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    spot welders

    Contemplating building a bigger pack. Can anyone recommend a good welder or a good DIY project welder?

    Mahalo
    Renn

    #2
    I got this one,SUNKKO 737G 1.5kw spot welder machine led light welding machine for 18650 battery pack off aliexpress. Cost $110. It works but probably could make one that works just as good for cheaper.

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      #3
      Those lower priced machines require you to lift the battery pack up to trigger each spot. Seems like a drag. I would much prefer the pen type, with a foot switch.

      I am working on putting together a DIY spot welder from a 12V motorcycle battery, motorcycle starter relay, momentary button, and solid copper wire for contact ends. I'll post to this thread when it's done, and report results.

      Jose

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        #4
        I finished putting together my 12V DIY welder, and found that I will would have to buy another battery of at least 350CCA to have enough energy for welding .2mm strips. I also found that the welding pen connections heated up really fast, even with my little 150CCA battery. Given the heat issue and cost of buying a battery, I ended up buying one of those little Sunkko 737 110V welders with a foot switch, and my results are mixed. IT doesn't have enough power to weld .2mm strip, but it works really well with .1mm strip. Pliers are needed to remove strips once tacked down, and they will tear at times. I would check welded strips periodically as I was assembling the first part of my pack, and I am confident the welds are all solid. I looked around, and find videos of folks who replace the inner wiring from transformer to welding probes/pen, and they report 100A increases in power. That might be enough to let the Sunkko units weld .2mm strip reliably. I also understand that the 220V version of the welder is more powerful and might be better for welding the thicker strips.

        I am half way through welding my pack, and multi-layering the .1mm strips on my cross battery, and cross parallel group connections should be good to feed the theoretical peak 30A my controller could pull. For home users that don't weld many batteries on a regular basis, I think the Sunkko units are probably the most convenient solution.

        Jose

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          #5
          Update: tightened all bolts, returned to functioning (duh!)
          ---------------------------
          Hi, I got this portable spot welder to make a 10s2p 18650 battery with 3000mAh cells.
          This is my first try at building a battery myself. I hot glued the cells together to hold them in place.
          As you can see, the first 24 or so welds worked fine.
          Then the welder stopped having a welding effect.
          I recharged the battery, it shows 4.15 v across the contacts.
          Anyone have experience with this type of tool, any suggestions?

          Thanks!

          Click image for larger version  Name:	WhatsApp Image 2020-07-27 at 15.02.35.jpeg Views:	0 Size:	170.0 KB ID:	110738Click image for larger version  Name:	WhatsApp Image 2020-07-27 at 15.02.56.jpeg Views:	0 Size:	167.3 KB ID:	110735Click image for larger version  Name:	WhatsApp Image 2020-07-27 at 15.03.13.jpeg Views:	0 Size:	150.8 KB ID:	110736
          Attached Files
          Last edited by amaryeh; 07-27-2020, 05:54 AM.

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            #6
            You want a quality Spot welder for a decent price check out K-Weld. The unit costs less than $200 and you need to get a Lipo battery to power it up $60. I have been making batteries for a couple of years and started off with the Sundko unit and it would weld ok for a single layer of nickel strip. After adding additional layers for my connections they would come loose. Then I went with the Vruzend Caps and mechanically bolted up everything. That was ok but took up a lot of room. We have our batteries inside the main triangle of our bikes and with the Vruzend kits, inside a Luna Bag I could get (8) groups of 14 (52v) 27.6ahr. Now using the K-weld with a nickel 4 row belt for my connections I am getting (11) groups of 14 (52v) 37.95ahr. This thing will weld ou anything you can throw at it. A single strip on a battery I set the power level to 30jl. When adding another single layer I run iy up to 40jl. This thing will go to 250jl!!!!. I typically do (3) pairs of welds per battery connection and I can do one whole side (154) batteries before it drops 1 volt on the Lipo power supply. Check out K-Weld the guy is an Electronics Engineer out of the UK and he will answer any questions you got. And no I'm no affiliated with them in any way.

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              #7
              K-Weld https://www.keenlab.de/index.php/shop/
              and
              DIY Arduino Battery Spot Welder Kit https://malectrics.eu/product/

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                #8
                100% get the K-Weld. I opted to also get the supercap add on and it works amazing.

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                  #9
                  Originally posted by DaHose View Post
                  I finished putting together my 12V DIY welder.

                  I looked around, and find videos of folks who replace the inner wiring from transformer to welding probes/pen, and they report 100A increases in power. That might be enough to let the Sunkko units weld .2mm strip reliably. I also understand that the 220V version of the welder is more powerful and might be better for welding the thicker strips.
                  What was the 12v one? One of those little circuit board ones that range from $20-50? I tend to have 12v batteries around so I would not have to buy one. Also have what is likely better quality wire n stuff around. I wonder if one of those would work for me?

                  Did you find much difference in the Sunkko units that are available in the USA? The all more or less seem to be the same as far as core functions and power just the extra crap that seems to vary. I can so 220v if that helps but most of the listings I see don't say input voltage or frequency. Are some or all of them universal voltage and frequency?

                  So far all I have done is a hack job with a starter solenoid and did some nicad tool batteries but besides another round of those I am kinda interested in building a non conventionally shaped pack for a bike.

                  Comment


                    #10
                    The 12V DIY setups just use a small car, or large motorcycle type battery for more amps. Trigger is just a starter solenoid. Didn't like where it was going, so I went Sunkko. USA units tend to all be 120V. Functions seem the same across both 120/220, it's just that 220V needs less amperage to do the same work. I think that is why they seem better from the git-go. I wanted to be able to plug in and work in places other than my garage, so I decided on the 120V unit. I need to re-wire the inside now that my initial pack is done and see if that helps give it a little more oomph. Input voltage is not the problem, it's the output from the transformer where the Sunkko is weak, so I supposed I might be able to try using a discarded microwave transformer to increase power if better internal wiring doesn't give it enough power for .2mm strip.

                    Jose

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                      #11
                      I was looking at the boards you can buy to use instead of the solenoid which looks like the kind of thing Amaryah was working with. Those would hopefully have better timing and less arching issues.

                      I didn't like the solenoid idea much either. It does work and the magic seems to be getting just the right resistance in the wires and probes, not too much not too little. I thought the wire sizes were a problem and went nuts with some #2 welding cable but that actually made things worse, seems like that system needs a little resistance in there. I had it happen more than one time I think the solenoid must have stuck so it burned through the top of the battery before it burned enough so I could pull it away. Couple more clicks of the pedal and it unstuck. On the nicads I was doing no big deal but I imagine on a lithium pack could make for quite a mess.

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                        #12
                        K-weld users seem really happy, but that is an expensive option that feels more hobbyist battery maker. I just wanted something that works, and doesn't need assembly/batteries. I had enough on my plate with the rest of the build. I'll add to this thread when I get the wires upgraded on my welder and do some testing.

                        Jose

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                          #13
                          I just had another tool battery fail and checked my stash of new nicad cells for them and they still seem to be holding a charge so it may be time to do some more welding experiments. Last time I was using more of a garden tractor sized solenoid that I think was occasionally welding itself shut. Somewhere along the line I apparently bought or found a more HD truck sized one that I would hope would be less prone to the issue. I don't see any point in hooking any sort of timing device like an arduino to a old school slow ass device like a solenoid so if I don't get reasonable results this time I may try one of those $20-50 solid state circuit board dodads. Actually since working on batteries right now would require me to leave the couch and enter my messy frozen garage I may just order one of those boards now so I have it if I ever get the motivation to repair some packs.

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                            #14
                            I just clicked on the link in Amaryah's post above and its a Aliexpress item and for $42 US you get kinda a lot of stuff. It includes a usb rechargeable battery that powers the thing plugs a box case sort of thing as well as some leads. Hmmm..... Even if its doesn't make a great welder there may be some useful bits and pieces there for other experiments and based on the photos and other than some loose screws seems to have worked for Amaryah. I have no doubt that there is better stuff out there but thinking for experiments and tinkering this or something similar may work.

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                              #15
                              Looks like Amazon has that kit for a little less, and you can return it if it doesn't work as expected.

                              https://www.amazon.com/Kecheer-Handh...ag=googhydr-20

                              Jose

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