Likes Likes:  0
Needs Pictures Needs Pictures:  0
Picture(s) thanks Picture(s) thanks:  0
Results 1 to 7 of 7
  1. #1
    Join Date
    Nov 2008
    Location
    North Brisbane. Qld. Australia
    Age
    67
    Posts
    1,075

    Default Lithium Battery Tab Welder

    Anyone have any good cheap Lithium Battery Tab Welder ideas or a links to what they think are simple good ones. Looking at putting tabs on some 18650 cells.
    Nev.

  2. #2
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    4,985

    Default

    Hi Nev, Guys,

    Somewhere on one of my backup discs I have the instructions and construction notes for a microwave oven transformer design. It uses a capacitor bank and a timer, 555 ic, to discharge the capacitors via an SCR.

    You have to remove the high voltage winding and hand wind a secondary to produce about 12 volts, then you select one or more capacitors to discharge into the weld via a two pronged hand held probe made from copper welding rods.

    I don't remember all the details but I did start to modify a transformer to make a spot welder using similar circuitry. I'm sure that I found the details on line, not that I remember where, but I'm sure DuckDuckGo will find something.
    Best Regards:
    Baron J.

  3. #3
    Join Date
    Aug 2019
    Location
    Revesby - Sydney Australia
    Age
    54
    Posts
    477

    Default

    Haven't ever built one, but I liked these primitive "designs":

    https://www.youtube.com/watch?v=1SMUFSiaV-8

    https://www.youtube.com/watch?v=WSXHO7C1vaM

    All low voltage, no transformer rewinding - a large capacitor or three, and a light bulb for safe charging.

  4. #4
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
    Age
    70
    Posts
    2,896

    Default

    I bought and use one of these:
    https://www.youtube.com/watch?v=yyJZFzLnSGE
    I have used it with a car battery and with a RC battery like in the video. Both work perfectly fine. Listen to his warming about using a battery that is too small and the voltage drop to 9V!!!! IMPORTANT.
    I found it had no effect on the charge of the car battery at all, even after an extensive series of welds. So the power used is quite small (lots of amps but for just milliseconds). If you use a small capacity12V battery, its voltage could drop to 9V and the next weld blow the welder up!
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  5. #5
    Join Date
    Aug 2012
    Location
    Greenmount, W.A.
    Age
    67
    Posts
    204

    Default

    Never built one myself, but I gave a friend - who is an electronic / SCADA / computer engineer a microwave oven transformer, and he cut the secondary off, and made two turns (2 vots) of some fibreglass insulate (125c+ insulation) cable about 10mm diameter - that I gave him. The trick is you need the two electrodes very close together - on the new tab - with a bit of a "wrinkle" (on the new tab) between the electrodes so that the current flows across the tab, and the battery's outer case. I think this reduces the temperature rise inside the battery (temperature rise inside battery = explosion!).

    I will go and see him next week.

  6. #6
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    4,985

    Default

    Hi Guys,

    The one thing that I haven't seen mentioned anywhere is that it is important to make sure that the battery contacts are clean ! Any oil, grease or dirt will cause a poor joint. The same applies to the nickel strip.

    A modified microwave oven transformer makes a brilliant spot welder, being able to put several hundred amps into a joint. I bought a five foot 12 mm diameter copper earth rod to make make electrodes with. But you do have to be careful some earth rods are copper coated steel and are no good for this purpose.
    Best Regards:
    Baron J.

  7. #7
    Join Date
    Oct 2021
    Location
    Pakistan
    Age
    29
    Posts
    1

    Default

    With two of those, there might be head room in voltage (29,6V nominal) and capacity (120A for 2 minutes or - in your case - 65A for about 4 minutes).


    Both options have also peak power in excess, being rated at 50C this means that they can generate also up to 260 A (and for a second even twice as much).


    In comparison, regular Li-Ion 18650 batteries are not built for those currents. They are built to get discharged in 30 minutes while 20 is already pretty extreme for them. Densely packed in a container they might easily overheat if stressed with upper position of pipe.

Similar Threads

  1. Gayrad battery cherger
    By kenny_10 in forum ELECTRICALS
    Replies: 24
    Last Post: 29th Sep 2020, 07:55 PM
  2. bulb for battery charger
    By kenny_10 in forum ELECTRICALS
    Replies: 7
    Last Post: 21st Sep 2020, 06:12 PM
  3. Li-Ion Battery to M18 Battery covertor?
    By wm460 in forum METALWORK GENERAL
    Replies: 5
    Last Post: 18th Feb 2019, 06:46 PM
  4. Lithium grease
    By neksmerj in forum METALWORK GENERAL
    Replies: 16
    Last Post: 21st Feb 2014, 02:11 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •