com/
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End view showing the two female output terminals. I disassembled the terminal assembly and soldered 8awg cables into them directly. Be careful, it's pretty easy to unsolder it from the board also. Oops, I did, but just had to wire wick the solder from board and resolder the terminal block back in.
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I cut and reconfigured the heavy original copper connectors, soldered them to the battery and bolted them to the original output terminals at the end of the case. Used a short piece of 8awg wire for the positive connection.
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8awg cables soldered into the output terminals. They go to the Kweld. Later on I may add a 4s BMS.

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Re: kWeld - "Next level" DIY battery spot welder

Post by ossivirt » Dec 17 2020 4:34pm

nuxland wrote:
Dec 15 2020 1:56pm
Hey

I have a question about power source. Made myself a 12v power source from 6pcs of 3000F 2,7v ultracaps.
And somehow blowed off my malectrics v2.2 spot welder with 9ms pulse (two mosfets died)
So my question is, can kweld handle that or I need less powerfull powersource?
Hello.

Someone can probably calculate how your capasitor bank behaves with kweld if you have datasheet for your caps. Or atleast ir value I think..

But I can only say that probably yes it can handle it. However if I had supercapasitorbank of unknown specs I would use adjustable cc/cv powersuply or dc converter to charge it to lowest possible voltage that kweld can operate (refer to manual). Then do calibration and check what the current was. Then raise voltage little and repeat untill you max your capasitor voltage or welding current goes close to 2000A overcurrent limit.

But if you don't have kweld yet then you need to get one :lol:

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Re: kWeld - "Next level" DIY battery spot welder

Post by nuxland » Dec 17 2020 4:43pm

ossivirt wrote:
Dec 17 2020 4:34pm
nuxland wrote:
Dec 15 2020 1:56pm
Hey

I have a question about power source. Made myself a 12v power source from 6pcs of 3000F 2,7v ultracaps.
And somehow blowed off my malectrics v2.2 spot welder with 9ms pulse (two mosfets died)
So my question is, can kweld handle that or I need less powerfull powersource?
Hello.

Someone can probably calculate how your capasitor bank behaves with kweld if you have datasheet for your caps. Or atleast ir value I think..

But I can only say that probably yes it can handle it. However if I had supercapasitorbank of unknown specs I would use adjustable cc/cv powersuply or dc converter to charge it to lowest possible voltage that kweld can operate (refer to manual). Then do calibration and check what the current was. Then raise voltage little and repeat untill you max your capasitor voltage or welding current goes close to 2000A overcurrent limit.

But if you don't have kweld yet then you need to get one :lol:
Already bought one yesterday :)
And read like 2h the thread and figured out the same that need to start from 8V and calibrate and see test result.
https://www.elfadistrelec.ee/Web/Downlo ... ng_tds.pdf
from the specs 220 micro ohm 0r 0,22 mohm. So 6 in series is 6x0,22=1,32mohm and what I read I need to add some 8awg cables to use it charged to 12v :) But as I have laboratory power supply I can start with 8V.
Electric kart 60kw: viewtopic.php?f=34&t=68543
100v 35Ah LiPo battery: viewtopic.php?f=14&t=97763
100v 25Ah LiFePo4 battery: viewtopic.php?f=14&t=85912
Scooter battery: viewtopic.php?f=14&t=108227#p1582703

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Re: kWeld - "Next level" DIY battery spot welder

Post by nuxland » Dec 23 2020 12:55pm

Finished my capacitor pack enclosure and added awg10 with xt90 for charging and awg6 with QS8S connector (its larger than xt150) for discharging. If awg6 is to large then I can change it to awg8 and xt150 connectors (will be making that output wire also).
Also printing out bottom enclosure with my ancient 3d printer that still works after 10 years :)
Now waiting for the kWeld, that should arrive on monday.
Attachments
Capacitors.jpg
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Electric kart 60kw: viewtopic.php?f=34&t=68543
100v 35Ah LiPo battery: viewtopic.php?f=14&t=97763
100v 25Ah LiFePo4 battery: viewtopic.php?f=14&t=85912
Scooter battery: viewtopic.php?f=14&t=108227#p1582703

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Re: kWeld - "Next level" DIY battery spot welder

Post by nuxland » Dec 28 2020 12:34pm

Got my kWeld and with 11V got these CAL numbers: 2,5mohmi and 1263A
Output cables are both 50cm so together 1m and intput cables are 45cm each, so together 90cm (but these are 6AWG).
So I entered 1,5m in cable lenght, because 90cm of 6AWG should be ~50cm 8AWG :)
But it seems I need to shorten these 6AWG cables (I was affraid that there would be to much current).

Tested these 4 cells with 20J and measured
13,5ms
1132A
1,17mR
28,6degrees
Attachments
kweld.jpg
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Electric kart 60kw: viewtopic.php?f=34&t=68543
100v 35Ah LiPo battery: viewtopic.php?f=14&t=97763
100v 25Ah LiFePo4 battery: viewtopic.php?f=14&t=85912
Scooter battery: viewtopic.php?f=14&t=108227#p1582703

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Re: kWeld - "Next level" DIY battery spot welder

Post by nuxland » Dec 28 2020 2:27pm

Shortened the wires and got 1700A CAL current with 12V.
Also told to the system that I have now 1,2m cables so overcurrent max should be 1800A in system now.
Resistance was also a little bit lower, at 2,48 mR
Attachments
kweld_12V_1700A.jpg
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Electric kart 60kw: viewtopic.php?f=34&t=68543
100v 35Ah LiPo battery: viewtopic.php?f=14&t=97763
100v 25Ah LiFePo4 battery: viewtopic.php?f=14&t=85912
Scooter battery: viewtopic.php?f=14&t=108227#p1582703

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flippy   10 MW

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Re: kWeld - "Next level" DIY battery spot welder

Post by flippy » Dec 29 2020 7:02am

get rid of the connector, bolt the welder to the capacitor block and make the leads longer. then you can probably also weld at a lower votage or use the voltage to better regulate the available current.
longer leads are more practical for making bigger batteries.
Lithium beats liquid dinosaurs.

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Re: kWeld - "Next level" DIY battery spot welder

Post by Hummina Shadeeba » Dec 30 2020 12:24pm

What settings u use for .1mm copper?

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Re: kWeld - "Next level" DIY battery spot welder

Post by ossivirt » Dec 30 2020 3:32pm

Hummina Shadeeba wrote:
Dec 30 2020 12:24pm
What settings u use for .1mm copper?
Around 50 joules with my 1500A battery. With copper amps matter a lot more because weld time should be as short as possible to make sure energy is used to weld and not just heating copper around the weld..

With nickel or steel on top method I have not tried yet but it should be better way to go..

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Re: kWeld - "Next level" DIY battery spot welder

Post by spinningmagnets » Dec 30 2020 4:49pm

The 0.10mm thick copper may sound thin, but since copper is four times more conductive, with 1/4th the resistance (compared to nickel), the 0.10mm copper is equal in current-carrying ability to 0.40mm thick nickel.

It's also cheaper and more readily available locally than nickel, plus easier to cut.

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Re: kWeld - "Next level" DIY battery spot welder

Post by Hummina Shadeeba » Jan 01 2021 7:12pm

ossivirt wrote:
Dec 30 2020 3:32pm
Hummina Shadeeba wrote:
Dec 30 2020 12:24pm
What settings u use for .1mm copper?
Around 50 joules with my 1500A battery. With copper amps matter a lot more because weld time should be as short as possible to make sure energy is used to weld and not just heating copper around the weld..

With nickel or steel on top method I have not tried yet but it should be better way to go..


it seems easier than the boss welder in that it has just one knob for joules but it expects you to figure your battery's internal resistance (how?)

https://www.keenlab.de/wp-content/uploa ... l-r3.0.pdf


i'd like to use it with my 5s litium iron battery at like 16 volts and need to maybe figure the wire length for that or i just keep firing from low joules and work my way up till it sticks? my wiring isnt longer than a meter.

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Re: kWeld - "Next level" DIY battery spot welder

Post by flippy » Jan 02 2021 6:21am

spinningmagnets wrote:
Dec 30 2020 4:49pm
The 0.10mm thick copper may sound thin, but since copper is four times more conductive, with 1/4th the resistance (compared to nickel), the 0.10mm copper is equal in current-carrying ability to 0.40mm thick nickel.
It's also cheaper and more readily available locally than nickel, plus easier to cut.
and it utterly destroys your welding tips.
Lithium beats liquid dinosaurs.

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Re: kWeld - "Next level" DIY battery spot welder

Post by nuxland » Jan 02 2021 9:13am

Wanted to test what is the max I can use with kWeld.
So shortened my welding cables to 40cm each and input cables are 15cm each but 6AWG so together should be 1m total lenght.
Had to lower voltage to 11,8V to be able to calibrate to 1971A (12,0V gave me overcurrent).
kweld_CAL_1971A.jpg
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And then tested to weld with 150J using 0.1mm nikkel to 0.5 copper (that I was using in my 25kwh A123 pack).
Got these values:
I=1834A
R=0.47mR
E=150.0J
t=136,61ms
Copper went rather hot and weld was so/so one I could tear apart and in another one nikkel teared.
It seems 0.5 copper is too much :)
kweld_0.5copperTo0.1nikkel_1834A.jpg
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Last edited by nuxland on Jan 02 2021 1:09pm, edited 1 time in total.
Electric kart 60kw: viewtopic.php?f=34&t=68543
100v 35Ah LiPo battery: viewtopic.php?f=14&t=97763
100v 25Ah LiFePo4 battery: viewtopic.php?f=14&t=85912
Scooter battery: viewtopic.php?f=14&t=108227#p1582703

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Re: kWeld - "Next level" DIY battery spot welder

Post by Hummina Shadeeba » Jan 02 2021 11:07am

flippy wrote:
Jan 02 2021 6:21am
spinningmagnets wrote:
Dec 30 2020 4:49pm
The 0.10mm thick copper may sound thin, but since copper is four times more conductive, with 1/4th the resistance (compared to nickel), the 0.10mm copper is equal in current-carrying ability to 0.40mm thick nickel.
It's also cheaper and more readily available locally than nickel, plus easier to cut.
and it utterly destroys your welding tips.
i think depends on your tips. ive been doing fine after like 1000 welds

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flippy   10 MW

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Re: kWeld - "Next level" DIY battery spot welder

Post by flippy » Jan 02 2021 12:07pm

I think depends on your tips. I've been doing fine after like 1000 welds
That is like <20% of a single battery for me.
Lithium beats liquid dinosaurs.

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Re: kWeld - "Next level" DIY battery spot welder

Post by Hummina Shadeeba » Jan 04 2021 6:36pm

I’m finding the battery amp ability and voltage makes a huge difference


++++ need like 30 joules to weld .1mm copper as said above and not 10 joules as i originally thought. the welds sucked+++
Last edited by Hummina Shadeeba on Jan 21 2021 8:18pm, edited 1 time in total.

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Re: kWeld - "Next level" DIY battery spot welder

Post by AC5ME » Jan 21 2021 6:05pm

I've been having fun welding bits of metal together with my new Kweld but it's not beeping at me as described in the manual. Is this something I can fix?

Thanks!

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Re: kWeld - "Next level" DIY battery spot welder

Post by Hummina Shadeeba » Jan 21 2021 8:19pm

pretty sure the constant beeping is a sign it's working ready to weld. dont know if any way to stop the noise. maybe rip off a chip!

how many welds is appropriate? anyone tested resistance of welds? ive been doing 4 blasts making 8 welds. doing .1mm copper.

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Re: kWeld - "Next level" DIY battery spot welder

Post by AC5ME » Jan 21 2021 8:50pm

It's not making any tones at all, and it would be nice if it did.

Thanks.

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Re: kWeld - "Next level" DIY battery spot welder

Post by Hummina Shadeeba » Jan 22 2021 12:14am

DIY battery dudes I garnered a nugget of what I think is fun fascinating potential with possible pitfalls with potting in polyurethane n I don’t know what elements/chemicals are produced with zapping of copper or nickel but my cure turned bubbly instead of water clear n something has inhibited the cure.


I love sinking it deep in resin. With flesh like silicone molds. The challenges. The obstacles. A father bedside during gestation. A beauty or the danger.

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